A Method of Reduciiig the Incidence of the Secondary Syndrome in Allogenic Marrow Transplantation

I N A PREVIOUS PAPER4 it was observed that the lymph node cells of C57B16 mice, intravenously injected at the same time as bone marrow cells into F1 hybrids ( C57B16 x DBA2) after total irradiation with 500 r, show intensive proliferation in the lymph nodes and the spleen, particularly (luring the first 7 days following the injection. Subsequently the proliferation diminishes; lytic processes are set in motion and by the 15th day the lymphoid tissue becomes first hypoplastic and! then aplastic. In the genetic arrangement used, the graft is immunized against the DBA2 antigens of the host, as shown l)y the rapid death of the mice and the intensity of the basophilia of the cells during the proliferative phase, when the cells often assume a plasmocytic aspect without being real plasmocytes because they have no endoplasmic reticulum.2 The host, however, is not immunized against the graft since it 055C5SCS its antigen. Consequently we ventured to forward the hypothesis that, under certain conditions ( particularly when it is relatively abundant, as in the experiment described), the antigen may be noxious to immunologically competent cells which are immunized against it.4 It was hoped that an in vitro contact between the recipient’s antigens and the donor’s hemopoietic cells,