The involvement of cAMP in lymphocyte capping

We have observed that agents that are known to elevate intracellular levels of cAMP such as N⁶,O²-dibutyryl adenosine 3′,5′-cyclic monophosphoric acid (dbcAMP) and theophylline cause a remarkable stimulatory effect on the lymphocyte receptor mobility phenomenon. Increased intracellular concentration of cAMP enhances not only antibody-induced but also Con A-induced lymphocyte capping events in T-lymphoma cells. In addition, we have noted that N²,O²-dibutyryl guanosine 3′,5′-cyclic monophosphoric acid (dbcGMP) does not stimulate but actually slightly inhibits the receptor movement. Furthermore, we have determined cAMP levels to increase greater than twofold during ligand-induced capping using a radioimmunoassay. Therefore, our data strongly suggest that cyclic adenylic monophosphoric acid (and not cGMP) is specifically involved in the redistribution of lymphocyte membrane proteins induced by both antibody and Con A.