Effect of Tumor Cell Conditioned Media on Secretion of TNF-α by Macrophages

Abstract

Conditioned medium obtained from rat liver (M cells) induced a greater than 3 fold increase in the proliferation of rat bone marrow macrophages. Non-specific esterase staining of the proliferated cells gave a positive result. The conditioned media obtained from 8 other established cell lines and 2 primary human cell cultures were also examined for their effects on cultured macrophages. All of the conditioned media tested increased macrophage proliferation. In addition, the conditioned media were examined to determine whether they induced TNF-α production in macrophages. TNF-α was not detected in the culture medium of the macrophages in the absence of conditioned medium derived from other cell cultures, but TNF-α production could be induced by the addition of these conditioned media. Conditioned media obtained from the cells of different species or tumor cell lines were more effective in inducing TNF-α production than those obtained from rat cell lines or normal tissue cell lines.