How arachidonic acid depresses thymus weight.

Subcutaneous injection of arachidonic acid depresses thymus weight. This is unlikely to be a stress effect, since arachidonic acid is equally active in adrenalectomised animals. Amongst other fatty acids tested, those capable of being metabolised to arachidonic acid have greater thymolytic activity than those which are not arachidonic acid precursors. Thymolysis is significantly inhibited by indomethacin, a drug which blocks the conversion of arachidonic acid to prostaglandins.