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CD16+ monocytes, identified as a minor population of monocytes in human peripheral blood, have been implicated in several inflammatory diseases, including rheumatoid arthritis (RA). Fractalkine (FKN, CX3CL1), a member of the CX3 C subfamily, is induced by pro-inflammatory cytokines, while a receptor for FKN, CX3CR1, is capable of mediating both leukocyte migration and firm adhesion. Here, we investigated the role of FKN and CX3CR1 in activation of CD16+ monocytes and their recruitment into synovial tissues in RA patients. High levels of soluble FKN were detected in the synovial fluid and sera of RA patients. Circulating CD16+ monocytes showed a higher level of CX3CR1 expression than CD16- monocytes in both RA patients and healthy subjects. High level expression of CX3CR1 was also seen in CD16+ monocytes localized to the lining layer in RA synovial tissue. In the in vitro culture experiments, IL-10 induced CX3CR1 expression on the surface of monocytes, and TNFalpha induced membrane-bound FKN as well as soluble FKN expression in synovial fibroblasts. Moreover, soluble FKN was capable of inducing IL-1beta and IL-6 by activated monocytes. These results suggest that FKN might preferentially mediate migration and recruitment of CD16+ monocytes, and might contribute to synovial tissue inflammation.

High levels of soluble CD30 (sCD30) were detected in the serum and synovial fluid of patients with rheumatoid arthritis (RA), indicating the involvement of CD30+ T cells in the pathogenesis. We investigated the induction of CD30 and its functions in CD4+T cells from patients with established RA (disease duration >_2 years). CD4+ T cells from both the peripheral blood (PB) and synovial tissue (ST) of RA patients expressed surface CD30 when stimulated with anti-CD3 antibody (Ab) and anti-CD28 Ab, but their CD30 induction was slower and weaker compared with PB CD4+ T cells of healthy controls (HC). Immunohistochemical analysis showed that only a small proportion of lymphocytes expressed CD30 in the ST (-1%). RA PB CD4+ T cells, after recovery from 6-day stimulation with anti-CD3 Ab and anti-CD28 Ab, showed in intracellular cytokine staining that CD30+ T cells could produce more interleukin-4 (IL-4) but less interferon-gamma. In the culture of RA PB CD4+ T Cells with anti-CD3 Ab and anti-CD28 Ab, blocking anti-CD30 Ab similarly inhibited the cell proliferation and activation of nuclear factor-kappaB on day 4 in RA and HC, but inhibited the apoptotic cell death on day 6 only in RA. These results indicate that despite high-level expression of sCD30, the anti-inflammatory activity of IL-4-producing CD30+ CD4+ T cells may be limited in the ST due to a poor induction of surface CD30 and a susceptibility to CD30-mediated cell death.

In the present communication the recent works done by the Rheumatism Research Group of Department of Orthopedic Surgery, Okayama University, are described. The principal findings may briefly be summarized as follows. 1. Pathohistological pictures of the synovial membrane are classified into six types. Among them, Fibrinoid type and Follicular-Fibrosis type are the representative ones of chronic rheumatoid arthritis. 2. For the evaluation of the systemic as well as the local activities in rheumatoid arthritis and for judging the therapeutic effect, some indices have been established. 3. Injection of steroid hormones into the local joints fails to give satisfactory results in advanced, chronic rheumatoid arthritis. In such instances the flushing of the joint with physiological saline solution is effective. 4. In the case of chronic rheumatoid arthritis where the inflammation of hand and phalangeal joints is marked, RA-test gives rapid and more intense reaction, and most of such cases are of Follicular-Fibrosis type. 5. When lymph follicles appearing in the synovial membrane are stained when methyl green pyronine, the arrangement of lymphoid cells and plasma cells becomes distinctly clear. By micro-autoradiographic observations it can be seen that ³H-thymindine injected into the joint cavity is mostly ingested by the lymphoid cells in lymph follicles. 6. In the observation by the fluorescent antibody method multinuclear leucocytes found in the joint fluid and in the peripheral blood react with 19S and 7S-gamma-globulins. 7. When the serum and the joint fluid of the patient with rheumatoid arthritis are fractionated, they separate into three peaks at 19S, 7S, and 4S. Both S. S. C. A.-test and L. F. T. tests reveal the peak at 19S. The serum of chronic hepatitis positive to RA-test and the serum of rheumatoid arthritis are found to react immunologically the same to anti-β2 M globulin sheep serum. 8. When the reticulo-endothelial system of rat is blocked by 900,000 molecules of poly-vinyl-pyrroridon, the ability of antibody production is diminished. 9. Chemical synovectomy of injecting osmic acid is effective to FibrinoidCoating type. Its action mechanism lies in the complete cleaning of the surface of synovial membrane. 10. By radiating synovectomy with 193Au a fairly good result can be expected. 198Au is ingested by those cells in the surface layer of the synovial membrane and also by histiocytes in the synovial membrane. When 5 mc of 198Au are injected into the knee joint, a marked necrosis of the synovial membrane occurs. When 198Au is added to the ascites cells of rabbit during the tissue culture, in the concentration of over 14 μC degeneration of these cells can be recognized. 11. From the examination results of prognosis on those 25 cases with 41 rheumatoid knee joints after surgical synovectomy, it is considered that this method is indicated for Follicular-Fibrosis type. Ones with rheumatoid knee joint of Fibrinoid-Coating type gold sol treatment should be resorted to. In the cases of hand joints, surgical synovectemy is to be recommended at a relatively early stage.