The requirement for biotin and fatty acids in the cytotoxic T-cell response

Abstract

Dialyzed fetal calf serum (FCS) was a poor source of serum supplement for in vitro cytotoxic T lymphocyte (CTL) generation. Serum dialysate or biotin fully restored dialyzed FCS to activities comparable to FCS. It was concluded that the active principal in serum dialysate was biotin because its further dialysis was prevented by addition of avidin, a biotin binding protein. Avidin inhibited CTL generation only when added during the early stages of mixed lymphocyte cultures, whereas biotin could restore activity even if added at a later time. When FCS enriched in a fatty acid mixture, or in palmitic acid alone, was used as the serum supplement, avidin-mediated inhibition of CTL generation was markedly reduced. Avidin also inhibited CTL generation in cultures containing killed macrophages as the stimulating cell, and supplemented with Con-A-induced spleen cell supernatant, a source of helper factor(s). These experiments suggest that fatty acid biosynthesis and the attendant synthesis of structural lipids of appropriate fatty acid composition play a prominent role in the generation of CTL