Hyporesponsiveness to virus antigens in rheumatoid synovial and blood lymphocytes using the indirect leucocyte migration inhibition test

Etiology of rheumatoid arthritis

Definite genetic associations with immunological cooperative HLA-D(R) antigens have been demonstrated for rheumatoid arthritis (RA). Microbial etiology has not been proven, but some hope for the supporters of this view is still given by small viruses, plasmids of enteric bacteria or perhaps oncogen-like DNA-sequences. Yet, electrophoretical analysis of membrane proteins or surface glycoproteins of RA synovial cells does not show any differences compared to reference cells. Autoimmunity to several tissue elements has been demonstrated, but most of it is of secondary nature. Antigenicities of type II and III collagens are probably only contributory factors for HLA-DR4 positive individuals. Proteoglycans or minor cartilage collagens have not been extensively studied, so far. Endocrine, dietary or psychological influences might be triggering events for otherwise 'preloaded' individuals.

No demonstrable association between HLA DR4 and in vitro collagen reactivity as determined by the production of leukocyte inhibition factor

Eight HLA DR4 positive and 9 HLA DR4 negative healthy volunteers as well as 2 DR4 positive and 1 DR4 negative patients with rheumatoid arthritis (RA) were compared for leukocyte inhibition factor (LIF) production and lymphocyte proliferation in response to native and denatured collagen types II and I/III. Purified protein derivative (PPD) of tuberculin served as a positive control in the LIF assay and PPD and phytohaemagglutinin (PHA) in the lymphocyte proliferation test. No significant difference in responsiveness to collagen was detected between these two HLA groups. The reactivity to collagen was not affected by removal of OKT8+ lymphocytes. The present results are in conflict with earlier reports by Solinger et al. (1981) and Solinger & Stobo (1982). The reason for the discrepancy has not been resolved.

Natural killer (NK) cell activity of peripheral blood, synovial fluid, and synovial tissue lymphocytes from patients with rheumatoid arthritis and juvenile rheumatoid arthritis

Natural killer (NK) cell activity was investigated in peripheral blood, synovial fluid, and synovial tissue lymphocytes from patients with rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA). Unfractionated lymphocytes, T lymphocytes, and non-T lymphocytes from the 3 compartments of JRA patients had reduced activity compared with that of normal peripheral blood lymphocytes (with p values usually between 0.05 and 0.1). Unfractionated synovial tissue lymphocytes of RA patients also showed reduced cytotoxicity (0.05 less than p less than 0.1), whereas peripheral blood lymphocytes exerted normal NK cell activity. The NK activity was exerted by cells both with and without Fc gamma receptors. The highest cytotoxicity was observed in Fc gamma receptor-positive cells, both in peripheral blood and synovial fluid, since more than 70% reduction in NK activity was found after depletion of Fc gamma receptor-positive cells. No evidence of lymphocytotoxic antibodies or other factors with influence on NK cells was observed in the patients' sera.

Inflammatory synovial tissue mononuclear cells release leucocyte migration inhibition factor in antigen- and mitogen-free cultures

The presence of leucocyte migration inhibition factor (LIF) in supernatants from apparently antigen- and mitogen-free cultures of mononuclear cells (MNC) was studied. MNC were eluted from inflamed synovial tissue or isolated from blood. Untreated supernatants, supernatants in which any LIF had been inactivated, and culture medium were compared in their ability to affect the migration of homologous polymorphonuclear leucocytes. LIF was released by synovial tissue MNC from all of the 9 patients studied, consisting of 5 patients with rheumatoid arthritis, 2 with psoriatic arthropathy, and 2 with juvenile rheumatoid arthritis. Blood MNC of the patients and of 8 healthy blood donors did not release LIF. When synovial tissue MNC supernatants from 2 patients were examined, LIF activity increased as time of incubation was extended. In at least 2 synovial tissue MNC supernatants in which LIF had been inactivated a migration enhancement activity was revealed.

Spontaneous release of leucocyte migration-inhibitory factor by mononuclear cells eluted from rheumatoid synovial tissue

Spontaneous leucocyte migration-inhibitory factor (LIF) was assayed by an indirect system in which mononuclear cells (MNC) eluted from rheumatoid synovial tissues or isolated from peripheral blood of normal donors were cultured without antigen. The supernatants from these cultures and control supernatants, heated to 80 degrees C for 30 min to destroy the LIF activity, were used in the test. In seven out of eleven rheumatoid arthritis patients the eluted synovial MNC produced LIF spontaneously, whereas none of the twelve normal blood donors showed any such production. The ability to show spontaneous LIF production was primarily seen in the joint tissues from sero-negative patients.