Interaction of Gc (vitamin-D binding protein) with membrane of activated natural cytolytic cells.

Gc (a vitamin D binding protein) has been speculated to play a role in the function of immune response, yet, it has not been examined for its biological response properties. Therefore, we tried to (a) characterize the appearance of membrane bound Gc (mGc) on non-activated and mitogen activated lymphocytes as well as on Interleukin-2 activated killer cells and (b) examine the role of serum isolated human Gc on human blastogenesis and cytotoxicity (natural killing and lymphokine-activated killing). Our data suggests that activated cells possess a greater number of cells with mGc than non-activated cells and that as a biological response modified we find modulation of blastogenesis and cytotoxicity to be consistently but not very significantly down-regulated. Anti-Gc antibody was observed to significantly inhibit NK activity.