The immune response to heterologous red cells in mice

Abstract

Several parameters such as dosage and schedule of antigen injection were examined. The effect of a single intraperitoneal or intravenous injection of various amounts of sheep red cells (SRBC) was studied over a dose range of more than 10⁵. Approximately 5×10⁷ SRBC was the optimal amount of antigen beyond which no further increase in titre occurred.

Multiple injections and overloading the organism with large amounts of SRBC did not result in a depression of the immune response.

Immunization with SRBC incorporated into incomplete Freund's adjuvant was slightly inferior to immunization with SRBC suspended in saline. The response depended on the antigen concentration in the adjuvant mixture rather than on the absolute amount of antigen injected.

Early in immunization antibodies against SRBC belong to the 19S class and change gradually into 7S antibodies. 19S and 7S haemolytic activity was mercaptoethanol-sensitive.

From absorption experiments it was concluded that the mouse antibody against SRBC has specificities other than anti-Forssman, anti-mononucleosis and anti-serum sickness and is directed against an isophilic heat-labile antigen(s).