The effects of lipopolysaccharide, BCG-immune T lymphocytes, and lymphokines on generations of tumoricidal pulmonary macrophages in Syrian hamster

Bacterial lipopolysaccharide (LPS) stimulates pulmonary macrophages from BCG immune-rechallenged hamsters to kill tumor cells in vitro. However, pulmonary macrophages from BCG immune and from untreated hamsters cannot be activated for tumor cytotoxicity by in vitro treatment with LPS. Pulmonary macrophages from the nonimmune hamsters acquire tumoricidal capacity after 3 hr of coculture with T cells from BCG immune-rechallenged hamsters or when incubated with Con-A-stimulated spleen cell supernatant fluid. A heterogeneous population of pulmonary lavage cells from BCG immune and from BCG immune-rechallenged hamsters destroys the tumor cells more effectively than a homogeneous population of pulmonary macrophages from the same animals. LPS significantly augments the cytotoxic activity of the heterogeneous population of pulmonary lavage cells.