Role of IgG(T) and IgGa isotypes obtained from arachnidic antivenom to neutralize toxic activities of Loxosceles gaucho, Phoneutria nigriventer and Tityus serrulatus venoms

Abstract The ability of IgG(T) and IgGa subclasses—isolated by liquid chromatography from equine arachnidic antivenom(AAV)—to neutralizetoxic activities of Loxoscelesgaucho , Phoneutria nigriventerand Tityus serrulatus venomsas well as to remove venomtoxins from circulation was investigated. These subclassesshowed similar antibody titers against L. gaucho , P. nigriventer and T. serrulatus venoms, and by immunoblotting few differences were observed in the recognition pattern of venomantigens. IgG(T) and IgGa neutralized100% lethality induced by L. gaucho and 50% of P. nigriventer venom, but IgGa failed to neutralizeT. serrulatus venom, in contrast to IgG(T). Both subclasses neutralizedlocal reactions and dermonecrosis induced by L. gaucho venomin rabbits. In mice, IgG(T) and IgGa partially neutralizedthe edematogenic activity induced by P. nigriventer and T. serrulatus venoms, but only IgG(T) neutralized(ca. 81%) the nociceptiveactivity induced by T. serrulatus venom. Both subclassesfailed to neutralize nociceptiveactivity induced by P. nigriventer venom. IgG(T) reduced the serum venomlevels of animals injected with L. gaucho , P. nigriventer or T. serrulatus venoms, while IgGa solely reduced L. gaucho and P. nigriventer venomslevels. Our results demostrate that IgG(T) and IgGa subclasses neutralizetoxic activities induced by P. nigriventer , T. serrulatus and L. gaucho venomswith different efficacies, as well as depuratethese venomsfrom circulation.