The production of heterologous antibodies to the human lymphakine: leukocyte migration inhibitory factor (LIF)

Hypersensitivity of delayed type in hypertensive patients

The agarose migration technique was used for demonstration of delayed-type hypersensitivity to arterial vessel wall antigens in patients suffering from chronic essential hypertension. By means of this technique, it was demonstrated that the migration indices from the hypertensive patients differed significantly from the normotensive control persons, P less than 0.005. The significant difference was abolished when anti-LIF was added to the migration tests. This means that a hypersensitivity of the delayed type had developed in the hypertensive patients and the results indicated that the hypersensitivity was an autoimmunity to arterial vessel wall antigens.

Duration of delayed-type autoimmunity against arterial vessel-wall antigens following acute hypertensive damage to arterial vessels in rats

Acute hypertensive damage to small arteries and arterioles in rats was induced by intravenous injections of Hypertensin. The in vitro immunological method of the agarose migration technique was used to demonstrate delayed-type autoimmunity against arterial vessel-wall antigens. By this technique the autoimmunity could be demonstrated for about 16 weeks after the acute hypertensive damage to the arterial vessels. The results of the autoimmunity were given as migration indices. These were lowest during the first 4-5 weeks after the damage to the vessels whereupon they showed higher and higher values, and finally the migration indices were identical with those of the control rats after about 16 weeks.

Mechanisms of pancreatic islet cell destruction. Dose-dependent cytotoxic effect of soluble blood mononuclear cell mediators on isolated islets of Langerhans

Supernatants of peripheral blood mononuclear cells from healthy human donors stimulated with recall antigen (purified protein derivative of tuberculin) or lectin (phytohaemagglutinin) markedly inhibited the insulin release from isolated human and rat islets of Langerhans, and decreased rat islet contents of insulin and glucagon in a dose-dependent manner. A maximal effect on islet function was obtained with supernatant concentrations down to 5%. Supernatants of mononuclear cells stimulated with tuberculin were more potent than supernatants produced by lectin stimulation. Culture medium reconstituted with tuberculin or phytohaemagglutinin did not impair islet function. Electron microscopy demonstrated that supernatants were cytotoxic to islet cells. The cytotoxic mononuclear cell mediator(s) was non-dialysable, sensitive to heating to 56 degrees C, labile even when stored at -70 degrees C, but stable when lyophilised.

The indirect leucocyte migration inhibition assay--an endotoxin-sensitive chemokinetic assay. Part II

Depletion of agarose for endotoxins resulted in a low spontaneous migration of polymorphnuclear cells (PMNC). Re-addition of endotoxin, in casu lipopolysaccharide from E. coli 026:B6 (LPS), enhanced the spontaneous PMNC migration in a two-phased dose-response pattern, reaching maximum migration with LPS 1 x 10(-7) g/ml. Thus, the migration of PMNC under agarose seems to be a chemokinesis. Leucocyte migration inhibition factor (LIF), induced by PPD 50 micrograms/ml at endotoxin-free conditions, significantly reduced the PMNC migration compared to supernatants from control cultures, however not compared to the conventional limit of significance, MI = 0.80. With increasing PMNC migration there was an insignificant decrease in the MI. Addition of LPS, 1 x 10(-9) g/ml, during LIF induction caused a significant increase in LIF production, an effect which overshadowed the effect of PPD. Thus, the application of the conventional limit of significance, MI = 0.80, may result in false-negative or false-positive conclusions, depending upon the endotoxin contamination. A standardization of the endotoxin content in both steps of the indirect leucocyte migration inhibition assay seems mandatory in order to obtain a reliable and reproducible bioassay.

Cytokines cause functional and structural damage to isolated islets of Langerhans

Cytokines are soluble, antigen non-specific, non-immunoglobulin mediators produced and secreted by blood mononuclear cells interacting in the cellular immune-response. To test the possibility that cytokines participate in the autoimmune destruction of the pancreatic beta-cells leading to insulin-dependent diabetes mellitus, isolated human or rat islets of Langerhans were incubated for 7 days with cytokine-rich, cell-free supernatants of blood mononuclear cells from healthy human donors stimulated with or without purified protein derivative of tuberculin or phytohaemagglutinin. Glucose stimulated insulin-release, and contents of insulin and glucagon in islets incubated with cytokine-rich supernatants were markedly reduced. This impairment of islet function was due to a cytotoxic effect of cytokine-rich supernatants as judged by disintegration of normal light-microscopic morphology.

Further evidence of the development of delayed-type autoimmunity against arterial vessel-wall antigens following acute hypertensive damage to arterial vessels in rats

Acute hypertensive damage to arterial vessels was induced by intravenous injections of hypertension. The in vitro immunological method of the agarose migration technique was used for demonstration of delayed-type autoimmunity against arterial vessel-wall antigens following the damage of the arterial vessels. By means of this technique it was demonstrated that the migration indices from the rats with induced hypertension differed significantly from the control rats, P less than 0.005. This means that an autoimmunity of the delayed type had developed after the hypertensive damage to the arterial vessels. The autoimmunity was tissue specific.

Interleukin-1-like activities in synovial fluids of patients with rheumatoid arthritis and traumatic synovitis

Interleukin-1 (Il-1)-like activity in biological fluids was measured by their ability to rectify the Il-1-dependent lymphokine production of highly purified T lymphocytes to a recall antigen. Il-1-like activity was found in 9 of 11 synovial fluid (SF) specimens from patients with rheumatoid arthritis (RA) but only in 2 of 11 paired RA sera. In traumatic synovitis, low Il-1-like activity was recorded in 5 of 9 SF specimens, and a similar low activity was found in sera of 4 of these patients. The Il-1-like activity was partly absorbed by an anti-Il-1 antibody. The presence of Il-1 in the SF of patients with RA suggests in vivo activation of monocytes/macrophages.

Lack of evidence for human lymphokines with thrombocyte aggregating activity. An in vitro study

The ability of human lymphocytes to produce soluble mediator(s) with thrombocyte aggregating activity (TAA) was investigated in an in vitro technique. Isolated human mononuclear cells were stimulated with phytohaemagglutinin or purified protein derivative of tuberculin. The supernatants were investigated for lymphokine activity in a leucocyte migration inhibitory factor assay. Supernatants were then tested for their ability to aggregate human thrombocytes, and in contrast to the results of previous studies, we were not able to demonstrate any TAA. Most likely, lymphokines with TAA are not involved in the thrombotic processes seen in human cell-mediated immune inflammatory reactions.

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.

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.

Radiosensitive suppressor T cells for LIF production in mixed lymphocyte reactions

LIF activity in the supernatants of one way MLR, one MNC population being irradiated, was significantly increased as compared to that produced in two way MLR. Puromycin treatment of the irradiated cells decreased LIF response while puromycin treatment of the non-irradiated cells had no detectable effect. A similar increase of LIF activity was achieved by removing either OKT8+ or OKT4+ cells from one cell component before performing the mixed culture. Recombination of the depleted cell samples followed by MLR decreased LIF response except when belonging to allogeneic donors. Mostly, irradiation of OKT8 depleted mononuclear cells before recombination with OKT4 depleted cells prevented LIF suppression in MLR. The suppressor function of OKT4+ cells seems to be more radiosensitive than that of OKT8+ cells in this system. It is suggested that LIF production in MLR is regulated by a suppressor circuit which is histocompatible restricted and requires interaction of both OKT4+ and OKT8+ cells.

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.

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.

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.

Severe acquired immunodeficiency in European homosexual men

Four previously healthy Danish homosexual men developed Kaposi's sarcoma or opportunistic infections with fever of unknown origin and lymphadenopathy. One patient died of a Pneumocystis carinii pneumonia. Three patients had defective cell-mediated immunity with absent leucocyte interferon production and decreased proliferative response to mitogens and antigens. T lymphocyte helper subsets and natural killer cell activity were reduced. Unstimulated mononuclear cells produced leucocyte migration inhibitor factor. Two patients were sexual partners and three had never been to the USA, where cases of severe acquired immunodeficiency have been reported. Thus, the syndrome must also be suspected in European homosexual men who present with fever of unknown origin, opportunistic infections, or Kaposi's sarcoma.

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.

Role of Zn2+ and other divalent metal ions in human lymphokine production in vitro

The effects of phenanthroline and of various metal ions on human leucocyte migration inhibitory factor (LIF) production were studied. Previously reported preliminary data showed that phenanthroline, a divalent metal ion chelator, reduced the elaboration o LIF in a dose-dependent manner by specifically but not by non-specifically stimulated lymphocytes. This paper shows that suppression of LIF production caused by phenanthroline could be entirely reversed by Zn2+, Ni2+ and, most effectively, by Co2+. When a battery of divalent cations were tested for direct inhibitory effects on LIF production, Cd2+ and, to a lesser extent, Cu2+ were found to be effective. Again, only specifically stimulated cells were susceptible. This profile of responses resembles greatly that seen in experiments with carboxypeptidases, indicating that a carboxypeptidase-like, probably Zn2+-dependent enzyme is active during antigen-induced lymphokine production. This metalloenzyme may be derived from activated monocytes/macrophages and, like the lymphocyte-activating factor, exerts its activity in the G1 phase of the cell cycle.

Induction of antigen-specific immunological unresponsiveness by inhibitors of human lymphocyte-activating factor

Antigen-stimulated blood mononuclear cells preincubated in vitro with Cd2+ or phenanthroline, a Zn2+-chelator, did not respond normally on restimulation with antigen, as judged by their ability to elaborate leucocyte migration inhibitory factor (LIF). Other divalent metal ions, including Zn2+, were ineffective. The effect was immunologically specific, since challenge of similarly pretreated cells with an unrelated antigen, to which the cells were also sensitized, resulted in normal LIF production. The lack of responsiveness could not be ascribed to cell death, carry-over of the inhibitors, or exhaustive release of LIF during the inductive phase. Phenanthroline and Cd2+ are known to inhibit the activity of the macrophage-derived lymphocyte-activating factor (LAF), whose effect is exerted non-specifically on antigen-stimulated lymphocytes in G1. Seen in the context of a two-signal model of lymphocyte activation, it is hypothesized that immediate tolerance induction is triggered by delivery of the antigenic stimulus (signal 1) without addition of the non-specific signal 2 (LAF).

Modulation by adherent cells and irradiation of in vitro LIF production by Con-A stimulated mononuclear cells

LIF activity production by ConA-stimulated mononuclear cells was tested by measuring granulocyte migration from clotted plasma droplets placed in Microtest II plates. 90 min. incubation of MNC cultures with ConA assured a significant LIF activity in the 24 h. culture supernatants. Removal of the adherent cells after ConA pulse exposure improved (p less than 0.05) LIF production. Enrichment with adherent cells of MNC cultures before ConA stimulation decreased LIF release. Irradiation (600 rad) of ConA stimulated MNC cultures, however, abrogated both phenomena induced by either removal or enrichment of the adherent cells. Indomethacin, when added during ConA pulse exposure to adherent cell rich MNC cultures, also increased LIF activity production. Both, PGE1 and supernatants of ConA-pulsed monocyte rich cultures had similar LIF impairing effects but the suppressive activity was abolished either by supernatants dialysis or by irradiation of stimulated MNC cultures.

Differential role of Zn2+ in antigen- and mitogen-induced lymphokine production

The effect on human lymphokine production in viro of phenanthroline, a Zn2+-chelating agent and an inhibitor of carboxypeptidases A and B, was tested. The elaboration of leucocyte migration inhibitory factor (LIF) by tuberculin-sensitized mononuclear cells stimulated with the specific antigen was reduced in a dose-dependent manner, an effect completely restored by addition of excess Zn2+. In contrast, phenanthroline did not affect LIF production by mononuclear cells activated nonspecifically by phytohaemagglutinin. It is hypothesized that the presence of a Zn2+-dependent molecule, possibly a carboxypeptidase, may be necessary for antigen- but not for mitogen-induced lymphokine production.