The Effect of Antigen Competition on Both the Primary and Secondary Immune Capacity in Mice

Abstract

Abstract The primary and secondary immune capacity in mice was studied during antigen competition. Three antigens were used: sheep erythrocytes (SRBC), rat erythrocytes (RRBC), and human γ globulin (HGG). The results of these studies demonstrate the following. 1) In both competition systems, SRBC prior to RRBC or HGG, a marked suppression of the secondary immune capacity corresponds to a suppressed primary agglutinin response to the second antigen. 2) The degree of suppression of the secondary agglutinin capacity can be reduced by increasing the dose of the secondary challenge, which suggests that in the secondary immune response there may be participation of both reacting sensitized and uncommitted immunocompetent cells. 3) The entire level of the immune suppression during competition is dependent upon the dose of the first antigen. Further, the experimental results do not support the possibility that the competition can be attributed to either an increased or a decreased rate of antigen elimination. 4) Antigen competition cannot be attributed to a deficiency in the extracellular localization of antigen in reticular cells of splenic germinal centers. 5) The deficiency in a competition system is attributed to an impairment which ultimately affects the immunocompetent cell or unit. One reflection of this lesion on the antigen-sensitive unit is expressed in the competition between SRBC and HGG. A detectable increase in the latent phase of the primary HGG agglutinin response occurs when the HGG is injected at 1 or 3 days after SRBC. The recruitment of immunocompetent cells, and thus priming, is limited by the decreased level of preexisting tissue-associated and/or free antigen. On the other hand, in a condidition where there was limited immune progenitor cell recruitment to RRBC as a result of subsequent competition with SRBC the result was antigen-driven depletion of the existing sensitized immune cell compartment.