Membrane events leading to interferon-gamma induction by antigens.

Mitogenic induction of interferon-gamma in human peripheral blood mononuclear cells (PBMC) is prevented by enzymatic cleavage of galactose residues on the cell membrane, and by calcium depletion, suggesting that oxidation of galactose on the membrane glycoproteins and activation of a calcium flux across the membrane are critical events for interferon-gamma induction in nonspecifically stimulated human PBMC. The same experimental design has been applied to human PBMC cultures enriched of specifically sensitized lymphocytes and stimulated with the respective antigens. The results of these experiments show that also antigenic induction of interferon-gamma by purified protein derivative, tetanus toxoid, and MLR requires integrity of galactose residues and calcium intake suggesting that alteration of membrane-bound galactose and activation of a calcium flow are critical triggering events for both specific and nonspecific lymphocyte activation.