ADHESION OF RHEUMATOID LYMPHOCYTES TO MUCOSAL ENDOTHELIUM - THE GUT REVISITED

By a study of the adhesion of rheumatoid mononuclear cells, we have so ught to clarify the homing properties and origins of cells likely to b e involved in the pathogenesis of this disease. The adhesion of mononu clear cells from patients with rheumatoid arthritis (RA) was enumerate d by an in vitro adherence assay using frozen sections of endothelium- containing gut lamina propria (EGLP) from porcine small intestine. Pre liminary studies verified the involvement of known adhesion molecules by inhibition assays using monoclonal antibodies Meca-367, Mel-14 and Hermes-3. Twenty-five paired samples of peripheral blood (PB) and syno vial fluid (SF) were studied, plus six from synovial membrane (SM) and eight from patients with other diseases. There was a significantly gr eater degree of adherence to EGLP by SF cells than PB (mean adherence 266 +/- 22 cells/mm(2), compared to 136 +/- 13 cells/mm(2), respective ly, the majority of which were CD8+ cells; P = 0.02, Mann-Whitney U-te st for 25 paired samples). The results of the monoclonal antibody inhi bition assays were in keeping with the involvement of homing receptors to gut endothelium in our assay system. Synovial fluid lymphocytes fr om RA patients exhibited adhesion properties more in keeping with lymp hocytes of mucosal than of lymph node origin. Synovial membrane lympho cytes, by contrast, showed poor adherence to endothelium-containing la mina propria. The gut, as an immune lymphoid organ, may thus play a co ntributory role in this disease, possibly through the pathological see ding of cells into the synovial space.