Nutrition and immunity: The immunoregulatory effect of n-6 essential fatty acids is mediated through prostaglandin E

Suppression of cell-mediated immune responses by essential fatty acids (EFA) was demonstrated in mice maintained on a standard laboratory diet for rodents. Daily oral administration of EFA at doses ranging from 125 to 750 mg/kg body weight significantly suppressed local host-versus-graft and graft-versus-host reactions as measured by popliteal lymph node assay. Studies employing immune sera directed against E-type prostaglandin demonstrated that n-6 EFA-induced suppression was mediated through prostaglandin E₁. In titration experiments the effect of n-6 EFA on the reactions was dose dependent with enhancement of the responses at low concentrations and suppression at high concentrations.