Effect of essential fatty acid deficiency on experimental allergic encephalomyelitis in rats.

Previous claims that experimental allergic encephalomyelitis (EAE) was enhanced by essential fatty acid (EFA) deficiency were reinvestigated. Deficiency was induced in Lewis rats by feeding a fat-free diet starting in late gestation, at weaning or in adult life with or without a previous period of starvation. Retardation of growth, the typical dermatitis, increased water consumption and testicular atrophy gave evidence of EFA deficiency. Control rats were fed a complete diet or a fat-free diet supplemented with corn oil. EAE was induced in EFA-deficient and control rats by conventional active sensitization with neural antigen and adjuvants or by passive transfer of living lymphoid cells from sensitized nutritionally normal donors. Contrary to previous reports, EFA deficiency did not enhance EAE in any of seven experiments, and these results were supported by histological examinations. In fact, we found inhibition of clinical signs, but not histological lesions, when EFA deficiency was moderately advanced. This was accompanied by (and probably related to) thymic atrophy, possibly due to nonspecific stress. Also we found that EFA deficiency had no effect on a non-immunological model of brain inflammation that resembles EAE in the occurrence of lymphocytic infiltrates.