[Immunological response of mice to diphtheria toxoid]

Following the determination of immunological response in mice, by titration, 1.5 Lf diphtheria toxoid was found as an optimal plasma cell activator. Groups of mice were subcutaneously injected with 1.5 Lf diphteria toxoid and on 2, 3, 4, 6, 10, 15 and 25th days of injection mice were killed and their blood, spleen, thymus, lymph nodes and lungs preserved. Section from these specimens were stained by methyl-green, pyronine and toluidine. Lymphocytes, plasma cells, and mast cells were counted in 10-20 fields in each preparation. Mature plasma cell ratio was calculated against lymphocyte counts. Mature plasma cell and mast cell counts and ratios of test mice were found increased when compared with that of normal control mice. The difference in thymus, spleen and lungs was found to be insignificant, however it was significant, p less than 0.05 in lymph. nodes. Maximum cell counts were seen at ten days. The sera of the test mice were also examined for humoral antibodies with precipitation and Römer's skin test. on 2, 3, 4, 6 and 10th days no antitoxin could be demonstrated in the sera of the test mice in controls either. In the sera taken on 15 and 25th days antitoxin was detected.