Rabbit antibovine serum albumin antisera were fractionated by zone electrophoresis on starch, zone ultracentrifugation in sucrose density gradients, and diethylaminoethyl-cellulose chromatography, and were assayed by the passive HA technique. Antisera had at least two antibodies: one associated with a fraction characterized as a γ-2 globulin with a sedimentation rate of 7.3S and low anionic binding (fraction I), and one associated with a fraction characterized as a γ-1 globulin (or ß-globulin) with a sedimentation rate of 20.4S and high anionic binding (fraction IV). The HA titers of fractions I and IV of early sera were approximately equal. On prolonged antigenic stimulation fraction IV agglutinin decreased in concentration and the relative concentration of fraction I agglutinin increased. Chromatographic analysis of hyper-immune sera yielded 2 additional HA fractions with intermediate anionic binding. These results indicated that rabbits synthesize anti-BSA antibodies similar to rabbit anti-cellular antibodies.
Rabbit anti-BSA precipitin migrated mainly as a γ-2 globulin and the agglutinin migrated with γ- and ß-globulins. The evidence suggested that the HA method might measure antibody not measured by the quantitative precipitin technique.
