In vivo restoration of T cell functions by human IL-1 beta or its 163-171 nonapeptide in immunodepressed mice

The immunorestorative capacities of human (hu) IL-1 beta or its synthetic fragment 163-171 (VQGEESNDK) were assessed in vivo in mice immunodepressed by aging, sublethal irradiation, or both. Subcutaneous administration of hu rIL-1 beta into immunodepressed animals immediately after carrier (horse red blood cells, HRBC) priming could restore to normal levels Th cell activity. This was measured as the ability of spleen cells from HRBC-primed mice to induce a hapten-specific antibody response in spleen cells from nonimmune mice in vitro stimulated with the hapten-carrier conjugate TNP-HRBC. In parallel, the ability of spleen cells from hu rIL-1 beta-treated immunodepressed animals to produce T cell growth factor activity upon in vitro mitogen stimulation was also increased significantly as compared to that of untreated mice and approached that of immunocompetent controls. The immunorestorative activity of hu rIL-1 beta on Th cell activity and T cell growth factor production could be mimicked by the synthetic nonapeptide 163-171 which, at the doses used, produced in most instances even greater effects than the whole protein. Although the optimal immunorestorative doses of the 163-171 peptide were several orders of magnitude higher than those of hu rIL-1 beta, the complete lack of IL-1-like inflammatory and toxic effects suggests that the synthetic hu IL-1 beta fragment may be successfully used as immunomodulating agent in the therapy of T cell immunodeficiencies.     

Postsurgical adjuvant chemoimmunotherapy with recombinant interleukin-2 and 1,3-bis-(2-chloroethyl)-1-nitrosurea on spontaneous metastases of a non-immunogenic murine tumour

Summary The efficacy of the association of recombinant interleukin-2 (rIL-2) with chemotherapy has been investigated on an experimental model representative of clinical tumours, i.e. on post-surgical spontaneous metastases of a non-immunogenic tumour. We used the M5076 ovarian reticulum cell sarcoma, which metastatizes to the liver after intra-footpad implantation. Such a tumour appeared to be non-immunogenic by a variety of commonly used in vivo assays. Four clinically widely employed drugs, i.e. doxorubicin,cis-diamminedichloroplatinum II, cyclophosphamide and 1,3-bis-(2-chloroethyl)-1-nitrosurea (BCNU), were tested and BCNU proved to be the most effective one when administered as single injection at the maximum tolerated dose (33 mg/kg i.p.) 1 day after tumour excision. When moderate doses of rIL-2 (6 × 10⁵ IU in three injections per day for 5 days) were administered at three different intervals after BCNU, namely before the nadir of white blood cells (1 day after BCNU), at the nadir (3 days after BCNU) or at recovery (6 days after BCNU), no increase in BCNU antitumour activity was observed. The same results were obtained by administering rIL-2 for 5 days before BCNU. Higher doses of rIL-2 (1.2 × 10⁶ IU in three injections per day for 5 days), which were always well tolerated in sham-excised non-tumour-bearing mice, proved lethal in two out of four experiments in tumour-bearing animals. In the two experiments in which no lethality was observed, the administration of high doses of rIL-2 1 or 6 days after BCNU significantly increased the antitumour activity of BCNU alone. rIL-2 alone was not active even when administered at high doses. These results indicate that high but not moderate doses of rIL-2 may increase the activity of BCNU against a non-immunogenic tumour. Moreover, they suggest that rIL-2 tolerability is reduced in tumour-bearing mice.     

Enhanced oral tolerance in transgenic mice with hepatocyte secretion of IL-10

Several cytokines derived from Th3 and Tr1 cells, including IL-10, are believed to regulate oral tolerance, but direct evidence is lacking. We have explored the potential role of IL-10 by generating transgenic (TG) mice with sustained hepatocyte-specific expression of rat IL-10. TG mice expressed rat IL-10 downstream of a transthyretin promoter, which led to serum levels that were increased 10- to 100-fold compared with normal animals. Animals were orally administered 1 mg of whole OVA for 5 consecutive days, with control animals receiving PBS. There were six animal groups: Either OVA or PBS were fed orally to rat IL-10 TG mice, non-TG wild-type mice without IL-10 administration, and non-TG wild-type mice administered rat IL-10 systemically. On day 8, all mice were immunized with two injections of OVA, and then analyzed on day 18. T cell proliferation responses were reduced by 65.8 +/- 14.3% after feeding of OVA in rIL-10 TG animals, compared with 39.4 +/- 15.6% in the non-TG mice (p = 0.02). Anti-OVA titers were expressed as fold increase over naive non-TG mice. After feeding, titers decreased by approximately 33% (from 3- to 2-fold) in TG animals and, to a lesser extent, in non-TG animals. IFN-gamma secretion by cultured popliteal lymphocytes decreased in TG animals by 83% after feeding and by 69% in non-TG animals. IL-4 secretion increased 4-fold in TG-fed mice, but did not significantly change in non-TG OVA-fed animals. In contrast to hepatic TG expression of rIL-10, systemic administration of rIL-10 had only a modest effect on tolerance. IL-10, when transgenically expressed in the liver enhances mucosal tolerance to an oral Ag.     

Augmentation of natural killer activity, induction of IFN and development tumor immunity during the successful treatment of established murine renal cancer using flavone acetic acid and IL-2

The investigational drug flavone acetic acid (FAA) has been previously shown to systemically augment NK activity in vivo in normal mice within 24 h of i.p. or i.v. administration. The current study investigates the ability of FAA, and/or rIL-2, to augment NK activity and antitumor responses in mice bearing murine renal cancer (Renca). The results demonstrate that FAA potently augments NK activity in the blood, spleen, and liver of Renca-bearing mice and that the administration of rIL-2 in addition to FAA results in a further augmentation of NK activity over that observed with FAA alone. Renca-bearing mice treated with FAA (200 to 250 mg/kg) plus rIL-2 exhibited a significantly increased incidence of long term survivors (59%) over that observed following treatment with FAA (0%) or rIL-2 (5%) alone. Therapeutic synergy between FAA and rIL-2 was observed against primary tumors, minimal residual disease, and experimental-induced pulmonary metastases. Mice cured of Renca by FAA plus rIL-2 treatment were largely resistant to rechallenge with Renca suggesting a role for T lymphocytes. The augmentation of NK activity and the therapeutic effects of FAA coincided with the rapid induction of high titers of serum IFN of the alpha/beta type within 4 h of FAA administration. Subsequent studies demonstrated that the contribution of FAA could be partially replaced by the administration of several doses of human rIFN-alpha A/D Bg1 before the initiation of rIL-2 administration. The observed synergistic antitumor effects of FAA plus rIL-2 coincided with the augmentation of NK activity, induction of IFN-alpha/beta, and induction of long lasting tumor immunity. Overall, these results suggest that this approach may obviate the need for adoptive immunotherapy in association with rIL-2 administration for at least some tumor types.     

Immunotherapy with intralesional and systemic interleukin-2 of patients with non-small-cell lung cancer

Eight patients affected by non-small-cell lung cancer were treated with intralesional and systemic recombinant IL-2(rIL-2) injection with the aim of activating both tumour-infiltrating lymphocytes and circulating cytotoxic or killer cells. The schedule of treatment was as follows: a daily fine-needle transparietal intralesional rIL-2 injection (1×10⁵ Cetus units) from day 1 to day 5 and systemic rIL-2 infusion (1×10⁵ Cetus units kg^–1 day^–1) from day 6 to day 10. One to four cycles of treatment were received by each patient. Clinical and immunological evaluations were performed (a) before treatment, (b) following the intralesional rIL-2 administration, (c) 1 h after the beginning of rIL-2 infusion and (d) at the end of the systemic rIL-2 infusion. No complete remission was achieved, two patients showed a partial remission, three resulted in stable disease and three patients progressed. Natural killer and lymphokine-activated killer cell activity dramatically decreased 1 h after the beginning of rIL-2 infusion and increased at the end of treatment. A progressive increase of circulating CD8⁺ and HLA class II⁺ T cells as well as of CD8⁺ T cell clones, most of which displayed NK activity, was recorded following rIL-2 infusion. Present data indicate that (a) the local administration of rIL-2 coupled with systemic rIL-2 infusion may be suggested as an alternative approach for the immunotherapy of lung cancer, (b) rIL-2 induces different immunological modifications according to the route and the time of its administration and (c) rIL-2 administration increases the amount of circulating immune cells with potential antitumour activity.     

Enhanced cell-mediated protection against fatal Escherichia coli septicemia induced by treatment with recombinant IL-2

Administration of rIL-2 to BALB/c mice induces a rapid, cell-mediated response that is sufficient to protect mice from a lethal i.p. dose of Escherichia coli. Mice were protected from septic death if IL-2 was administered i.p. within 1 h after the bacterial challenge. Optimal protection was provided by treating the lethally challenged mice with rIL-2 at 1 and 5 h or 1, 5, and 10 h after the bacterial challenge and was dose-dependent (greater than or equal to 5.0 x 10(5) U/kg). Furthermore, treatment of mice with anti-IL-2R antibody abolished the protective effect induced by rIL-2 administration. These data suggest that the rIL-2-induced protection against septic death in mice is mediated by a cell type expressing a functional IL-2R. One potentially important therapeutic application of rIL-2 may be to modulate the course of sepsis once the host has been exposed to potentially lethal microbial pathogens.     

Antigenic challenge of immunized mice induces endogeneous production of IL-3 that increases histamine synthesis in hematopoietic organs

Antigenic challenge of Nippostrongylus brasiliensis-infected mice induces a striking increase in histidine decarboxylase (HDC) activity in both spleen and bone marrow cells. This enhancement takes place within 1 h after injection, with a maximum at 4 h and a return to pretreatment values 20 h later. It is associated with the appearance of IL-3 in the sera of these mice. In addition, the intracellular histamine content in both hematopoietic organs is concomitantly increased. A similar injection of worm Ag into normal mice has no significant effect. Comparable enhancement of HDC activity and intracellular histamine content with almost identical kinetics is promoted by i.v. injection of rIL-3 into normal mice. Moreover, HDC levels in infected mice are increased to the same extent in response to either specific antigen or rIL-3 injection. Taken together these results support the conclusion that antigenic challenge of immunized mice induces endogeneous IL-3 which, in turn, promotes a rapid increase in histamine synthesis in hematopoietic organs.     

Effects of murine recombinant interleukin 1 alpha on the host response to bacterial infection

The effects of exogenously administered rIL-1 alpha on elimination of viable listeriae from the liver and spleen during the course of a primary Listeria monocytogenes infection was studied. Similar numbers of L. monocytogenes were recovered from rIL-1 alpha-treated and control mice at up to 24 h after infection; however, by 48 h after infection more than 1 log10 fewer viable L. monocytogenes were recovered from the spleens of rIL-1 alpha-treated mice than from Listeria-infected controls. The difference in bacterial burden between IL-1 alpha-treated and control mice increased with time; by 7 days after infection viable L. monocytogenes had been eliminated from most rIL-1 alpha-treated mice, whereas control mice still harbored 10(4) to 10(5) L. monocytogenes per spleen and liver. Histopathologic examination confirmed that rIL-1 alpha-treated mice suffered considerably less damage to the spleen, liver, lung, and brain than did control mice. To determine whether rIL-1 alpha-mediated protection indirectly by augmenting the release of other cytokines, we determined serum levels of colony-stimulating activity and IFN activity in rIL-1 alpha-treated and control Listeria-infected mice. Treatment with rIL-alpha elicited an early burst of serum colony-stimulating activity as compared with sera from Listeria-infected control mice. These data suggest that exogenous administration of rIL-1 initiates release of colony-stimulating activity, and perhaps other cytokines, that accelerate the protective response of the infected host. Prophylactic augmentation of antimicrobial resistance by administration of rIL-1 alpha may be worthy of further evaluation.     

Effects of intravenous IL-8 administration in nonhuman primates.

IL-8, a cytokine known for its potent and specific neutrophil activation and chemoattractant properties, has been recently detected in the circulation during septic shock, endotoxemia, and after IL-1 alpha administration. Because of its observed in vitro actions, it has been hypothesized that IL-8 may contribute to the dynamics of circulating granulocytes and to the pathologic sequelae seen in sepsis. Here, human rIL-8 is administered to healthy nonhuman primates as a single i.v. injection or as a continuous 8-h i.v. infusion. We demonstrate that both methods of i.v. administration result in a rapid but transient, severe granulocytopenia, followed by a granulocytosis that persists as long as IL-8 levels are detectable in the circulation. There were no hemodynamic changes after IL-8 administration, and animals remained clinically stable during the 24-h observation period. No detectable circulating TNF-alpha, IL-1 beta, or IL-6 response was induced by either IL-8 administration regimen. Histopathologic examination revealed mild to moderate neutrophilic margination in lung, liver, and spleen, of greater severity in baboons receiving the 8-h infusion. There was no associated neutrophilic infiltration or tissue injury. Thus, IL-8 modulates circulating granulocyte dynamics and likely directs their actions, but when administered i.v. to healthy animals, either as a bolus dose or as a continuous infusion for up to 8 h, does not induce the hemodynamic and metabolic aberrations or the acute organ damage seen during sepsis.     

Administration of recombinant IL-4 to humans regulates gene expression, phenotype, and function in circulating monocytes.

As a multifunctional cytokine that can augment certain T cell responses, IL-4 is being evaluated currently as a possible therapeutic agent in the treatment of cancer patients. In this report, PBMC were isolated from such patients before and after IL-4 therapy and were analyzed for phenotypic and functional alterations. Differential blood counts showed that the relative percentages of lymphocytes and, to a lesser degree, monocytes decreased after treatment with IL-4. However, when phenotypically analyzed by FACS, monocyte numbers generally increased, whereas there was a decrease in lymphocyte numbers. Monocytes taken from patients before therapy and cultured with and without LPS exhibited normal patterns of monokine-specific (IL-1 beta and TNF-alpha) mRNA expression, as well as secretion of peptide. The addition of rIL-4 to these cultures, however, resulted in the down-regulation of both gene expression and peptide release. Although monocytes taken from post-therapy patients also displayed normal patterns of monokine gene expression and cytokine release after stimulation with LPS, they were no longer inhibited by the addition of exogenous rIL-4 in vitro. These data suggest that monocytes become refractory to the inhibitory effects of IL-4 after in vivo exposure to this cytokine. However, when these monocytes were examined for expression of CD14, CD32, and CD64, exogenous IL-4 was observed to decrease markedly the appearance of these markers, regardless of whether the cells were obtained before or after therapy. Furthermore, monocytes from post-therapy patients exhibited reduced production of PGE2 and superoxide anion, compared with cells obtained before therapy. This effect persisted in culture independent of the further addition of exogenous IL-4. These data suggest a dichotomy between the IL-4-dependent mechanisms that regulate monokine production and those that regulate certain other monocyte functions. The exact mechanisms that govern these two pathways are not known. These results have important clinical implications for the use of IL-4 as an immunotherapeutic agent, as well as providing insight into the physiologic role of IL-4.     

Statins accelerate the onset of collagen type II-induced arthritis in mice

Introduction

Statins (hydroxymethylglutaryl coenzyme A reductase inhibitors) are effective in reducing the risk of cardiovascular morbidity and mortality in patients with hyperlipidemia, hypertension, or type II diabetes. Next to their cholesterol-lowering activity, statins have immunomodulatory properties. Based on these properties, we hypothesized that statin use may eventually lead to dysregulation of immune responses, possibly resulting in autoimmunity. We have recently shown in an observational study that statin use was associated with an increased risk of developing rheumatoid arthritis. Our objective was to investigate whether a causal relationship could be established for this finding.

Methods

The mouse collagen type II (CII)-induced arthritis (CIA) model was used, with immunization, challenge, and euthanasia at days 0, 21, and 42, respectively. Statins were given orally before (day -28 until day 21) or after (day 21 until day 42) CIA induction. Atorvastatin (0.2 mg/day) or pravastatin (0.8 mg/day) was administered. Arthritis was recorded three times a week. Serum anti-CII autoantibodies and cytokines in supernatants from Concanavalin-A-stimulated lymph node cells and CII-stimulated spleen cells were measured.

Results

Statin administration accelerated arthritis onset and resulted in 100% arthritic animals, whereas only seven out of 12 nonstatin control animals developed arthritis. Atorvastatin administration after CIA induction resulted in earlier onset than atorvastatin administration before induction, or than pravastatin administration before or after induction. The arthritic score of animals given pravastatin before CIA induction was similar to that of the nonstatin controls, whereas the other groups that received statins showed higher arthritic scores. Atorvastatin administration, especially before CIA induction, increased anti-CII autoantibody production. IL-2 and IL-17 production by lymph node and spleen cells was higher in CIA animals than in PBS controls, but was not affected by statin administration. While IFNγ production was not affected by CIA induction, atorvastatin administration before CIA induction increased the production of this cytokine.

Conclusion

These data support previous results from our observational studies, indicating a role for statins in the induction of autoimmunity.     

Adoptive immunotherapy of a mouse colon carcinoma with recombinant interleukin-2 alone or combined with lymphokine-activated killer cells or tumor-immune lymphocytes

Summary We have used a BALB/c colonic adenocarcinoma (C-26) to evaluate the therapeutic potential of recombinant interleukin-2 (rIL-2) at high and low dosages in combination with or without lymphokine-activated killers (LAK) or tumor-specific, immune lymphocytes in either an adjuvant spontaneous or an artificial metastasis system. Most (80%) of the mice that underwent s.c. C-26 tumor excision were shown to die of spontaneous metastasis with lung involvement by 1–4 months after excision. Postsurgical systemic treatment with low-dose rIL-2 (3 × 10⁴ U/day, i.p.) increased the survival rate to 31% as compared to 21% (not significant) in excised controls while administration of high-dose rIL-2 (8 × 10⁴ U/day) led to 53% survival (P <0.01). Both LAK cells and C-26-tumor-immune lymphocytes given during rIL-2 treatment significantly increased the effects of rIL-2 at the low but not at the high-dose, with tumor-immune effectors resulting in the highest percentage (63%) of cures. When mice bearing 3-day artificial lung metastases of C-26 cells were treated with low- or high-dose rIL-2, in combination with or without LAK or tumor-immune lymphocytes, a highly significant reduction or abrogation of the number of lung foci was observed with all treatments, including those involving or tumor-immune lymphocytes alone. Assessment of survival benefit in these mice, however, showed survival prolongation, with 20% cures achieved by low-dose rIL-2 alone and up to 65% cures by LAK in combination with low-dose rIL-2. In this system of artificial metastasis high-dose rIL-2 alone increased the survival time but failed to cure the animals, and the addition of LAK was ineffective whereas that of tumor-immune lymphocytes led to 80% cure. These results suggest that tumorimmune lymphocytes are more effective than LAK when combined with rIL-2 and that caution is necessary in extrapolating findings obtained in artificial metastasis models.     

Generation of tumor-specific cytotoxic T lymphocytesin vivo by combined treatment with inactivated tumor cells and recombinant interleukin-2

In order to search for a new therapy that would maximize the effect of interleukin-2 (IL-2) in evoking antitumor immunity in vivo, the therapeutic effect of a combination of mitomycin-C(MMC)-treated tumor cells and recombinant IL-2 was examined for its induction of antitumor activity against established melanoma metastasis. In C57BL/6 mice intravenously (i. v.) injected with B16 melanoma cells on day 0, the combined treatment with an intraperitoneal (i. p.) injection of MMC-treated melanoma cells on day 6 and 2500 U rIL-2 (twice daily) on days 7 and 8 markedly reduced the number of pulmonary metastases. This antitumor activity was more effective than that in untreated controls and mice that were injected with MMC-treated melanoma cells alone or rIL-2 alone. When the i. p. injection of MMC-treated tumor cells was replaced by other syngeneic tumor cells, antitumor activity against metastatic melanoma was not induced. The antitumor activity induced by this treatment increased in parallel with an increase in the dose of rIL-2 injected. In contrast, an i. p. injection of soluble tumor-specific antigens alone could induce only a marginal level of antitumor activity, and this activity was not augmented by subsequent i. p. injections of rIL-2. In vivo treatment with anti-CD8 monoclonal antibody (mAb), but not with anti-CD4 mAb or anti-asialo-GM1 antibody, abrogated the antitumor activity induced by this combined therapy. This suggests that the antitumor effect was dependent on CD8⁺ T cells. Lung-infiltrating lymphocytes from mice that had been i. v. injected with melanoma cells 11 days before and were treated with this combined therapy, showed melanoma-specific cytolytic activity. This combined therapy also showed significant antitumor activity against subcutaneously inoculated melanoma cells. These results demonstrate that the combined therapy of an i. p. injection of MMC-treated tumor cells and subsequent and consecutive i. p. administration of rIL-2 increases antitumor activity against established metastatic melanoma by generating tumor-specific CD8⁺ CTL in vivo.     

Antibacterial resistance induced by recombinant interleukin 1 in myelosuppressed mice: effect of treatment schedule and correlation with colony-stimulating activity in the bloodstream

We have investigated the effects of interleukin 1 (IL-1) administration on the ability of neutropenic mice to resist Pseudomonas aeruginosa challenge in vivo. Cyclophosphamide-treated mice received human rIL-1 beta at 7.0, 0.7, or 00.7 micrograms/kg, according to different regimens, to be challenged with a lethal ip inoculum of pseudomonas cells 5 days after myelosuppression. The repeated exposure of the neutropenic mice to an overall cytokine dosage of 7.0 or 0.7 micrograms/kg during the 4 days after myelosuppression was found to optimally restore the animals' antibacterial resistance. However, when administered as a single injection 24 hr before challenge, the same dosages of IL-1 had lower or no effect in enhancing survival, primarily leading only to a reduction in the amount of antipseudomonal chemotherapy required for cure. The regimen of IL-1 administration conferring optimal protection also resulted in a decrease in the number of pseudomonas cells recovered from the peritoneal cavity of infected mice. This regimen accelerated hematopoietic recovery in cyclophosphamide-treated mice. Assay of serum colony-stimulating activity (CSA) revealed that (a) cyclophosphamide treatment alone significantly increased the level of circulating CSA, (b) administration of a single dose of IL-1 to neutropenic mice induced an early, further increase in serum CSA, followed by depression, (c) a biphasic pattern of CSA response was also evident in mice repeatedly treated with IL-1. These results suggest that regulation of hematopoiesis may have an important role in the induction of antibacterial resistance in myelosuppressed hosts repeatedly treated with low dosages of IL-1.     

Involvement of the liver, but not of IL-6, in IL-1-induced desensitization to the lethal effects of tumor necrosis factor.

C57BL/cnb mice were found to be protected against a lethal combination of recombinant murine (m) TNF and GalN by pretreatment with several cytokines. At certain doses, rmTNF and human (h) TNF protected completely. The clearest protection was induced by rIL-1: all four rIL-1 species (both m and h, as well as alpha and beta) protected when given 12 h before the challenge. LPS and rmIFN-gamma protected weakly, whereas rmIL-6 and rhIL-6 did not protect at all. Also adrenocorticotropic hormone, dexamethasone, or dexamethasone in combination with rhIL-6 could not protect. A single IL-1 injection also completely protected mice against a lethal dose of mTNF in the absence of GalN sensitization. The desensitization by IL-1 cannot be explained by a faster clearance of the challenge TNF. In addition, we demonstrate that the IL-1-induced desensitization was only observed when a functioning liver was present, that IL-1-pretreated animals did not show decreased numbers of hepatocyte TNF receptors, and that the amount of TNF-induced IL-6 was not reduced.     

Interleukin-1 alpha stimulates prostaglandin biosynthesis in serum-activated mesangial cells by induction of a non-pancreatic (type II) phospholipase A2

Enhanced prostaglandin (PG) biosynthesis is a hallmark of inflammation, and interleukin-1 (IL), a proinflammatory cytokine, is a potent stimulus of PG production. We investigated the mechanisms of IL-1 alpha-enhanced PG synthesis in serum-stimulated mesangial cells. The rIL-1-stimulated increase in PGE2 synthesis was dose- and time-dependent and inhibited by both cycloheximide and actinomycin D. Phospholipase (PL) activity was increased 5- to 10-fold in acid extracts of rIL-1-treated cells as measured by arachidonate release from exogenous [14C]arachidonyl-phosphatidyl-ethanolamine. This induced phospholipase activity was Ca(2+)-dependent and inhibited by the PLA2 inhibitors, aristocholic acid, 7,7-dimethyl-5,8-eicosadienoic acid, and p-bromophenacylbromide, but not by the 1,2-diacylglycerol lipase inhibitor RHC 80267. The rIL-1-stimulated PLA2 had an alkaline pH optimum, and phosphatidylethanolamine was preferred over phosphatidylcholine as substrate. The PLA2 activity increased by rIL-1 was inhibited in cells coincubated with cycloheximide and was measurable after 6 h. A sensitive and specific solution hybridization assay demonstrated a coordinate time-dependent induction of non-pancreatic PLA2 mRNA expression which was increased at least 6-fold by 24 h. In whole cells, IL-1 had no effect on basal [3H]arachidonic acid release but vasopressin (1 microM)-stimulated release was potentiated 2- to 3-fold, suggesting that IL-1 may prime cells for increased PG synthesis via increased PLA2 activity. Thus IL-1 directly stimulates, as well as primes cells for, enhanced PG synthesis, in part, by increasing PLA2 activity through new synthesis of a non-pancreatic (Type II) PLA2.     

Differential antitumor effects of administration of recombinant IL-18 or recombinant IL-12 are mediated primarily by Fas-Fas ligand- and perforin-induced tumor apoptosis, respectively.

Systemic administration of rIL-18 protein to mice significantly suppresses the growth of murine tumor cell lines. The antitumor effect of IL-18 appears to be primarily mediated by asialo GM1+ cells. Since IL-18 enhances Fas ligand (FasL) expression on NK cell lines, the IL-18 antitumor effects could be mediated by FasL-induced cross-linking of Fas and subsequent tumor apoptosis. To address this question, rIL-18 or rIL-12 was administered to animals bearing the CL8-1 melanoma inoculated intradermally into wild type (wt), lymphoproliferation gene (lpr) (Fas deficient), or generalized lymphoproliferative disease gene (gld) (FasL deficient) mice. Although rIL-12 treatment retained significant antitumor effects in gld and lpr mice, those of rIL-18 administration were completely abrogated in gld but not lpr or wt mice. In vitro cytotoxicity was significantly enhanced against NK-sensitive YAC-1 cells and CL8-1 cells by rIL-18 administration to wt mice, but not to gld mice. Furthermore, rIL-18 administration augmented the cytotoxicity of liver lymphocytes harvested from perforin-deficient mice, whereas rIL-12 administration did not. Consistent with the role of this pathway, rIL-18 administration also up-regulates the expression of FasL mRNA in splenocytes. Lysis of CL8-1 cells induced by anti-Fas agonistic Ab was enhanced about 1.4-fold by IFN-gamma, a cytokine that is induced by IL-18 in vitro and in vivo. We conclude that the antitumor effect of IL-18 is exerted predominantly through a Fas-dependent pathway. The perforin pathway, however, appears to be the predominant cytolytic pathway mediating IL-12 antitumor effects.     

The effect of three years of TNF alpha blocking therapy on markers of bone turnover and their predictive value for treatment discontinuation in patients with ankylosing spondylitis: a prospective longitudinal observational cohort study

Introduction

Statins (hydroxymethylglutaryl coenzyme A reductase inhibitors) are effective in reducing the risk of cardiovascular morbidity and mortality in patients with hyperlipidemia, hypertension, or type II diabetes. Next to their cholesterol-lowering activity, statins have immunomodulatory properties. Based on these properties, we hypothesized that statin use may eventually lead to dysregulation of immune responses, possibly resulting in autoimmunity. We have recently shown in an observational study that statin use was associated with an increased risk of developing rheumatoid arthritis. Our objective was to investigate whether a causal relationship could be established for this finding.

Methods

The mouse collagen type II (CII)-induced arthritis (CIA) model was used, with immunization, challenge, and euthanasia at days 0, 21, and 42, respectively. Statins were given orally before (day -28 until day 21) or after (day 21 until day 42) CIA induction. Atorvastatin (0.2 mg/day) or pravastatin (0.8 mg/day) was administered. Arthritis was recorded three times a week. Serum anti-CII autoantibodies and cytokines in supernatants from Concanavalin-A-stimulated lymph node cells and CII-stimulated spleen cells were measured.

Results

Statin administration accelerated arthritis onset and resulted in 100% arthritic animals, whereas only seven out of 12 nonstatin control animals developed arthritis. Atorvastatin administration after CIA induction resulted in earlier onset than atorvastatin administration before induction, or than pravastatin administration before or after induction. The arthritic score of animals given pravastatin before CIA induction was similar to that of the nonstatin controls, whereas the other groups that received statins showed higher arthritic scores. Atorvastatin administration, especially before CIA induction, increased anti-CII autoantibody production. IL-2 and IL-17 production by lymph node and spleen cells was higher in CIA animals than in PBS controls, but was not affected by statin administration. While IFN?? production was not affected by CIA induction, atorvastatin administration before CIA induction increased the production of this cytokine.

Conclusion

These data support previous results from our observational studies, indicating a role for statins in the induction of autoimmunity.     

Comparison between crude Interleukin-2 and recombinant Interleukin-2 in maintaining killing activity of cultured lymphocytes

Peripheral blood lymphocytes, regional lymph node lymphocytes or malignant effusion lymphocytes from cancer patients were incubated with crude IL-2 (cIL-2) for 13 days. These effectors, which frequently expressed IL-2 receptor (IL-2R), proliferated well and possessed augmented killing activity against fresh autologous tumor cells and K562. However, when recombinant IL-2 (rIL-2) was added for the last 4 days of culture instead of cIL-2, IL-2R expression and killing activity against fresh autologous tumor cells decreased significantly (P<0.05). Phenotypic analysis indicated that cIL-2 significantly promoted the expansion of the cytotoxic population (CD8⁺ .11b^–)(P<0.05). The decreases in killing activity and IL-2R expression were restored by 0.004% PHA plus rIL-2, but not in the presence of rIFN-, rIL-1, rIL-l, rIL-4 or rIL-6. PHA-free cIL-2 maintained killing activity, but not IL-2R expression.We conclude that some factors in cIL-2 and a low dose of PHA-P are necessary for the maintenance of killing activity and IL-2R expression of cultured lymphocytes in the late phase of culture.