Adhesion Molecules Involved in Protein Kinase A- and C-Dependent Lymphocyte Adherence to Microvascular Endothelial Cells

A twofold increase in lymphocyte adherence to rat microvascular endothelial cells (EC) was achieved by incubating EC for 4 h with IL-1α or dibulyryl-cAMP (stimulators of protein kinase A, PKA) and PMA (stimulator of protein kinase C, PKC). Monoclonal antibodies anti-CD11a, anti-CD18 (LFA-I) and anti-CD49d (VLA-4α) significantly inhibited the increased lymphocyte binding to IL-lα-induced EC, anti-CD 18 and to a lesser extent anti-CD11a and anti-CD49d to dibutyryl-cAMP-induced EC, whereas only anti-CD11a and anti-CD18 monoclonal antibodies inhibited PMA-induced lymphocyte binding. These findings suggest that stimulation of PK A and PKC induces lymphocyte binding to EC via different adhesion molecules.