The lack of generalized immunosuppression in C57BL/6 mice during progressive growth of syngenic T lymphoma EL-4 and Lewis lung carcinoma 3LL

The immune competence of C57Bl/6 mice implanted with EL-4 lymphoma of Lewis Lung carcinoma 3LL was investigated during 3 weeks after implantation. Splenic lymphocyte responses to mitogens (Con A, PHA, LPS, PWM) cytotoxic T lymphocytes (CTL) and interleukin-2 (IL-2) production were assessed. A dramatic reduction in mitogenic responses to Con A and PHA was observed during tumour progression. LPS and PWM responses were less depressed. Con A-induced IL-2 production correlated with Con A and PHA responses. Allospecific CTL response to mastocytoma P 815 was not decreased in syngeneic tumour-bearing mice.     

The inhibitory effect of human syncytiotrophoblast plasma membrane vesicles on in vitro lymphocyte proliferation is associated with reduced interleukin 2 receptor expression

The mechanisms by which vesicles of syncytiotrophoblast plasma membranes (STPM) prepared from full-term human placentas inhibit lymphocyte proliferation have been investigated. In the presence of STPM, IL-2 secretion and the expression of protein P55 (IL-2R P55) from its receptor were examined in two models of PBMC proliferation: induced by PHA in 3-day-old cultures, and induced by IL-2 in 6-day-old cultures. In the case of PHA stimulation, STPM strongly inhibited IL-2 (but not IL-1) secretion and IL-2R P55 expression at a concentration where lymphocyte proliferation was also blocked. In these conditions, the addition of excess recombinant IL-2 (rIL-2) only partially restored proliferation and IL-2R P55 expression. In addition, STPM inhibited proliferation and IL-2R P55 expression when resting PBMC were stimulated by a high concentration of rIL-2. These results suggest that STPM inhibit lymphocyte proliferation by affecting one or several events occurring in the synthesis and/or expression of IL-2R P55 by a mechanism which is at least partially independent of its inhibitory effect on IL-2 secretion. The significance of these results is discussed in the context of the survival of the fetal allograft.     

Study of the possibility to abolish the action of immunosuppressive factors of tumor cells]

We investigated the efficacy of IL-2, LPS, MDP, TRA, ionomycin and contrykal on proliferation of lymphocytes treated by tumor cell immunosuppressive factors (ISF). IL-2, LPS and/or MDP did not abolish the influence of P815 and B16 ISF on Con A or alloantigen-induced lymphocyte proliferation. TPA and in less extent ionomycin and combination of the above preparations totally abrogated the suppression of Con A-induced lymphocyte proliferation. In inverted experiments Con A abrogated ISF-mediated suppression of lymphocyte proliferation induced by TPA plus ionomycin.     

电剌大鼠的血清中淋巴细胞转化抑制因子的作用机制分析

Previous reports showed that EA stimulation (3V, 2Hz, 30 min/d, 5 d) induced the production of one or more lymphocyte proliferation-inhibitory factor(s) in the rat serum. In this paper, the mechanisms of the action for the inhibitory factor(s) to suppress lymphocyte proliferation were studied. (1) the lymphocytes from different immune organs of the mice were prepared and cultured with the rat serum stimulated by EA. The results show that the serum not only inhibited the mouse lymph node T cell proliferation induced by Con A, but also inhibited the mouse thymocyte and spleen T cell proliferation induced by Con A. When B cells were stimulated by LPS, the proliferative effect can also be inhibited significantly by the rat serum stimulated by EA. This implies that the effect of the lymphocyte proliferation-inhibitory factor(s) has no specificity. (2) Incubation of the mouse lymph node cell with serum for one hour is enough to cause an inhibitory effect on Con A stimulated lymphocyte proliferation. However, no inhibitory effect was observed if the mouse lymph node cells were incubated with Con A for 15 min or 30 min before the addition of rat serum. The results demonstrate that the lymphocyte proliferation-inhibitory factor(s) act on the early events of T lymphocyte activation induced by Con A. (3) Protein kinase C (PKC) is a key link in the activation of T and B lymphocyte proliferation by Con A and LPS respectively. So it would be interesting to learn whether the inhibitory effect of the lymphocyte proliferation-inhibitory factor(s) is caused by the inhibition of PKC activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interleukin 1 secretion is not required for human macrophage support of T-cell proliferation

Interleukin 1 (IL-1) is a soluble factor secreted by stimulated monocytes (Mo) and animal macrophages (Mx). We have previously demonstrated that human Mo cultured in vitro for 1-6 days transform to Mx, and retain their ability to support concanavalin A (Con A)-driven T-cell proliferation. We have also shown that, paradoxically, these Mx do not secrete IL-1, when stimulated by endotoxin (LPS). In this study we examined two alternative hypotheses: T cells plus mitogen induce Mx IL-1 production, and human Mx deliver a second signal to T cells via a non-IL-1 mechanism. IL-1 was assayed in a mouse CD-1 thymocyte system without concanavalin A. Mo/Mx were cultured with T cells at low (2 X 10(4)/200 microliters) or high (1 X 10(5)/200 microliters) concentrations for 2 or 4 days, in the presence of Con A. Six hours prior to quantitation of proliferation, 50 microliters of supernatant was removed and assayed for IL-1. As expected both Mo and Mx enhanced T-cell proliferation eight- to tenfold. Mo secreted large amounts of IL-1; there was no demonstrable IL-1 activity present in supernatants from cultures containing either T cells and Mx, or Mx alone. Similar results were obtained by preincubating the cells (Mo, Mx, and T cells) with Con A for 12 hr and removing Con A prior to a 36-hr coculture. We examined the possibility that a small amount of IL-1 may be able to support Con A-stimulated T-cell proliferation and yet may not induce thymocyte proliferation. The highest dilutions of Mo supernatant (1:125) which supported T-cell proliferation also caused a fivefold increase in thymocyte proliferation. Supernatants from Mx failed to stimulate thymocyte proliferation or support Con A-driven T-cell proliferation. However, Mo and Mx lysates contain Il-1 activity. We conclude that human Mx support Con A-induced T-cell proliferation in the absence of IL-1 secretion. Mx may support T-cell proliferation by cell-bound IL-1 or by a non-IL-1 mechanism.     

Regulation of T cell proliferation by IL-7

The regulation of murine T cell proliferation by IL-7 was investigated. Highly purified resting splenic T cells were induced to proliferate in a short term assay by IL-7 in the presence of the comitogen, Con A. The proliferation of these resting T cells showed both IL-2-dependent and -independent components as determined by the susceptibility of the response to the blocking effects of anti-IL-2 mAb. Furthermore, IL-7 was found to augment the Con A-induced production of IL-2 and expression of IL-2R by resting splenic T cells. In contrast, Con A blasts and long term, Ag-dependent cloned T cells proliferated in response to IL-7 independently of any involvement of IL-2. Finally, differences were observed between IL-7 and IL-6 with regard to the regulation of T cell growth and activation. As with IL-7, IL-6 stimulated resting splenic T cells to proliferate in the presence of comitogen. However, in contrast to IL-7, IL-6 failed to stimulate the proliferation of Con A blasts or T cell clones and did not augment the Con A-induced expression of IL-2R on resting T cells.     

TH1 and TH2 cytokine inhibition by 3,5-bis(trifluoromethyl)pyrazoles,a novel class of immunomodulators

In order to discover novel immunomodulators for application in treating autoimmune diseases, a stable Jurkat transfectant was constructed in which luciferase reporter gene is driven by a full-length IL-2 promotor. A chemical library was screened to identify compounds that inhibited luciferase expression in Jurkat transfectants stimulated with PMA and ionomycin. A class of compounds (bis-trifluoromethyl pyrazole, BTPs) was identified from this screen. BTPs were shown to inhibit anti-CD3 and anti-CD28 antibody-induced IL-2 secretion, mixed lymphocyte reaction, and Con A-induced T cell proliferation in normal human peripheral blood T cells. In addition, mRNA levels of IL-4, IL-5, IL-9, IL-10, IL-13, IL-15, and IFN-gamma were markedly inhibited by BTPs in peripheral blood mononuclear cells stimulated by Con A as determined by multi-probe RNA protection assay. Furthermore, IL-2, IL-4, IL-5, and IFN-gamma secretion by Hut 78 cells or CD3(+) T cells stimulated with PMA plus ionomycin or anti-CD3 antibody plus PMA were inhibited in a concentration-dependent manner by BTPs. Therefore, BTPs inhibit a wide spectrum of cytokine production including TH1 and TH2 type cytokines. Taken together, these compounds may be useful for treating autoimmune diseases and organ transplant rejection.     

Effect of dopamine on immune cell proliferation in mice

Dopamine is known as a precursor of catecholamine and one of the neurotransmitters in brain and peripheral tissues. Recent studies suggest an important role of dopamine in immune responses. In the present study, intraperitoneal administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) which lowered endogenous dopamine suppressed splenocyte proliferation in response to mitogens such as lipopolysaccharide (LPS) and concanavalin A (Con A). Moreover, intravenous injection of the specific agonists of dopamine DA-1 receptor (SKF38393) or DA-2 receptor (LY171555) into mice enhanced the splenocyte proliferation stimulated by LPS or Con A. In the in vitro cultures, dopamine, SKF38393 and LY171555 directly promoted cell proliferation to LPS or Con A. These results indicate that dopamine has an ability to regulate B- and T-cell proliferation both in vivo and in vitro.     

Mastocytoma-medicated suppression of mixed lymphocyte culture and mitogen responsiveness.

Murine spleen cells, stimulated in vitro by allogeneic spleen, display a strong proliferative response with the subsequent development of cytotoxic cells. This proliferation and sensitization can be abrogated by the addition of mitomycin-treated or X-irradiated murine DBA/2 mastocytoma cells (P-815). The substance required for this depression of lymphocyte responsiveness is present in the cell-free supernatant fluids of P-815 cultures. The suppression appears to be due to interference with cell proliferation in the mixed lymphocyte culture, because the P-815 also prevents spleen cells from proliferating in response to the mitogens concanavalin A (Con A), lipopolysaccharide (LPS), and phytohemagglutinin (PHA). The significance of these findings is discussed.     

电针大鼠的血清中淋巴细胞转化抑制因子的作用机制分析

本室以前的工作表明:电针(2H_z,3V,30min/d)刺激 SD 大鼠双侧足三里-三阴交,5d后,大鼠血清中产生出淋巴细胞转化抑制因子,本工作对此抑制因子的作用机制进行了初步研究,主要结果如下:(1)电针大鼠的血清不仅显著抑制 Con A 刺激的小鼠淋巴结 T 淋巴细胞转化,还可显著抑制 Con A 刺激的小鼠胸腺细胞和脾脏 T 淋巴细胞转化;同时也发现电针大鼠的血清能显著抑制脂多糖(LPS)刺激的小鼠淋巴结 B 淋巴细胞转化。提示此淋巴细胞转化抑制因子对不同淋巴器官及不同类型的淋巴细胞无选择性作用。(2)将电针大鼠的血清同小鼠淋巴结细胞培养1h,电针大鼠的血清就可显著抑制 Con A 刺激的 T 淋巴细胞转化;将小鼠淋巴结细胞同 Con A 预培养30min,电针大鼠的血清的抑制作用便消失,提示电针大鼠血清中淋巴细胞转化抑制因子作用于 Con A 刺激 T 淋巴细胞活化的早期阶段,同时也排除了此抑制因子的细胞毒作用。(3)电针大鼠的血清显著抑制蛋白激酶 C(PKC)激活剂 PMA和 PMA 加 ca~(2+)通道 A23187刺激的小鼠淋巴结细胞转化,提示淋巴细胞转化抑制因子通过抑制 PKC 的活性或抑制 PKC 介导的细胞活化通路,抑制有丝分裂原刺激的淋巴细胞转化。     

The anti-T cell monoclonal antibody 9.3 (anti-CD28) provides a helper signal and bypasses the need for accessory cells in T cell activation with immobilized anti-CD3 and mitogens

CD28 is an antigen of 44 kDa which is expressed on the membrane of the majority of human T cells. The present study examines the functional effects of an anti-CD28 monoclonal antibody (mAb 9.3) on T cell activation induced with immobilized anti-CD3 mAb OKT3 or with mitogens, in the absence of accessory cells. To this end, we used blood resting T cells that were completely depleted of accessory cells (monocytes, B cells, and natural killer cells), and consequently did not respond to recombinant interleukin-2 (rIL-2), to immobilized OKT3, to PHA, or to Con A. Addition of mAb 9.3 to the cultures enhanced IL-2 receptor expression (Tac antigen) on PHA- or immobilized OKT3-stimulated T cells and induced IL-2 receptors on Con A-stimulated T cells. Moreover, addition of mAb 9.3 to cultures of T cells stimulated with PHA, Con A, or immobilized OKT3 resulted in IL-2 production. Soluble mAb 9.3 was a sufficient helper signal for T cell proliferation in response to PHA or immobilized OKT3. Crosslinking of mAb 9.3 by culture on anti-mouse IgG-coated plates enhanced the helper effect and was an essential requirement for the induction of T cell proliferation in response to Con A. No other anti-T cell mAb (anti-CD2, -CD4, -CD5, -CD7, -CD8) was found to provide a complete accessory signal for PHA or Con A stimulation of purified T cells. T cell proliferation induced by the combination of PHA and mAb 9.3 was strongly inhibited by the anti-IL-2 receptor mAb anti-Tac. In conclusion, mAb 9.3 can provide a signal bypassing monocyte requirement in T cell activation with immobilized OKT3, PHA, and Con A, resulting in an autocrine IL-2-dependent pathway of proliferation.     

Salivary gland extract from Ixodes ricinus tick polarizes the cytokine profile toward Th2 and suppresses proliferation of T lymphocytes in human PBMC culture.

Tick salivary gland extract (SGE) was previously shown to inhibit murine T cell proliferation. In mice, SGE has an inhibitory effect on Th1 and a stimulatory effect on Th2 cytokine elaboration. In the present study, tick-mediated immunomodulation of human T cell proliferation and cytokine elaboration was analyzed using human peripheral blood mononuclear cells (PBMCs) stimulated with concanavalin A (Con A) or lipopolysaccharide (LPS). Using flow cytometry, tick saliva-induced changes were investigated in human mononuclear cell subpopulations. SGE from Ixodes ricinus dose-dependently inhibited human T cell proliferation. This finding supports the flow cytometry data, showing that the percentage of Con A-activated HLA-DR-CD3+ T lymphocytes and CD4+ CD8+ double-positive T cells decreased after SGE treatment. SGE significantly inhibited the in vitro production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) secreted by Th1 lymphocytes. In contrast, the elaboration of IL-4, IL-6, and IL-10 secreted by Th2 lymphocytes was significantly stimulated by I. ricinus SGE. Similarly, the production of both IL-1alpha and IL-1beta was significantly stimulated after SGE treatment. These data indicate that the tick-induced immunomodulatory events in humans are similar to those previously described in a murine model.     

Enhanced macrophage functions and cytokine production of lymphocytes after ingestion of bon narine in female BALB/c mice

The purpose of this investigation was to determine the effects of bon narine treatment on macrophage and lymphocyte functions in mice. Twelve week-old female inbred BALB/c mice were given bon narine p.o. at 30 mg/kg per day and sacrificed after three months. Glucose consumption of peritoneal macrophages in the bon narine treated group during incubation up to 72 h was significantly higher than that in the control group. Activities of acid phosphatase (APH), beta-glucuronidase (GLU) and lactate dehydrogenase (LDH) in the peritoneal macrophages in the bon narine treated group significantly increased compared to that in the control group. Macrophage production of nitric oxide stimulated by lipopolysaccharide (LPS) in the bon narine treated group was significantly increased. Interleukin-1beta (IL-1beta) production of peritoneal macrophages stimulated by LPS was significantly higher in the bon narine treated group. Stimulation indices in splenic lymphocytes by concanavalin A (Con A) in the bon narine treated group were significantly higher than that in the control group. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production stimulated by Con A were significantly increased in the bon narine treated mice. Interleukin-4 (IL-4) production of splenic lymphocytes stimulated by Con A was not different in the control group and the bon narine treated group. These findings might suggest that oral administration of bon narine effectively enhanced the macrophage function and lymphocyte responsiveness in mice.     

Time-dependent inhibition of tuberculin-induced lymphocyte DNA synthesis by a serine protease inhibitor

Diisopropylfluorophosphate (DFP), a group-specific irreversible inhibitor of serine proteases, has been shown to exert time-dependent inhibition of DNA synthesis of lymphocytes stimulated by three different B lymphocyte mitogens: purified protein derivative of tuberculin (PPD), endotoxin protein (EP), and lipopolysaccharide (LPS). The time-dependent inhibition profile found in B lymphocytes is absent in concanavalin A (Con A)-stimulated T lymphocytes. Structural analogs of DFP, which have lost the phosphorylating ability, are not inhibitory. Inhibition of DNA synthesis by DFP is reversible in the first 8 hr of mitogenic stimulation. Maximal and irreversible inhibition by DFP occurs around the 16th hour of stimulation. These data support the postulate that a mitogenesis-linked protease, or proteases, in B lymphocytes is absent in the resting cells but is made available several hours before the initiation of DNA synthesis in the late G1 phase of the cell cycle.     

Characterization of Cell Growth-Inhibitory Factor in Inflammatory Peritoneal Exudate Cells of Rats

We characterized the nature and reaction mode of the cell growth-inhibitory factor (here designated CGIF) from rat peritoneal exudate cells (PEC). The soluble fraction separated from the lysate of Enterococcus faecalis-induced 24 hr PEC completely inhibited Con A-induced thymocyte mitogenesis. Gel filtration chromatography showed that CGIF has a molecular weight of approximately 23–25 kDa. Isoelectric focusing with Rotofor indicates that the factor has an isoelectronic point of 5.8–6.4. CGIF was inactivated by treatment at 70 C, for 30 min or by tryptic digestion, but the activity was not destroyed by the reduction with dithiothreitol. As well as thymocyte proliferation, CGIF completely suppressed ³H-thymidine incorporation of splenocytes which were stimulated by either Con A or LPS, suggesting the factor is effective on both T and B cells. The acting point of the inhibitor appeared to be a later stage of the lymphocyte activation sequence, since it was still effective when added 28.5 hr after the addition of Con A. CGIF also reduced the viability of these cells when added with mitogens such as Con A or LPS. CGIF thus appears to be distinct from interleukin-1 receptor antagonist or transforming growth factor-β.     

Human recombinant interleukin-1 receptor antagonist inhibits lymphocyte blastogenesis induced by concanavalin A. Restorative effect of hrIL-1.

Interleukin-1 (IL-1), mainly produced by monocyte-macrophages, is a polypeptide cytokine with pleiotropic biological effects. IL-1 plays an important role in mediating immune response and inflammation. Recently a natural inhibitor to IL-1 has been discovered, interleukin-1 receptor antagonist (IL-1ra), produced by human monocytes cultured on adherent IgG which binds to the IL-1 receptors. In our study we found that the pretreatment of cells with serial dilutions of IL-1ra (250 ng/ml-2.5 pg/ml) inhibits, in a dose-dependent manner, lymphocyte DNA synthesis stimulated with Con A (10 micrograms/ml). IL-1ra did not have any effect on resting peripheral blood mononuclear cells (PBMC). Time course experiments show that IL-1ra at 250 ng/ml has its maximum inhibitory effect on lymphocyte blastogenesis when cells are pretreated 2 h before Con A. No effect was found when hrIL-1ra was added after Con A. Moreover, hrIL-1ra also inhibits the enhancing effects of exogenous hrIL-1 (400, 200, 100 and 50 ng/ml) on lymphocytes stimulated with Con A; while when hrIL-1ra was used on cells treated with only Con A, the inhibition was more pronounced. When PBMC were removed from monocytes, by adherence, the Con A-treated lymphocytes were not influenced by 2 h pretreatment of hrIL-1ra; while a strong inhibition was found when exogenous hrIL-1 was added at different concentrations. In addition, hrIL-1ra also inhibits the enhancing effect of hrIL-2 on lymphocyte DNA synthesis. In another set of experiments PBMC were pretreated with hrIL-1ra (250 ng/ml) for 2 h and then added LPs (10 ng/ml) and IL-1 alpha generation was determined using ELISA. In these experiments IL-1ra completely abolished the generation of IL-1 alpha. These data suggest that hrIL-1ra exhibits a dose-response inhibition of lymphocyte blastogenesis induced by Con A, probably through the down-regulation of IL-1 synthesis necessary as an early signal for T-cell activation and IL-2 production.     

牛樟芝子实体醇提物对过敏性肺炎的作用

本文研究台湾特有牛樟芝子实体醇提物对过敏性肺炎的作用并探讨其可能的作用机制。体内实验采用卵清蛋白（OVA）致敏制备过敏性肺炎模型,观察各组肺组织病理变化情况,并对脂多糖（LPS）诱导的细胞分泌促炎性细胞因子进行检测;离体实验中采用酶联免疫吸附法（ELISA）对LPS刺激THP-1细胞分泌促炎性因子（IL-1、IL-6及TNF-α）进行了检测。体外巨噬细胞（THP-1）抗炎试验结果显示牛樟芝子实体醇提物不同浓度均可显著抑制LPS诱导的THP-1细胞IL-1的分泌（P<0.001）;可完全抑制IL-6的分泌;浓度20μg/mL及80μg/mL下可以完全抑制TNF-α的分泌。OVA过敏性肺炎动物模型中,与模型组相比,牛樟芝子实体醇提物组可显著改善肺部外观色泽、细支气管淋巴球聚集、肺泡壁增生及肺泡空腔等炎症程度。口服KBA皿式牛樟芝子实体醇提物可有效改善过敏性肺炎程度,并有全身系统性抗炎效果,其机制可能为抑制THP-1细胞IL-1、IL-6及TNF-α的分泌。本研究为深入研究KBA皿式牛樟芝子实体改善雾霾性肺炎提供了重要的实验依据。     

Purinergic modulation of T-lymphocyte activation: differential susceptibility of distinct activation steps and correlation with intracellular 3',5'-cyclic adenosine monophosphate accumulation

The mechanism by which purinergic agonists modulate murine T-lymphocyte activation and proliferation was investigated. Adenosine and other compounds such as ATP and 2-chloroadenosine (ClAdo) were found to block T-cell mitogenesis induced by concanavalin A (Con A) in a dose-dependent fashion. The nonmetabolizable adenosine analog ClAdo was the most potent agent capable of inhibiting T-cell mitogenesis. Extracellular addition of the permeable cAMP analog dibutyryl cyclic AMP (dbcAMP) also led to a dose-dependent blockade of T-cell mitogenesis, although with less efficiency when compared to ClAdo. Addition of IL-2-enriched fluids failed to reverse blockade of T-cell mitogenesis by ClAdo or dbcAMP. ClAdo blocked T-cell enlargement induced after 20 hr of culture with Con A. We analyzed the effect of micromolar concentrations of ClAdo on interleukin-2 (IL-2) production, expression of IL-2 receptors (7D4 and 3C7 surface antigens), and induction of IL-2 responsiveness after in vitro cultivation with Con A. ClAdo inhibited both IL-2 secretion and induction of IL-2 responsiveness up to control levels in the same dose range it inhibited T-cell mitogenesis. However, cell surface expression of IL-2 receptors was not affected. Short incubations of resting splenic T cells with ClAdo led to a dose-dependent accumulation of cyclic AMP in responding cells. This effect was markedly reduced by the purinergic antagonist 3-isobutyl-1-methylxanthine (IBMX) but was not prevented by the adenosine uptake blocker dipyridamole. ClAdo elicited cAMP accumulation in the same dose range it inhibited T-cell activation events. Extracellular administration of dbcAMP to splenic T cells stimulated by Con A mimicked the effects of ClAdo on T-cell activation parameters, as revealed by a dose-dependent blockade of both IL-2 secretion and IL-2 responsiveness induction, without affecting IL-2 receptor expression. Short incubations of Con A-activated T-cell blasts with ClAdo also led to a dose-dependent accumulation of cAMP. We then analyzed the effect of purines and dbcAMP on IL-2-mediated activated T-cell growth. Purines caused a dose-dependent inhibition of IL-2-mediated T-cell proliferation and ClAdo was the most potent purinergic agonist tested. The effect of ClAdo on Con A-induced T blasts was shifted to the right, if compared to earlier T-cell activation steps.(ABSTRACT TRUNCATED AT 400 WORDS)     

Hemorrhage produces abnormalities in lymphocyte function and lymphokine generation

Hemorrhage has been shown to produce abnormalities in lymphocyte function, particularly in the proliferative response to mitogens such as PHA and Con A. In order to better examine the hemorrhage-induced alterations in immune function, we determined the effects of blood loss in mice without any surgical manipulation on lymphocyte populations and subpopulations, cellular activation, and lymphokine production. Hemorrhage induced no changes in cell numbers in the spleen, thymus, lymph nodes, and bone marrow. No alterations in the relative percentages of B (B220+, mu+) and T (Lyt-1+, Lyt-2+, T3+, L3T4+) cell subpopulations were found in any organ after blood loss. Significant decreases in splenocyte proliferation in response to Con A, IL-2R expression and blast formation occurred after hemorrhage. IFN-gamma production increased 24 and 48 h post hemorrhage. Decreases in IL-2, IL-3, and IL-5 generation were present 2 h after blood loss. IL-2 production remained significantly decreased for 48 h posthemorrhage, then increased to more than twice normal levels 72 h posthemorrhage, and subsequently returned to prehemorrhage values. These results demonstrate that hemorrhage produces widespread alterations in immune function without affecting lymphocyte population and subpopulation numbers.     

IFN-gamma stimulates IgG2a secretion by murine B cells stimulated with bacterial lipopolysaccharide

rIFN-gamma strikingly enhances the secretion of IgG2a by murine splenic B cells stimulated with bacterial LPS in vitro and concomitantly suppresses the production of IgG3, IgG1, IgG2b, and IgE while sparing IgM secretion. IFN-gamma stimulates highly purified B cell populations to secrete IgG2a, strongly suggesting that it acts directly on B cells. It increases the frequency of precursors of IgG2a-expressing soft agar colonies and enhances the number of IgG2a+ cells in colonies indicating that it both increases the frequency of precursors of IgG2a+ cells and enhances the number of IgG2a+ daughter cells emerging from each precursor. IFN-gamma completes its action within the first 24 to 48 h of a 6-day culture with LPS and its addition cannot be delayed beyond the first 48 h. Preincubation of resting B cells in the presence of IFN-gamma leads to a time dependent increase, up to 42 h, in IgG2a secretion upon subsequent addition of LPS. IFN-gamma can exert this action on resting B cells that have been selected for absence of membrane IgG expression by cell sorting. The promotion of IgG2a secretion appears to be a specific property of IFN-gamma in that IFN-alpha, IFN-beta, IL-1, IL-2, IL-3, IL-4, IL-5, granulocyte-macrophage-CSF, granulocyte-CSF, and CSF-1 fail to enhance IgG2a secretion by LPS-stimulated B cells.