Modulation of the immune response by proopiomelanocortin derived peptides. II. Influence of adrenocorticotropic hormone on the rise in intracellular free calcium concentration after T cell activation.

In this paper the effect of ACTH 1-24 is described on one of the "early events" occurring during T cell activation: the rise in the concentration of cytosolic free calcium. The increase in cytosolic free calcium induced by concanavalin A or by a monoclonal antibody with specificity for the T cell receptor-T3 complex could be modulated by physiological concentrations of ACTH 1-24. The modulation of the response appeared to be dose dependent. The effect of ACTH 1-24 was maximal at 10(-10) M. No effect of ACTH 1-24 was observed on the basal level of cytosolic free calcium. These results indicate that physiological doses of ACTH can interfere with the responsiveness of T cells to mitogenic and antigenic stimuli.