ENGAGEMENT OF MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-II MOLECULES INDUCES SUSTAINED, LYMPHOCYTE FUNCTION-ASSOCIATED MOLECULE-1-DEPENDENT CELL-ADHESION

Antigenic stimulation is associated with enhanced adhesion between T cells and antigen-presenting cells (APC). Binding of ligands to the T cell antigen receptor activates the adhesion function of lymphocyte function-associated molecule 1 (LFA1; CD11a/CD18). We demonstrate here that ligand binding to major histocompatibility complex class II (Ia) molecules also activates LFA-1 function, providing a reciprocal mechanism for the induction of adhesion between T cells and Ia+ APC. Adhesion was affected by a qualitative change in LFA1 molecules and was reversed by the protein kinase C inhibitor sphingosine. These results define a novel role for la molecules as signal transducing receptors that regulate LFA1-dependent adhesion via a putative, Ia-coupled protein kinase(s). © 1990, Rockefeller University Press., All rights reserved.