Lipopolysaccharide Stimulation of Plasmacytoma Cells

Various preparations of lipopolysaccharides (LPS) were tested for their effect on 6 plasma tumor cell lines. LPS from Escherichia coli B5:055, Salmonella minnesota 1114, and R7 mutant, as well as the glycolipid from S. minnesota 595 were highly stimulatory on cell suspensions from solid transplantable plasma tumor cells MOPC 315 and MPC11, as measured by thymidine incorporation and cell proliferation. Even nanogram doses were effective. LPS preparations from S. minnesota R5 and endotoxin-free cell wall residues of R5 and R7 mutants of S. minnesota had no stimulatory effect on these cells. In contrast, 4 lines of tissue culture-adapted plasma tumor cells (Adj PC5, HOPC-1, MOPC-21, and MPC11 TC) were not affected by any LPS preparation tested. Lymphosarcoma P1798 cells were also unaffected by these LPS.