CORRELATION BETWEEN LOW-TEMPERATURE IMMUNOSUPPRESSION AND THE ABSENCE OF UNSATURATED FATTY-ACID SYNTHESIS IN MURINE T-CELLS

1. Studies were performed to determine if the inability of murine T cells to provide primary helper function at low temperature (27-degrees-C) could be correlated with their inability to synthesize unsaturated fatty acids (UFAs). 2. In the absence of exogenous oleic acid (18:1), splenocytes responded to a T-dependent (TD) Ag (trinitrophenyl-keyhole limpet hemocyanin, TNP-KLH) at 37-degrees-C but not at 27-degrees-C. The addition of 150-mu-M 18:1 almost completely restored plaque-forming cell (PFC) responses to TNP-KLH at 27-degrees-C but markedly suppressed PFC responses to the TD Ag at 37-degrees-C. 3. During incubation at 27-degrees-C, B cells converted 3-to 5-fold more stearic acid (18:0) to 18:1 and showed a greater accumulation of monounsaturated phospholipid molecular species than did T cells. 4. Following incubation in the presence of a rescuing dose of 18:1 (150-mu-M), both B and T cells accumulated large amounts of dioleoyl PC. 5. It is proposed that the absence of 18:1 synthesis in T cells is responsible for the unique low temperature susceptibility of this lymphocyte population.