Dietary lipids alter fatty acid composition and PGE2 production in colonic lymphocytes

The immune system can influence the development and growth of tumors, including those of the colon. Most studies of immune function utilize immune cells from the blood. Colonic mucosa, however, contains independently functioning lymphocytes that may have significant impact on colon tumor formation. Dietary lipids are known to influence the development of colon tumors and the function of peripheral immune cells. This study was designed to determine dietary lipid effect colonic lymphocytes (CL). CL were isolated from rats fed a diet high in corn oil or menhaden oil and cultured for 72 hours in the presence of absence of mitogen stimulation. Fatty acid composition of CL was measured by gas chromatography. Prostaglandin E2 levels were measured in conditioned media by enzyme-linked immunosorbent assay. CL proliferation rates were determined by colorimetric assay and thymidine incorporation. Results showed that CL from rats fed a diet high in corn oil had greater membrane concentrations of linoleic and arachidonic acids and higher levels of prostaglandin E2 production than those from rats fed a menhaden oil diet. Mitogen stimulation did not increase CL proliferation. Antitumor effects of n-3 fatty acids in the colon may involve anti-inflammatory responses by colonic lymphocytes.