EFFECT OF CROTALUS VENOM ON THE HUMORAL AND CELLULAR IMMUNE-RESPONSE

The effect of venom of South American rattlesnake Crotalus durissus te rrificus (cdt) on the humoral and cellular immune response was studied in BALB/c mice that were immunized with soluble antigens [human serum albumin (HSA) or chicken ovoalbumin (OVA)] or sensitized to DNFB 1 hr after venom injection. Pretreatment of the animals with cdt venom ind uced a significant reduction in the level of anti-OVA and anti-HSA IgG antibodies. The effect of crotoxin, a major neurotoxic component of c dt venom, its acidic non-toxic subunit (CA) and its basic phospholipas e A(2) subunit (CB) was also studied. The whole crotoxin molecule was as able as cdt venom to induce a significant decrease in the level of anti-OVA and anti-HSA IgG antibodies. However, the CA and CB subunits of crotoxin did not change the antibody level to either antigen, sugge sting that the suppressive effect of crotoxin requires the intact mole cule. Both cdt venom and the whole crotoxin molecule were able to indu ce a significant decrease in the level of anti-HSA IgG1 antibodies. Th e levels of other IgG isotypes and IgE were barely detectable and coul d not be estimated. In spite of their suppressive effect on the humora l immune response neither cdt venom nor crotoxin had any effect on the cellular immune response as estimated by contact sensitivity reaction to DNFB. It is suggested that cdt venom and its crotoxin component ha ve an inhibitory effect on the humoral but not on the cellular immune response. (C) 1997 Elsevier Science Ltd.