SNAKE ANTIVENOMS FROM HYPERIMMUNIZED HORSES - COMPARISON OF THE ANTIVENOM ACTIVITY AND BIOLOGICAL PROPERTIES OF THEIR WHOLE IGG AND F(AB')(2) FRAGMENTS

IgG and F(ab')(2) fragments were prepared from horse plasma rich in sp ecific antibodies against Brazilian Bothrops or Crotalus venoms. Both preparations, free of gross contamination with non-immunoglobulin prot eins, were able to combine in vitro with their respective antigens, fo rming immune complexes at antigen excess, equivalence or antibody exce ss, and activating the C system, through either the classical or the a lternative pathways. The IgG preparation was more effective in neutral izing the lethal factors in Bothrops or Crotalus venoms, compared with the F(ab')(2) fragments. In contrast, IgG and F(ab')(2) anti-Bothrops venom were almost equipotent in neutralizing the haemorrhagic and def ibrinating activities in the venom. The method used to purify IgG, pre cipitation of most non-immunoglobulin plasma proteins with caprylic ac id, produced antivenoms richer in specific antibodies, with higher spe cific activity, recovery and yield, compared with the method commonly used to prepare antivenoms containing F(ab')(2).