Enhancement of macrophage survival and complement production by factors from cloned T cells

The addition of supernatants of some cloned mouse T cell lines to guinea pig peritoneal cells in tissue culture increased the production of the second (C2) and fourth (C4) components of complement as well as the enzyme beta-glucuronidase. Enumeration of cell populations demonstrated a simultaneous increase in cell survival. Supernatants that augmented functions of the cultured cells were obtained after alloantigen stimulation of a T cell line of C57BL/6 origin termed L2, but supernatants from a variant cell line derived from L2 and termed L2V had no effect. A delay of as little as 24 h in the addition of L2 T cell factors at the start of the cultures markedly diminished the effects on the cultured cells that were ordinarily observed 1-2 weeks later. These experiments suggest that, in this xenogenic system, complement-enhancing activity is part of a general stimulation of macrophages by cloned T cell factors.