Effects of CD4+ and CD8+ T cells in tumor-bearing mice on antibody production.

The function of T cell subsets in tumor-bearing mice was examined using an in vitro culture system of anti-(sheep red blood cell) antibody production, which is known to be dependent on T cells. The helper function of T cells of fibrosarcoma-MethA-bearing mice in antibody production decreased with the tumor stage of the mice. T cells were separated into CD4+ and CD8+ cells for further analysis of T cell subsets by the panning method using monoclonal antibodies. The helper function of CD4+ T cells in antibody production began to decrease significantly in tumor-bearing mice 1 week after the tumor transplantation. On the other hand, the suppressive function of CD8+ T cells was retained and had not decreased in the mice even 3 weeks after the transplantation. The same changes in function of CD4+ and CD8+ T cells were also observed in Meth1-bearing mice. These results suggested that this tumor-associated immunosuppression in antibody production is attributable to the decrease in helper activity of CD4+ T cells and the maintenance of the suppressive activity of CD8+ T cells.