Mouse macrophage hybridomas secreting a cytotoxic factor and interleukin 1

Stable mouse macrophage hybridomas were produced by somatic cell fusion between proteose peptone-elicited peritoneal macrophages and NS-1 myeloma cells. Three cloned hybrid cell lines, designated as N/P-5-3, -6-2, and -7-1, exhibited typical macrophage-like morphology. Moreover, their macrophage characteristics were confirmed by the manifestation of intracellular nonspecific esterase, the detection of Mac-1 antigens and Fc-receptors on the cell surface, and the demonstration of phagocytic and antigen-presenting activities. Furthermore, these cell lines, stimulated with LPS, secreted considerable amounts of a cytotoxic factor and interleukin 1. Cultured cells of various tumor cell lines were sensitive to the cytotoxic factor, but normal thymocytes, spleen cells, and liver cells were not killed by the factor.