Long chain fatty acid utilization of T-cells from autoimmune MRL-lpr/lpr mice.

To test the hypothesis that T-cells which exhibit abnormal immunological behavior manifest derangements in the de novo synthesis of phospholipids, the utilization of [3H]palmitic acid in B220+ T-cells from autoimmune MRL-lpr/lpr mice was investigated. The rate of incorporation of [3H]palmitic acid into membrane phospholipids was markedly increased in intact B220+ T-cells compared to that in T-cells from immunologically normal mice. The activities of two key enzymes involved in the de novo synthesis of palmitoyl-phospholipids, acyl-coenzyme (CoA) ligase and acyl-CoA; sn-glycerol-3-phosphate acyl transferase, were significantly higher in homogenates from B220+ T-cell membranes compared with those in controls. Despite these findings, the molar concentration of individual palmitoyl glycerolipids was equivalent in the membranes of B220+ T-cells and control lymph node T-cells. The results indicate that T-cells from lupus mice exhibit complex defects in the biosynthesis and turnover of membrane phospholipids and suggest the possibility that these aberrations contribute to T-cell dysfunction in autoimmune diseases.