Lipopolysaccharide and pristane-induced peritoneal exudate requirements for plasma tumor cell colony formation.

The role for lipopolysaccharide (LPS) and a pristane-induced peritoneal exudate (PIPE) on the in vitro development of murine plasmacytoma was studied. MOPC-315 cell suspensions showed little tendency for colony formation in a soft agar culture medium. Additions of LPS and PIPE were required for maximal colony formation. The LPS effect was dose-dependent down to nanogram quantities. PIPE prepared from inbred strains of mice not susceptible to pristane-induced plasmacytoma (DBA/2) or from normal peritoneal washings was ineffective. PIPE activity was radioresistant and not transferable by cell-free conditioned medium. Three strains of transplantable plasmacytomas showed colony formation stimulation by LPS plus PIPE, but LPS and PIPE were ineffective with lymphosarcoma P1798.