The calculation of plasma cell reaction and influence of antigen dose.

The injection of sheep red cells and capsular antigen of Pasteurella pestis leads to increase in the absolute and relative number of plasma cells in the draining lymph node and spleen. An equation is proposed which is compatible with the linear relationship which is observed between the logarithm of the antigen dose and the square root of the number of plasma cells. An index of homogeneity is derived from this equation which is related to the number of different antigenic determinants and different antigenic molecules in the immunogen. This index varied in the predicted way when mice were immunized with relatively pure and crude preparations of capsular antigen.