Studies of Opsonic Activity in Univalent 6.5S Rabbit Antibacterial Antibody

Further definition of the structural γG requirements for effective opsonic function was sought using rabbit univalent antibacterial hybrid γG antibody to several strains of Escherichia coli. Hybrids of immune and normal γG made at ratios of 1:4 and 1:10 showed complete loss of opsonic function while retaining their capacity to combine with bacteria as shown by Coombs'-type facilitation of bacterial agglutination reactions. Self-recombinants of immune γG retained some degree of opsonic activity. When hyperimmune rabbit antibody was reduced and alkylated alone with 0.02 M concentrations of mercaptoethanol, there was considerable loss of opsonic activity. These experiments further emphasize the structural integrity necessary in the Fc portion of γG for complete expression of opsonic function.