Characterization of the human blood lymphocytes that produce a histamine-induced suppressor factor (HSF)

The cells which elaborate a soluble suppressor factor in vitro in response to histamine (histamine-induced suppressor factor or HSF) were partially characterized in the present studies. Human blood T- and B-cell populations were purified by affinity chromatography with rabbit anti-human F(Ab′)₂ and examined for their ability to make HSF. Highly purified populations of T cells, but not B cells, produced HSF in response to varying concentrations of histamine (10^?4 to 10^?4M). The HSF-producing cells were characterized further by means of affinity chromatography with columns containing conjugates of insolubilized histamine as well as by rosette formation with IgG (Tγ)- or IgM (Tμ)-coated ox red blood cells. These studies revealed the following: (a) Cells that synthesize HSF are retained on histamine (but not control) columns; (b) cells with histamine receptors comprise approximately 50% of the Tγ subpopulation but are not found in the Tμ subpopulation; (c) cells not retained by histamine columns have a reduced capacity to develop into suppressor cells following stimulation by concanavalin A or specific antigen (compared to unfractionated or control column passed cells). In addition, it was shown that cells synthesizing HSF predominantly express histamine type 2 receptors: (d)4-Methyl histamine (H₂ agonist), but not 2-methyl histamine (H₁ agonist), was capable of inducing HSF production; (e) cimetidine (H₂ antagonist) inhibited HSF production but chlorpheniramine (H₁ antagonist) did not. Taken together, these experiments suggest that T lymphocytes capable of expressing suppressor function following activation by histamine, specific antigen, concanavalin A, or perhaps through their Fc receptors may either be heterogeneous within the same subpopulation or more likely be the same cell with the complement of receptors described above.     

Histamine-induced suppressor factor (HSF): effect on migration inhibitory factor (MIF) production and proliferation.

Histamine added in vitro to cultures of sensitized lymphocytes suppresses antigen-induced production of migration inhibitory factor (MIF) and proliferation by these cells. Recent studies have suggested that lymphocytes bearing histamine type-2 receptors play a regulatory role in these in vitro responses. The present studies were undertaken to determine if suppressor function by cells having histamine receptors was mediated through a soluble product. It was found that lymph node cells from nonimmune or immune strain 2 guinea pigs elaborate a nondialyzable factor into the culture supernatant when incubated with 10(-3) to 10(-5) M histamine (histamine-induced suppressor factor of HSF). HSF, when cocultured with sensitized lymphocytes, suppressed their MIF and proliferative responses to antigen. HSF was made by lymphocytes but not macrophages. Its production could be blocked by an H2 receptor antagonist (burimamide) but not an H1 receptor antagonist (chlorpheniramine). Furthermore, the inhibitory effect of HSF was reversible as lymphocytes washed free of the factor after 24 hr and recultured with fresh medium and antigen were able to produce MIF. Gel filtration by Sephadex G-100 chromatography indicated that HSF had an approximate m.w. of 23,000 to 40,000. These results suggest that the release of histamine at the sites of immediate hypersensitivity reactions, possibly by generating HSF activity, may play a regulatory role in the subsequent development of cellular-immune reactions at the same site.     

Stimulation of prostaglandin E2 and thromboxane B2 production by human monocytes in response to interleukin-2

Interleukin 2 (IL-2) is a potent lymphokine involved in the regulation of immune responses and is classically regarded as a stimulus for the activation and growth of T-cells. Recent reports have demonstrated the IL-2 dependent activation of human peripheral blood lymphocytes into lymphokine activated killer cells capable of lysing tumor cells both in vitro and in vivo. In this study we report data which clearly show IL-2 may also act to down-regulate the immune response by inducing the synthesis of arachidonic acid metabolites with known immunosuppressive actions. Stimulation of peripheral human blood monocytes with IL-2 caused an increased production of prostaglandin E2 (PGE2) and thromboxane (TXB2) in a dose-dependent manner. Kinetic analysis showed no increase above controls after 6 hours and maximal levels by 10 hours; elevated levels were maintained after 45 hours of incubation. After 20 hours of stimulation with 2000 U/ml IL-2, the level of PGE2 and TXB2 were greater than three-fold above controls, 0.7 and 19 ng/10(6) cells, respectively. The stimulation was relatively specific in that neither prostacyclin nor leukotrienes were produced in response to IL-2. These data demonstrate that IL-2 acts on human monocytes to induce the secretion of PGE2 and TXB2.     

Properties of histamine-induced suppressor factor in the regulation of lymphocyte response to PHA in mice

Splenic T lymphocytes release a suppressor factor into the culture supernatant when incubated for 24 hr with histamine (10^?4M). Histamine-induced suppressor factor (HISF) inhibits lymphocyte response to PHA; it is released by T lymphocytes (either nylon-nonadherent or nylon-adherent lymphocytes) and not by B-cells or macrophages; its production is not observed after depletion of histamine receptor-bearing lymphocytes and is blocked by the H2 receptor antagonist (cimetidine) but not by the H1 receptor antagonist (diphenhydramine). Gel filtration by Sephadex G100 chromatography indicates that HISF had an approximate MW of 45,000 to 68,000. Its inhibitory activity was removed by passage over a histamine RSA-Sepharose column, but not by passage over rabbit anti-mouse Ig-Sepharose column; it was blocked by prostaglandin synthetase inhibitor (PGS) (Ro 205720) indicating that this activity is mediated by a prostaglandin (PG) synthesis.     

Allogenic stimulus induces prostaglandin and thromboxane production in T lymphocytes

We have examined the influence of an allogeneic stimulus on T lymphocyte prostanoid synthesis. PGE2 and TXB2 (the stable product of TXA2) were determined by radioimmunoassay. When T cells were derived from alloimmunized animals, the production of PGE2 and TXA2 was significantly higher than that of non-immunized cells. Moreover, T immune lymphocytes in the presence of the immunized alloantigen showed an increment in prostanoid production. We propose that the allogeneic stimulus provides a signal to the T lymphocytes for an increase in prostanoid synthesis.     

Increased production of tumor necrosis factor and prostaglandin E2 by monocytes in cancer patients and its unique modulation by their plasma

Summary We investigated the role of monocytes in the production of tumor necrosis factor (TNF) and prostaglandin E₂ (PGE₂) in 77 cancer patients with malignancies of the digestive tract, using 30 normal individuals and 18 noncancer patients as controls. Monocytes were incubated with lipopolysaccharide for 20 h, and TNF production and PGE₂ production were analyzed by bioassays. Elevated levels of TNF (>512 U/ml) and PGE₂ (>8 ng/ml) production were demonstrated in many cancer patients when these factors were induced in the medium with 10% fetal bovine serum. The elevated level of TNF was seen to be restricted for the most part to patients with malignancies. Thus, 51 out of 59 cancer patients (86%), consisting of 44 primary cancer patients and 15 recurrent cancer patients, showed an increased level of TNF. In contrast, almost all of 18 postoperative cancer patients showed TNF levels comparable to those of normal individuals. Furthermore, 16 primary cancer patients were also demonstrated to have reduced levels of TNF production by monocytes after curative operation. When 10% cancer-patient plasma was added to the induction culture, TNF production by monocytes was drastically suppressed in the cancer patients. Interestingly, the same addition of plasma induced a prominent enhancement of PGE₂ production in the cancer patients. The plasma of noncancer patients did not modulate production of these factors. No TNF activity was found in the plasma of cancer patients, but such plasma did contain an increased level of PGE₂ (100–300 pg/ml). Although PGE₂ (>2ng/ml) was able to suppress TNF production by monocytes, the addition of 10% plasma PGE₂ was not enough to induce suppression. An unknown factor(s) in the plasma of cancer patients may uniquely modulate the elevated TNF and PGE₂ production in these patients.     

Induction of proliferation of human circulating monocytes in vitro by lectin-induced factor(s) from lymphocytes

Human peripheral blood monocytes, which have been considered to be non-dividing cells, were induced to proliferate in vitro by soluble mediator(s) from lectin-activated human lymphocytes. The lectin-induced factor from lymphocytes increased both the number of nuclei of cultured monocytes and [3H]-thymidine incorporation into the monocytes. The molecular weights of the soluble factor(s) that promote growth of monocytes were in the range of 20,000-70,000 daltons with two peaks.     

Differential regulation of prostaglandin E2 and thromboxane A2 production in human monocytes: implications for the use of cyclooxygenase inhibitors

There is an autocrine relationship between eicosanoid and cytokine synthesis, with the ratio of prostaglandin E2 (PGE2)/thromboxane A2 (TXA2) being one of the determinants of the level of cytokine synthesis. In monocytes, cyclooxygenase type 1 (COX-1) activity appears to favor TXA2 production and COX-2 activity appears to favor PGE2 production. This has led to speculation regarding possible linkage of COX isozymes with PGE and TXA synthase. We have studied the kinetics of PGE2 and TXA2 synthesis under conditions that rely on COX-1 or -2 activity. With small amounts of endogenously generated prostaglandin H2 (PGH2), TXA2 synthesis was greater than PGE2. With greater amounts of endogenously generated PGH2, PGE2 synthesis was greater than TXA2. Also, TXA synthase was saturated at lower substrate concentrations than PGE synthase. This pattern was observed irrespective of whether PGH2 was produced by COX-1 or COX-2 or whether it was added directly. Furthermore, the inhibition of eicosanoid production by the action of nonsteroidal anti-inflammatory drugs or by the prevention of COX-2 induction with the p38 mitogen-activated protein kinase inhibitor SKF86002 was greater for PGE2 than for TXA2. It is proposed that different kinetics of PGE synthase and TXA synthase account for the patterns of production of these eicosanoids in monocytes under a variety of experimental conditions. These properties provide an alternative explanation to notional linkage or compartmentalization of COX-1 or -2 with the respective terminal synthases and that therapeutically induced changes in eicosanoid ratios toward predominance of TXA2 may have unwanted effects in long-term anti-inflammatory and anti-arthritic therapy.     

Immune-complex induced prostaglandin production by monocytes of normal human subjects and cancer patients

Isolated cultures of mononuclear phagocytes from 12 humans (7 normal controls and 5 with cancer) produced prostaglandins (PGs) of the E series when stimulated with artificial immune complexes (HSA and anti-HSA). The amount of PGs produced by monocytes from breast cancer patients and macrophages from ascites fluid taken from patients with abdominal cancers was 4 fold that produced by blood monocytes from normal controls. Immune complex (IC) determinations from the serums of these humans (Raji cell method) showed that only patients in the advanced stages of the diseases, and none of the controls, had elevated levels of IC. In the presence of IC, there was noted a depression in the immune reactivity of mononuclear cell cultures, as determined by ³H thymidine uptake following stimulation with PHA, Con A and PWM. The depressed blastogenic response was not in all instances fully reversed by the addition of indomethacin or aspirin, indicating that PGs were not the only causative factor. It is concluded that mononuclear phagocytes elaborate immunosuppressive factors in response to stimulation by immune complexes. One of these factors is PGE. Further, this results in a homeostatic regulation which prevents damage from IC deposition and may be, in part, responsible for immunosuppression of cancer patients.     

Effect of peroxisome proliferator-activated receptor gamma on thromboxane A(2) and prostaglandin E(2) production in macrophage cell lines

We studied the effect of peroxisome proliferator-activated receptor gamma (PPARgamma) activation on thromboxane A(2)(TXA(2)) and prostaglandin E(2)(PGE(2)) production in monocyte/macrophage cell lines. In present experiment, we used human peripheral blood monocyte (PBMC), monocyte-cell line THP-1 and mouse macrophage-like cell line RAW264.7. The expression of PPARgamma is reported in PBMC and THP-1. Synthetic PPARgamma ligands (troglitazone or BRL49653) inhibited TXA(2) production and enhanced PGE(2) production of PBMC and THP-1. When treated with 0.5-10 microM of troglitazone, there were no significant changes of TXA(2) and PGE(2) production of RAW264.7 cells, which express very low levels of PPARgamma. When RAW264.7 cells was transfected with PPARgamma expression plasmid and treated with troglitazone, PPARgamma was activated in a dose-dependent manner. In PPARgamma-transfected RAW264.7, TXA(2) production was decreased and PGE(2) production was increased by troglitazone treatment. But it needs high concentration of troglitazone (10 microM) for increasing PGE(2) production. These results suggest that PPARgamma may have negative effect on TXA(2) production, and also have slightly positive effect on PGE(2) production of macrophage.     

Specific production of prostaglandin E by human amnion in vitro

Prostaglandin production by intra-uterine human tissues has been investigated using a method of tissue superfusion. Tissues were obtained at elective Caesarean section and after spontaneous vaginal delivery. It was found that all the tissues studied (amnion, chorion, decidua and placenta) produced more prostaglandin E (PGE) and 13,14-dihydro-15-keto-prostaglandin F (PGFM — the major circulating metabolite of prostaglandin F) than prostaglandin F (PGF). Amnion produced significantly more PGE (but not PGF or PGFM) than any other tissue. Prostaglandin production by each tissue was similar whether it was taken at elective Caesarean section or after spontaneous vaginal delivery.     

Histamine-induced suppressor factor (HSF): further studies on the nature of the stimulus and the cell which produces it.

Guinea pig lymphocytes are stimulated by histamine to produce a soluble factor with immunosuppressive properties. This factor, termed histamine-induced suppressor factor or HSF, abrogates the production of migration inhibitory factor (MIF) and proliferative response to specific antigen. In the present study we have determined the lymphocyte subpopulation which elaborates HSF, the lymphoid tissue source, the kinetics of its generation in relation to immunization, and the nature of the histamine receptor involved in modification of the release of HSF. HSF activity could be detected in populations of cells from spleen and lymph nodes prior to active immunization of the donor, but not in cells from the donor's blood or thymus. Following immunization with ortho-chloro benzoyl-bovine γ-globulin in complete Freund's adjuvant (CFA), more HSF activity was detected in cells from the donor's spleen and lymph nodes. The peak response was seen 2 weeks postimmunization when significant amounts of HSF also were made by cells from the blood and thymus. Concentrations of T-cell-enriched and B-cell-enriched populations were tested for their ability to make HSF. We found that T-cell-enriched, but not B-cell-enriched populations, made significant amounts of HSF. Cells from the lymph nodes of immunized donors were chromatographed over affinity columns made of insolubilized conjugates of histamine with albumin. The nonretained cells were unable to generate HSF, whereas HSF activity was detected in the cells that were retained by the columns. This finding strongly suggests that the HSF-producing cells have receptors for histamine. Cells from CFA-immune lymph nodes were incubated with H₁ (2-methyl histamine) and H₂ (4-methyl histamine) agonists to determine their relative potency and, therefore, the nature of the histamine receptors on these cells that were modifying HSF release. Although both agonists could induce generation of HSF when high concentrations (10^?3M) were used, only the H₂ agonist stimulated production or release of HSF at lower concentrations (10^?5M). These HSF-producing cells appear to be selectively sensitive to H₂ agonists and likely have a predominance of H₂ receptors. Allergic mediators other than histamine were studied to determine their ability to allow elaboration of HSF-like activity from CFA-immune lymph node cells. Serotonin (10^?3M), slow-reacting substance of anaphylaxis (100 units/ml), eosinophil chemotactic factor (tetrapeptide; 10^?5M), and prostaglandin E₁ (10^?4M) were unable to induce HSF-like activity in lymph node cells from donors immunized with CFA. Furthermore, other agents which raise intracellular levels of cyclic adenosine 3′,5′-monophosphate (cyclic AMP) such as isoproterenol and cholera toxin, as well as the dibutyryl form of cyclic AMP itself, were also unable to generate HSF-like activity. Thus, histamine is unique among the allergic mediators in stimulating elaboration of the suppressive substance. These findings also suggest that the ability of histamine to stimulate HSF may not reside in the conventional pathway linked to cAMP accumulation, but rather to an as yet undefined pathway of cell activation. A model is presented which further implicates histamine as a modulator of cellular immune reactions.     

Augmentation of prostaglandin E2 production by mammalian phospholipase A2 added exogenously.

Rat group II phospholipase A2 added exogenously to A23187-activated HL-60 granulocytes augmented their production of prostaglandin E2. Human group II phospholipase A2 and porcine group I phospholipase A2 augmented the prostaglandin E2 production in a similar manner. No significant increase in prostaglandin E2 production was observed when cells were treated with purified phospholipase A2 in the absence of A23187. Extracellular phospholipase A2 at inflamed sites may contribute to the generation of pro-inflammatory lipid mediators by hydrolyzing the cellular phospholipids of activated inflammatory cells.     

Examination of survival, proliferation and cell surface antigen expression of human monocytes exposed to macrophage colony-stimulating factor (M-CSF)

The effects of macrophage colony-stimulating factor (M-CSF or CSF-1) on the survival, proliferation, maturation and activation of human blood monocytes were examined. M-CSF (100-1,000 U/ml) doubled the number of monocytes surviving after eight days in culture and accelerated the usual increase in cell volume. Antiserum to M-CSF abolished both of these effects. There was no sizable increase in 3H-thymidine incorporation in monocytes over this time period. Of various factors tested, including gamma-interferon (gamma-IFN), interleukin (IL) 1 alpha, granulocyte CSF (G-CSF), platelet-derived growth factor (PDGF), and lipopolysaccharide (LPS), only granulocyte-macrophage CSF (GM-CSF) could also enhance survival and augment cell volume. While antiserum to human M-CSF eliminated the increase in survival induced by GM-CSF, it could not ablate the GM-CSF-stimulated increase in monocyte cell volume. Monocyte cell surface markers that increase with maturation (i.e., Fc gamma RIII) or with activation (i.e., Fc gamma RI) were unaffected by incubation with M-CSF.     

Platelet-activating factor induces the production of leukotrienes by human monocytes

The aim of this study was to evaluate the role of platelet-activating factor (PAF) as a stimulator of leukotriene production by human monocytes. The production of leukotrienes was time- and concentration-dependent. Release of leukotrienes was half-maximal after 2 min and reached a maximum after 10 min. At a concentration of 10(-8) M, PAF induced the production of 0.14 +/- 0.01 ng LTB4/10(6) cells (mean +/- S.E., n = 8). At concentrations of 10(-6) M, PAF induced the production of 1.0 +/- 0.04 ng LTB4 and 0.22 +/- 0.03 ng peptidoleukotrienes (mean +/- S.E., n = 16). There was no metabolism of LTB4 as judged from stability of [3H]LTB4 added to the incubations. LTC4 was slowly metabolized by human monocytes to LTD4 and LTE4. The two specific PAF-receptor antagonists BN 52021 and WEB 2086 in concentrations of 10(-4) and 10(-6) M, respectively, inhibited the PAF (10(-6) M) stimulated LTB4 production completely. In this study, we demonstrate that nanomolar concentrations of PAF can stimulate the production of LTB4 and peptidoleukotrienes in human monocytes by a receptor-mediated mechanism.     

Further studies on prostaglandin and thromboxane production by the rat uterus during the oestrous cycle

Prostaglandin (PG) and thromboxane (TX) synthesis by uterine homogenates was measured at 4-h intervals during the 4-day oestrous cycle of rats. Production was in the order of 6-oxo-PGF-1 alpha (which reflects PGI-2 synthesis) greater than PGF-2 alpha greater than TXB-2 (which reflects TXA-2 synthesis) greater than or equal to PGE-2. Peak production occurred at 02:00 h on the day of oestrus, after which production gradually decreased, with some fluctuation on the day of metoestrus, to reach a minimum between 22:00 and 06:00 h on the days of dioestrus and oestrus, respectively. Separation of the uterine tissues showed that, on a unit weight basis, the endometrium had a much higher PG and TX synthesizing ability than did the myometrium, although this was compensated for on a total weight basis by the much greater mass of myometrium. Endometrial PG and TX production was in the order of PGF-2 alpha greater than TXB-2 greater than or equal to 6-oxo-PGD-1 alpha identical to PGE-2, with PGF-2 alpha and TXB-2 productions showing the greatest increases between 10:00 and 02:00 h on the days of pro-oestrus and oestrus, respectively. Myometrial PG and TX production was in the order of 6-oxo-PGF-1 alpha greater than PGF-2 alpha greater than PGE-2 identical to TXB-2, with 6-oxo-PGF-1 alpha and PGF-2 alpha productions showing small increases between 10:00 and 02:00 h on the days of pro-oestrus and oestrus, respectively. Myometrial PGE-2 production decreased between these two times.(ABSTRACT TRUNCATED AT 250 WORDS)