Importance of the density of the spleen cell suspension in culture for development of the immune response

Abstract

The number of antibody-forming cells (AFCs) formed at the end of incubation was shown to depend on the number of cells of a spleen suspension used to induce the primary immune response in vitro. With an increase in the “surface density” of the cells (the number of cells per cm2 of the bottom of the incubation vessel) the number of AFCs formed was reduced by 10–100 times although the total number of cells which survived at the end of incubation was not reduced or was only very slightly reduced. The effect was observed when either sheep's red cells or water-soluble antigen extracted from them was used as the antigen. It was independent of a deficiency of antigen or of nutritive substances and it was accompanied by a parallel overall decrease in the incorporation of thymidine-H3 into the cells in culture.