The effect of adherent peritoneal exudate cells (APECs) and their products on the RPC-5 plasmacytoma growth in vitro.

The ability of peritoneal exudate cells (PECs) and their adherent (APECs) and nonadherent (NAPECs) fractions to enhance RPC-5 plasmacytoma growth in vitro was studied. The capability of these cells to bind RPC-5 cells and influence of the binding on cytolysis tumor cells by activated with C. parvum macrophages was also determined. The effector cells were harvested from mice injected i.p. with pristane, thioglicollate medium or C. parvum or from intact mice. The effect of supernatants from the in vitro cultured PECs, APECs or NAPECs on growth RPC-5 cells were also tested. It was found that the RPC-5 plasmacytoma growth was enhanced only by cells obtained from mice treated with pristane, or by supernatants from cultured PECs and APECs derived from pristane treated mice. The adherent cells from pristane treated mice were able to bind tumor cells. The tumor cells preexposed to adherent cells from pristane stimulated mice were resistant to lysis by activated with C. parvum macrophages.