The relatioship between serum immunoglobulin levels and specific antibody production in cows.

Antibody responses were measured, by the Farr ammonium sulphate technique, to two unrelated antigens-human serum albumin and sperm whale myoglobin. Differences between cows in their mean responses to both antigens were highly significant (P less than 0.001) but there were no differences between Jerseys and Friesians. Preinoculation IgG1, IgG2 and IgM levels were correlated with subsequent specific antibody production. The most significant relationship was between total immunoglobulin (IgG1 plus IgG2 plus IgM) and specific antibody production (r=0.76, P less than 0.01). But there was a negative correlation between the total Ig levels and the relative avidities of the antibodies produced (r=-0.65). These data suggest that in antibody production there is a balance between quality and quantity; cows with normally high serum immunoglobulin concentrations generally produce more antibody in response to challenge but this increase only compensates for the relatively lower avidity of their antibody for the antigen.