ADHESION OF RHEUMATOID LYMPHOCYTES TO MUCOSAL ENDOTHELIUM: THE GUT REVISITED

By a study of the adhesion of rheumatoid mononuclear cells,we have sought to clarify the homing properties and originsof cells likely to be involved in the pathogenesis of this disease.The adhesion of mononuclear cells from patients with rheumatoidarthritis (RA) was enumerated by an in vitro adherence assayusing frozen sections of endothelium-containing gut lamina propria(EGLP) from porcine small intestine. Preliminary studies verifiedthe involvement of known adhesion molecules by inhibition assaysusing monoclonal antibodies Meca-367, Mel-14 and Hermes-3. Twenty-fivepaired samples of peripheral blood (PB) and synovial fluid (SF)were studied, plus six from synovial membrane (SM) and eightfrom patients with other diseases. There was a significantlygreater degree of adherence to EGLP by SF cells than PB (meanadherence 266 ± 22 cells/mm², compared to 136 ±13 cells/mm², respectively, the majority of which were CD8+cells; P = 0.02, Mann-Whitney U-test for 25 paired samples).The results of the monoclonal antibody inhibition assays werein keeping with the involvement of homing receptors to gut endotheliumin our assay system. Synovial fluid lymphocytes from RA patientsexhibited adhesion properties more in keeping with lymphocytesof mucosal than of lymph node origin. Synovial membrane lymphocytes,by contrast, showed poor adherence to endothelium-containinglamina propria. The gut, as an immune lymphoid organ, may thusplay a contributory role in this disease, possibly through thepathological seeding of cells into the synovial space. KEY WORDS: Rheumatoid arthritis, Adhesion, MALT