LYMPHOCYTE ENDOTHELIAL INTERACTIONS IN INFLAMED SYNOVIA - INVOLVEMENTOF SEVERAL ADHESION MOLECULES AND INTEGRIN EPITOPES

The role of several adhesion molecules for lymphocyte-endothelial inte ractions in the synovia of rheumatoid arthritis patients was studied u sing the frozen section assay. Partial inhibition of lymphocyte bindin g to endothelium of synovial sections could be observed with antibodie s against CD44, L-selectin, and beta1- and beta2-integrins, pointing t o the participation of several adhesion molecules in the regulation of lymphocyte immigration into inflamed synovia rather than the presence of a unique homing receptor. Different degrees of inhibition were fou nd within a series of antibodies against alpha4- and beta1-integrins k nown to have functional effects in other interaction systems. In addit ion, increased binding to endothelial cells was induced when lymphocyt es were pretreated with TS2/16 anti-beta1 IgG, whereas binding to non- endothelial components of synovia was increased after treatment with H P 2/4 (anti-alpha4) Fab. The data suggest a multifunctional role Of al pha4/beta1-integrins in directly mediating adhesion as well as regulat ing adhesive interactions in the rheumatoid synovia.