A Study of Passive Immunization Against a Transplanted G+ Leukemia with Specific Antiserum.

Abstract

Antiserum with high titers of cytotoxic antibody against G+ leukemia cells can be prepared in inbred rats by immunization with histocompatible rat leukemias induced in the same inbred strain by wild-type Gross virus. Under these conditions heteroantibody and isoantibody to normal tissue antigens are not formed. Passive immunization with this antiserum was successful against a G+ transplanted mouse leukemia but not against a G- mouse leukemia of the same inbred strain. These results conform to the specificity of the antiserum for G+ cells, as shown by the cytotoxic test in vitro. Complete protection can be achieved in some mice by serum given as late as 3 days after intravenous inoculation of leukemia cells. Protected mice are not immune to rechallenge with minimal numbers of G+ leukemia cells after the transferred G antibody has been cleared.