Variations in the properties of rabbit antibodies during prolonged immunization by various routes with serum albumin in Freund's complete adjuvant.

Alterations in the functional properties of antibodies formed during prolonged immunization with bovine serum albumin and Freund's complete adjuvant were indicated by the synthesis of non-precipitating antibody and by the increased avidity of the antibody formed during the course of immunization. Prolonged antigenic stimulation often resulted in decrease in both the level and precipitating efficiency of antibody. The route of immunization did not affect the quality (i.e. avidity, precipitating efficiency) of the antibody produced but did affect the quantity of antibody formed, as indicated by assay of antigen binding or precipitation. Passive haemagglutination tests failed to disclose significant differences in the response of individual rabbits. Although repeated, multiple subcutaneous injections or several, single subcutaneous injections in the intranuchal area resulted in somewhat less antibody than footpad immunization, the greater ease of injection and the less severe granuloma formation indicated that the latter routes were preferable.