Influence of endotoxin on production of leucocyte migration inhibition factor. Part I

Commercial reagents are often contaminated with endotoxins in concentrations which may affect biological immunoassays. The endotoxin lipopolysaccharide from E. coli 026:B6, at concentrations at and above 5 X 10(-9) g/ml induces mononuclear cells to produce the lymphokine leucocyte migration inhibition factor (LIF). However, lipopolysaccharide at concentrations at or above 5 X 10(-8) inhibit leucocyte migration making it impossible to measure the effect of LIF. Standardization of endotoxin content during production and assay of LIF is needed, in order to reduce the variability of the results.

Effects of leukotrienes on neutrophil migration, and on production and action of lymphokines

The effect of the leukotrienes LTB4, LTC4 and LTD4 on the production of the lymphokine leukocyte migration inhibitory factor (LIF) from human peripheral blood mononuclear cells was tested. LTC4 and LTD4 failed to influence LIF production by cells stimulated by antigen or the polyclonal T cell activator, phytohemagglutinin (PHA). LTB4, at concentrations 10(-7) to 10(-6) M, showed significant inhibition of antigen-induced LIF production but was without effect when cells were stimulated by PHA. The cell levels of cyclic adenosine monophosphate (cAMP) were unaffected by 2.5 X 10(-7) M LTB4 in the absence or presence of theophylline. These results indicate that LTB4 acts on the early effector stage of the immune response without affecting the cellular cAMP content.

Mechanism of action of cyclosporin A. Effect on T-cell-binding of interleukin 1 and antagonizing effect of insulin

Previous studies have shown that cyclosporin A (CyA) prevents the elaboration of the lymphokine leucocyte migration inhibitory factor (LIF). Since LIF production is interleukin 1 (IL-1)-dependent, we carried out experiments using partially and highly purified IL-1 preparations to study the effect of CyA. We found that (a) IL-1 was consistently depleted during a 1-h incubation with human blood T lymphocytes but not with B lymphocytes or erythrocytes; (b) the depletion could not be ascribed to pinocytosis, cell functions requiring active metabolism, or enzyme-mediated destruction of IL-1; (c) CyA, but not biologically inactive cyclosporin, antagonized the apparent absorption of IL-1; (d) T cells pre-exposed to CyA were rendered incapable of removing the monokine; and (e) CyA was capable of displacing IL-1 once absorbed by T cells. Because the putative binding of IL-1 showed saturability, reversibility (with CyA as a probe), and tissue specificity consistent with a known target for the monokine, we propose that IL-1 interacts with a receptor-like structure on T cells. Finally, we found that insulin interfered with the function of CyA at the very early macrophage-T-cell co-operative stage, even at physiological concentrations.

Antigenicity and protein content of perilymph in acoustic neuroma patients

11 acoustic neuroma patients, exhibiting cell-mediated immunity in vitro against acoustic neuroma extract, were tested for cell-mediated immunity in vitro against perilymph samples from other acoustic neuroma patients. 14 of 21 perilymph samples were antigenic. None of three healthy persons reacted against antigenic perilymph samples. The perilymph antigenicity was reproducible and negatively correlated to the perilymph sample volume. Differences in sample volume could not be ascribed to admixture of endolymph, cerebrospinal fluid, plasma or blood. The perilymph protein concentration varied from 31 to 54 g/l. Gel electrophoresis of perilymph proteins revealed less staining in the alpha-region compared to plasma proteins and a distinct band in the pre-gamma region absent in plasma. Tau-transferrin was not detected in any of 13 samples. The findings support that the cell-mediated immune response against acoustic neuroma extract may be mediated through release of antigen(s) to the perilymph.

Production of leukocyte migration inhibitory factor (LIF) in human lymphocyte subsets exposed to polyclonal activators

Lymphocyte subsets separated on the basis of nylon-wool adherence and E and EA rosetting, and characterized for the presence of esterase-positive phagocytic cells were investigated for production of leukocyte migration inhibitory factor (LIF) in response to polyclonal T- and B-cell activators, PHA, ConA, PWM, and Epstein-Barr virus (EBV). In the nylon-passed population only the high avidity E+EA+ cells responded to ConA, PHA-induced LIF production in all E-rosetting subsets. The nylon-adherent E+ subset, which contains activated T cells, produced LIF spontaneously. B cells produced LIF when exposed to PWM or uv-inactivated EBV. In accordance with the known T-cell dependence of PWM activation, LIF was detected only in supernatants of reconstituted populations containing both B and T cells. In contrast, uv-inactivated EBV, devoid of transforming potential, elicited LIF production in the pure B-cell population. LIF production in response to polyclonal activators seemed to be independent of accessory cells since reconstitution with autologous macrophages or semipurified monokine, high-molecular-weight Interleukin 1 (IL-1), did not alter the results.

A standardized human T-lymphocyte proliferation assay for detecting soluble accessory factors from monocytes. I. Monocyte and monokine requirements

Monocyte (M phi-) depleted human peripheral blood mononuclear cells exhibit reduced capacity to proliferate, when stimulated with low doses of phytohaemagglutinin (PHA). Stimulation with higher doses of the mitogen or addition of graded numbers of autologous M phi's potentiated the response proportionally, and 10% M phi's restored the response completely. Addition of only 0.1% M phi's was needed for potentiating the response significantly. Pretreatment of M phi's with Actinomycin-D or heating impaired the accessory effect, whereas x-irradiation had no effect. The presence of M phi's did not influence the viability of the proliferating lymphocytes. Crude supernatants from M phi-cultures, even at very low concentrations, partly restored the PHA response, as did preparations of highly purified human Interleukin-1.

EGNA-specific LIF production of human lymphocyte subsets

Using the indirect leukocyte migration inhibition technique T cells have been identified as being responsible for Epstein-Barr virus nuclear antigen-induced specific leukocyte migration inhibitory factor production. The response was dependent on the presence of macrophages or their product, T-lymphocyte activating factor.

Role of monocytes/macrophages and interleukin 1 in antigen-induced human lymphokine production

The monocyte/macrophage (M phi)-dependency for antigen-induced production of the lymphokine, leukocyte migration inhibitory factor (LIF), was investigated using a M phi pulse-exposure technique. M phi-depleted, purified T lymphocytes did not elaborate LIF in response to the recall antigen, tuberculin (PPD). Addition of M phi's pulsed with PPD rectified the response. Exposure of the M phi's down to 3 min, even at 0 degree C, was efficacious. PPD-exposed M phi's, either killed or rendered incapable of protein synthesis, failed to activate the T cells. However, PPD-exposed, killed M phi's triggered LIF production if exogenous interleukin 1 (IL-1) was provided. We suggest that M phi "presentation" of antigen in this test system is a passive albeit necessary, process; the requirement for M phi metabolism being confined to the elaboration of IL-1. Judged by the results of kinetic experiments, the latter stimulus appears to be mediated most effectively from 2 to 4 hr after antigenic challenge.

Lymphocyte function and chromosome aberrations in patients with early mycosis fungoides and parapsoriasis en plaques

Thirteen patients with stage I or II mycosis fungoides (MF) and 10 patients with large-plaque parapsoriasis en plaques (PEP) were examined for immunologic and cytogenetic disturbances. Total lymphocyte counts and immunoglobulin concentrations in the blood were normal. In vitro lymphocyte responses to polyclonal activators and various antigens in standard concentrations were normal. However, titration of phytohemagglutinin and concanavalin A (ConA) disclosed significantly lowered responses to suboptimal concentrations in the patient group, most pronounced in patients with MF II. ConA-induced leukocyte migration inhibitory factor (LIF) production, tested in an indirect leukocyte migration inhibitory assay, was low in the patient group. Furthermore spontaneous LIF production in vitro and small amounts of serum LIF were demonstrated in a few patients. The chromosomal banding pattern, sister chromatid exchange, and break frequency were within normal limits except for 3 translocations in the MF group. It is concluded that even in early-stage MF a pathologic function of blood lymphocytes can be demonstrated, when sensitive methods are applied. The findings might be important for monitoring disease activity and effect of treatment.

Specific cellular immunity in acoustic neuroma patients

An indirect leukocyte migration agarose technique to detect cell-mediated immunity was modified to obtain a specific assay for release of human leukocyte migration inhibitory factor. Acoustic neuroma patients exhibited a significant cellular immune response against acoustic neuroma extract (P less than .01) as well as perilymph from acoustic neuroma patients (P less than .01) when compared to healthy control persons. All 19 patients tested reacted to acoustic neuroma extract. Seven of 21 perilymph samples did not elicit migration inhibition. Crossover determination of antigenicity of two negative and four positive perilymph samples against three patients revealed highly reproducible results, uncorrelated to perilymph concentration of potassium and protein. Flow cytofluorometry did not reveal malignant DNA patterns in 10 acoustic neuromas examined. Immunofluorescence studies did not reveal autoantibodies against acoustic neuromas in sera from 11 patients. The responsible antigen(s), the mechanism of immunization, and the diagnostic implications remain to be determined.

Effects of cyclosporin A (CyA) and methylprednisolone (MP) on the immune response. II. Further studies of the monocyte - T cell interactions leading to lymphokine production

The immunosuppressive drugs cyclosporin A (CyA) and methylprednisolone (MP) abolished the elaboration of the lymphokine leukocyte migration inhibitory factor (LIF) by mononuclear cells challenged by recall antigen. Suppression in both cases was reversible upon removal of the drugs, and participation of T suppressor cells of their mediators could not be demonstrated. The CyA-induced effect was exerted in the early stage of lymphocyte activation (less than 60 min), whereas MP still inhibited LIF release when added 60 min after the antigen. In contrast to earlier findings that the drugs failed to affect the release of T cell-activating factor (TAF) and lymphocyte-activating factor (LAF) from macrophages (M-phi's) stimulated by phorbol myristate acetate. MP (but not CyA) markedly reduced TAF production by M-phi's incubated with tuberculin. M-phireover, partially purified TAF and LAF both restored LIF production in the presence of CyA (but not MP), an effect not mimicked by the T cell product T cell growth factor. However, suppression by both drugs was abrogated by exogenous cGMP. Hence, CyA seems to obstruct the interaction between TAF/LAF and the immune T cell, whereas MP affects antigen-induced T cell activation at the Mo level as well as the level of lymphokine production and/or release. The effects of both drugs seem related to intracellular events involving cGMP.

Immunosuppressive actions of gold salts

In rheumatoid arthritis both lymphocyte-mediated and antibody-mediated immune reactions are important for the inflammatory lesions. In vivo activated B lymphocytes/plasma cells, T lymphocytes and monocytes/macrophages (Mo) are intimately involved in the disease process. Several clinical observations suggest an immunosuppressive action of gold salts. In humans, gold salts interfere with a number of Mo functions in vitro, including cellular interactions between Mo and T lymphocytes. Some workers have shown that the activation of human T lymphocytes is inhibited by gold salts, most probably secondary to an inhibition of Mo-T cell cooperation. Recent experiments indicate that gold salts also affect the in vitro differentiation of human B lymphocytes in response to polyclonal activators. Both the gold atom and the SH group seem to be important for the immunosuppressive actions of gold salts.

Effect of cyclosporin A (CyA) on the immune response. CyA competitively inhibits the function of monocyte/macrophage-derived T-lymphocyte-activating factor(s)

The mechanism of action of the immunosuppressive drug, cyclosporin A (CyA), was analyzed with respect to antigen-induced production of the human lymphokine, leukocyte migration inhibitory factor (LIF). Mononuclear cells as well as purified T-cells did not elaborate LIF in the presence of pharmacological concentrations of CyA. CyA-induced immunosuppression was competitively reversed by addition of the partially purified monokines, T-cell-activating factor (TAF) and lymphocyte-activating factor (LAF). CyA did not affect T-cell priming with antigens. The drug failed to abolish LIF production if added 60 min after challenge of T-cells with recall antigen in the presence of TAF. Furthermore, addition of TAF within 15 min to CyA-treated T-cells resulted in unaltered LIF production. These results suggest that CyA suppresses the early stage of the immune response by competing with the function of TAF/LAF on the immune T-cell.

Patient-specific cell-mediated immunity against human acoustic neuroma extract

Lymphocytes from 8 patients with acoustic neuromas and 8 healthy control persons were exposed to acoustic neuroma extract. Indirect leukocyte migration agarose technique was applied for detection of leukocyte migration inhibition (LMI). The standard technique was additionally modified using a specific assay for release of human leukocyte migration inhibitory factor (LIF). Both the standard technique and the LIF-specific assay revealed a significant LMI exerted by lymphocytes from patients, as compared with control persons. The LIF-specific assay demonstrates that the LMI is an expression of cell-mediated immunity due to release of LIF. The immune reaction is raised against an unknown antigen in acoustic neuroma extract. Further studies must determine whether the immune reaction is specific for acoustic neuroma patients vis-a-vis patients with other tumours, especially other neuromas.

Effects of cyclosporin A (CyA) and methylprednisolone (MP) on the immune response. I. T-cell-activating factor abrogates CyA- but not MP-induced suppression of antigen-induced lymphokine production

The influence of cyclosporin A (CyA) and methylprednisolone (MP) on the elaboration of the human lymphokine, leukocyte migration inhibitory factor (LIF) was investigated. Both CyA and MP at pharmacological concentrations inhibited the release of LIF from immune lymphocytes challenged by recall antigen. By contrast, the release of LIF in response to polyclonal activation by phytohaemagglutinin A was not affected by CyA or by MP. CyA and MP had no effect on the production of the monokine, T-lymphocyte-activating factor (TAF) by stimulated blood monocytes. However, addition of partially purified TAF to antigen-stimulated lymphocytes completely abrogated the inhibitory effect of CyA, but not that of MP. Thus, CyA and MP affect antigen-induced production of LIF by immune lymphocytes by different mechanisms.

Involvement of monokines in antigen- and lectin-induced human lymphokine production

To analyze the role of monocytes/macrophages (Mø's) in the activation of human lymphocytes, suspensions enriched in T cells and markedly depleted of Mø's were prepared. The Mø-depleted cells challenged by tuberculin did not elaborate the lymphokine, leukocyte migration inhibitory factor (LIF). This reduction in LIF production was negatively correlated to the proportion of residual Mø's being complete in the presence of less than 2% Mø's. In contrast, the LIF response to the polyclonal activator, phytohemagglutinin A, was unimpaired by Mø depletion. LIF production of the Mø-depleted cells could be fully reconstituted by addition of conditioned media obtained from Mø cultures, especially if stimulated by the Mø-activating agent, phorbol myristate acetate. This effect was dose-dependent and could be ascribed to molecules of molecular weights 80K and 12K, respectively.

Studies on the active site of human leukocytic pyrogen

Leukocytic pyrogen, a polypeptide produced by phagocytic mononuclear cells, is thought to be the endogenous mediator of fever. In addition to its effects on thermoregulation, leukocytic pyrogen has been shown to induce synthesis of acute-phase proteins, increase lymphocyte blastogenesis to mitogens, and cause release of neutrophil-specific granule contents. Despite its important role in biologic responses, little is known concerning the structure-function relationship of the molecule. In the present studies several protein-modifying conditions were used in order to examine specific amino acid participation at the active site. Because the state of purity of leukocytic pyrogen may be critical during certain reaction conditions, highly purified preparations were used. Experiments suggest that the active site requires the gamma-carboxyl group of glutamic acid and that blocking arginine reduces both the pyrogenic and neutrophil releasing properties of the molecule. Other studies demonstrate that the pyrogenicity of human leukocytic pyrogen is not due to serine esterase or carboxypeptidase B activity and that the 15,000-dalton molecule may be a glycoprotein. These experiments provide further evidence that the lymphocyte-activating and neutrophil-granule-releasing properties of human leukocytic pyrogen require the same active site which produces fever.

Functional characteristics of synovial fluid and blood mononuclear cells in rheumatoid arthritis and traumatic synovitis

The activity of blood mononuclear cells (BMC) and synovial fluid mononuclear cells (SMC) from patients with rheumatoid arthritis (RA) and traumatic synovitis (TS) was assessed by means of [14C]thymidine incorporation and production of leukocyte migration inhibitory factor (LIF). When compared with normal controls, spontaneous LIF production by BMC was found in 5 of 9 TS patients, whereas spontaneous LIF production by rheumatoid arthritis BMC and by SMC from both patient groups was infrequently seen. ConA-induced LIF production by BMC and SMC from both patient groups did not differ significantly from that of normal controls. Thymidine incorporation by unstimulated SMC and BMC was low in both patient groups. After stimulation with polyclonal activators, SMC showed significantly reduced proliferation in comparison with BMC, but the responses to microbial antigens were equal to or higher than those of BMC. The proliferative responses of stimulated SMC from TS patients were higher than the responses displayed by stimulated SMC from RA patients.