DIFFERENTIAL-EFFECTS OF TEMPERATURE AND EXOGENOUS FATTY-ACIDS ON MITOGEN-INDUCED PROLIFERATION IN CHANNEL CATFISH LYMPHOCYTE-T AND LYMPHOCYTE-B

1. 1. Exogenously supplied, BSA complexed, saturated and unsaturated fatty acids were compared for their effects on mitogen-induced DNA synthesis in channel catfish T and B lymphocytes. 2. 2. At "permissive" in vitro temperatures (27°C), high concentrations (≥ 240 μM) of all the fatty acids used were inhibitory. However, at lower concentrations (80-160 μM), differences were noted in the ability of some fatty acids to modulate mitogen responses. While palmitic acid (16:0) and linoleic acid (18:2) had little effect on LPS-induced B cell- or Con A-indueed T cell proliferation, stearic acid (18:0) suppressed while oleic acid (18:1) enhanced T cell responses only. 3. 3. Adding equimolar amounts of 18:0 and 18:1 obviated the effects of singularly added fatty acids on T cell mitogenesis. 4. 4. 18:1 was used to successfully "rescue" ~ 60% of the Con A-induced T cell proliferation normally inhibited at "nonpermissive" in vitro temperatures (17°C). 5. 5. While B cells readily appear to desaturate 18:0 and synthesize unsaturated fatty acids, T cells accumulate comparatively large amounts of 18:0 in membrane associated phospholipids. 6. 6. It is proposed that 18:1 enhances T cell responses at permissive high temperatures and rescues suppressed T cell responses at nonpermissive low temperatures by increasing membrane fluidity. © 1990.