Abstract
The dynamics of circulating tetanus toxoid (TT) antigen reactive B and T cells were studied in two donors for a period of 14 days following booster immunization with TT. A limiting dilution analysis was used to assess the number of T cells that proliferate in response to antigen. Binding of radiolabeled antigen was used to assess the number of antigen reactive B cells. The frequencies of circulating TT reactive T and B cells dropped sharply 24–48 hr postimmunization and remained low for 24–48 hr then rose by 5 days postimmunization to twice and three times their preimmunization levels, respectively, and remained at this high level for the rest of the 14-day study period. In contrast, there was no change in the frequencies of T and B cells reactive to control antigens such as monilia and diphtheria antigen. Studies of the in vitro synthesis of IgG anti-TT revealed the presence in the circulation, from Days 5 to 11, of B cells that were spontaneously secreting IgG anti-TT. This transient burst of circulating activated B cells was followed by a sustained increase (through Day 14) in the capacity of the circulating B cells to synthesize IgG anti-TT in response to PWM stimulation. These studies indicate that a negative selection of TT reactive T and B cells occurs shortly after immunization with TT, possibly because of sequestration of these cells in lymphoid tissue. This is followed by a sustained increase in the number of circulating memory T and B cells and in the case of B cells by transient activation into the secretion of TT-specific antibody.
Published Version
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