Thymus Dependence of Antibody Response: Variation with Dose of Antigen and Class of Antibody

Abstract

CELLS which produce γG antibody are more dependent on the presence of a thymus than are those which produce γM antibody¹. This conclusion is based on experiments carried out in lethally irradiated mice repopulated with foetal liver cells and grafted with a syngeneic thymus. Sinclair and Elliott² have published data which suggest that the suppressive effect of thymectomy can be partly over-ridden by large doses of antigen. In normal mice immunized with sheep RBC the antigen–dose/plaque-forming cell (PFC) response is different for each class of antibody produced and most plaque-forming cells produce only one class of immunoglobin (unpublished work of D. W. Dresser, H. L. Anderson and H. H. W.). We have immunized thymectomized and non-thymectomized mice with different doses of sheep red blood cells (RBC) and have measured the response in terms of cells producing four different classes of immunoglobulin.