The influence of adjuvants on the immunological response of the chicken. II. Effects of Freund's complete adjuvant on later antibody production after a single injection of immunogen.

A study has been made in the chicken of the late phase (after the 21st day) of the immunological response to a single intramuscular injection of a soluble protein antigen, human serum albumin (HSA), incorporated in a water-in-oil emulsion with or without heat-killed Mycobacterium tuberculosis. Birds injected with a water-in-oil emulsion showed, after a fall from the initial primary response peak (8–12th day), a second rise in antibody production beginning at the 21st day. Control birds injected with HSA in 0.15 M NaCl failed to show this second rise. The peak of the second phase of antibody production in these experiments fell between the 42nd and 59th days. The results of one experiment showed that in birds injected with Freund's complete adjuvant the average second peak level was 100-fold higher than the average first peak level. However, the second peak level of antibody reached was much higher in birds injected with HSA in Freund's complete adjuvant than in those injected with a simple water-in-oil emulsion. The avidity of anti-HSA present in the second phase of antibody production by birds injected with HSA in water-in-oil emulsions has been compared with the avidity of anti-HSA produced during the first phase (10th day). The avidity of sera obtained during the second phase of anti-HSA production by birds given water-in-oil emulsions with or without added M. tuberculosis was much greater than that of sera obtained during the first phase. The anatomical site of antibody production during the second phase of antibody production has been investigated. The findings suggest that, whereas antibody production during the first phase is in the spleen and probably other lymphoid tissues, much of the antibody produced during the second phase may be from the granuloma produced at the site of injection of the water-in-oil emulsion.