ADJUVANT EFFECT OF LOXOSCELES GAUCHO (SOUTH-AMERICAN BROWN SPIDER) VENOM

Injection of L. gaucho venom and antigens (ovalbumin, ovomucoid and bo vine gamma globulin) into rabbit skin induced an intense local inflamm atory lesion and resulted in a significant increase in the level of Ig G antibodies to the antigen in both the primary and secondary humoral immune response. The adjuvant activity of the venom was associated wit h its high mel. wt components, which are responsible for the inflammat ory lesion. Rabbits rendered unresponsive to the venom and injected wi th venom plus antigen presented a very mild local inflammatory reactio n and no increase in antibody formation. When venom and antigen were i njected simultaneously but at different skin sites no adjuvant effect was induced. However, when antigen was injected 4 hr after venom injec tion but at the same skin site a significant adjuvant effect was produ ced. Furthermore, when venom plus antigen was injected intradermally i nto mice, a species in which the venom does not cause an inflammatory skin lesion, no adjuvant effect was detected. It is suggested that the adjuvant effect of L. gaucho venom in rabbits is probably due to its ability to cause a local severe inflammatory reaction.