Colon cancer bearing rats produce a lymphokine which induces macrophage migration inhibition (MIF) in vitro

We studied a series of 40 rats at various stages of colorectal carcinoma, as induced by N-methyl-N-nitro-Nitrosoguanidine. Lymphokine containing supernatants were obtained simultaneously from splenic and peripheral lymphocytes, after exposure to rat colon cancer antigen in vitro. The lymphokine was found capable of performing Macrophage Migration Inhibition (MIF) when obtained from rats with: carcinoma through serosa, carcinoma of submucosa, carcinoma of the mucosa and carcinoma in situ. All control rats were free of cancer and were MIF negative. The MIF response in this study was evaluated as a marker of chemically induced colorectal carcinoma in rats in order to better understand the lymphocyte response to tumor progression from atypia to adenocarcinoma of the colon.