Lymphoblastogenesis inhibitory factor produced by human lung cancer cell lines

A comparative study of the inhibitory effect of cell-free supernatants (CFS) from human lung cancer cell lines (ChaGo and PC-1) and from a human embryo fibroblast cell line on lymphocyte blastogenesis indicated that both lung cancer cell lines produce a large amount of the inhibitory factor while the production of such a factor from a control noncancer cell line is essentially very minimal or absent. The inhibitory effect of CFS of the lung cancer cell lines is not due to direct cytotoxicity. The inhibitory effect is found to be partially sensitive to heat treatment. A significant inhibition is still seen, even when the CFS of the lung cancer cell lines were present for 1 hour prior to the addition of phytohemagglutinin (PHA).