Immunosuppression in murine malaria. IV. The secondary response to bovine serum albumin.

The anamnestic antibody response of CBA mice to bovine serum albumin was characterized by a rapid production of high-avidity antibody. After 3 weeks both the total amount of antibody and its avidity declined but still remained above those seen in the primary response for at least 6 weeks. The effects of acute Plasmodium berghei and Plasmodium yoelii yoelii infections upon the induction and the expression of this anamnestic response were studied. Mice infected with these malaria parasites responded poorly to primary immunization and the immunological memory generated was quantitatively subnormal. In addition, presence of the infection during a period between approximately the second and third weeks of the primary response prejudiced the development of high-avidity memory. Optimally primed mice, challenged during a subsequent acute infection, responded well initially, but were unable to maintain the secondary response at a normal level in terms of both quantity and avidity of the antibody. However, if challenge was delayed until after recovery from the infection, a normal secondary response ensued. Antibody concentrations in the sera of primed animals declined rapidly during infection. This was at least partly due to increased catabolism.