Effect of bovine non-agglutinating antibodies on the blood clearance of 131I-labelled Brucella abortus strain 45/20.

Non-agglutinating anti-Brucella abortus S45/20 antibodies were isolated and purified from sera of immunized cattle by means of immunoadsorption and ion-exchange chromatography (DEAE-Sephadex A-50). They corresponded to the IgG1 isotype as shown by immunoelectrophoresis using monospecific anti-IgG1 and anti-bovine gamma globulin sera. These antibodies failed to agglutinate the antigen. They were detected by the anti-bovine gamma globulin test, showing higher titres than those of agglutinating antibodies during the whole period of the experiment. Blood clearance of 131I-S45/20 in mice, was slower in those groups which had received non-agglutinating antibodies than in the control group.