Initiation of the Primary Immune Response to Sheep Red Blood Cells in Dissociated Mouse Spleen Cell Culture

I. Conditions for the Culture and Comparison of In Vitro Responses with In Vivo Responses

Abstract

Successful in vitro primary antibody formation to sheep red blood cells (SRBC) was obtained with normal mouse spleen cell suspensions cultured in the stationary state and in an atmosphere of 10% CO₂ in air. The response was measured by an increase in the number of hemolytic plaque forming cells and it reached about 30-150 per 10⁶ recovered cells by the 4th day of culture. The immunological activity of the spleen cell suspension was highly dependent on the cell-concentration of the suspension used for the culture, antigen dose to be added, the lot of calf serum employed in the culture medium and so on. The data obtained by the present in vitro studies on antigen dose, kinetics, and immunologic specificity indicated close similarities between the in vitro and in vivo response. Addition of "late" anti-SRBC serum, which contained mainly 7 S anti-SRBC antibody, to the cultures suppressed extremely the immune response in vitro, and the data on the suppressive effect of specific antibody are also consistent with those obtained by in vivo studies.