The Role of T Lymphocytes in the Primary Humoral Antibody Response to Brucellin

Abstract

The relative ability of normal and adult, thymectomized, bone marrow-reconstituted (TxIB) CBA/J mice to produce humoral antibody in response to primary brucellin immunization was assessed over a wide antigen dose range. An analysis was made of the kinetics and immunoglobulin class of the primary humoral antibody response in relation to the immunizing dose of brucellin employed. Antibody responses in T cell deficient (TxIB) mice were characterized by an increase in the threshold dose of brucellin at which antibody production was initially detected, by a prolongation of the latent period before the onset of antibody production, by a delay in the switchover from mercaptoethanol-sensitive (MES) to mercaptoethanol-resistant (MER) antibody production, and by a decrease in the peak titers of MES and MER antibody achieved. At low brucellin dose levels, the MES antibody responses were chiefly depressed; at intermediate dose levels, both the MES and MER antibody responses were depressed; at high brucellin dose levels the MER antibody responses alone were depressed. The nature and degree of suppression of antibody production observed in TxIB mice for a given immunizing dose level of brucellin was equivalent to the suppression obtained through the use of 100- to 1000-fold lower immunizing dose levels of brucellin in normal mice.