Antibody Formation in the Rat

Abstract

Summary The role of a) dose of antigen, b) the route of its injection, and c) presence or absence of the spleen in the primary and secondary agglutinin response of the rat have been studied using purified particulate flagella from Salmonella typhosa as antigen. Within the range studied, injection of larger quantities of antigen resulted in higher circulating agglutinin levels in both the primary and secondary response. However, the greatest relative secondary response was seen after injection of smaller antigen doses. This paradoxical effect was probably due to the presence of higher agglutinin levels at the time of secondary stimulation in those groups receiving the larger quantities of antigen. At higher antigen dose levels, the general pattern of agglutinin response was qualitatively similar but quantitatively different depending upon the route of antigen injection. Striking qualitative differences were noted with different routes of injection when the smallest amount of antigen was administered. Splenectomy resulted in a lower peak titer and a delay in attaining peak titer regardless of route of injection. Absence of the spleen appeared to have less effect on the secondary response than on the primary response. The effects of splenectomy, however, interacted with those due to dose of antigen and route of administration. These findings emphasize the complexity of factors influencing the antibody response of a single species of animal to a well defined antigen.