Separation and characterization of anti-benzylpenicilloyl (BPO) antibodies. II. Immunological properties of different IgG fractions.

Affinity chromatography and subsequent ion-exchange chromatography of pooled anti-benzylpenicilloyl (anti-BPO) hyperimmune sera separated 5 different anti-BPO IgG fractions as described in the preceding paper. These fractions were tested for activities in passive hemagglutination (PHA), passive immune hemolysis (PIH), antibody-dependent cellular cytotoxicity (ADCC) and influence on IgM-induced hemolysis. It was found that anti-BPO IgG fractions with low avidity (dissociation constant K = 4.4--6.7 X 10(-8) moles/l) were poorly active in PHA and ADCC and had no blocking activity in IgM hemolysis. Among the highly avid antibodies (K = 0.7--3.4 X 10(-8) mole/l) no correlations were found between avidity and activities in the immunological tests. The results presented demonstrate that ion-exchange chromatography allows the separation of blocking and lytic antibodies as shown by their influence on IgM-induced complement-dependent lysis of lightly hapten-coated sheep erythrocytes.