BETA-1-INTEGRIN-MEDIATED LYMPHOCYTE ADHERENCE TO EXTRACELLULAR-MATRIX IS ENHANCED BY PHORBOL ESTER TREATMENT

The interaction of the human T cell leukemia, Jurkat, with the extracellular matrix components collagen and fibronectin was examined. These cells displayed constitutive binding to fibronectin and low levels of adherence to collagen which were enhanced following stimulation with phorbol esters. The relevant binding structures were identified as members of the CD29/beta-1 integrin family of adhesion molecules. Adherence to collagen and to fibronectin was mediated by alpha-2-beta-1 and alpha-5-beta-1, respectively. The enhancement of adherence by phorbol esters did not involve up-regulation of receptor expression but appeared to derive from the increased functionality of structures which were expressed on the cell surface.