Requirement of the CD8 + or CD4 + T lymphocyte subsets for the rejection of lymphoma and fibrosarcoma grafts studied in gene knockout hosts

Rejections of the retrovirus induced lymphomas (ALC and RBL-5) and the methylcholanthrene (MCA) induced fibrosarcoma (MC57X) grafts were tested in syngeneic CD8 and CD4 single and double knockout C57BL/6 mice. The results with the lymphomas showed that the CD8 + T cell deficiency prevented the development of rejection response induced by immunization. Deficiency of the CD4 + T subset abrogated also the rejection of ALC. Immunity against the fibrosarcoma cells developed in both type of single knockout mice, but not in the ones which lacked both CD4 + and CD8 + T cells. Thus CD8 + T cells were required for rejection of the lymphoma cells, while the CD4 + T cells only mediated a weak response. In absence of CD8 + T cells, CD4 + T cells were sufficient to reject the fibrosarcoma cells.