Rat thoracic duct cells as a substitute for T cells and carrier in the antibody response of mouse spleens deficient in thymus cells.

Abstract

The immune response of mouse spleen cells to sheep red blood cells (SRBC) in vitro depends on the presence of thymus derived helper lymphocytes (T cells). This has been demonstrated by depleting spleen cells of T cells by treatment with complement and anti-θ serum1 and showing that the in vitro immune response can be restored by addition of antigen sensitized syngeneic or allogeneic T cells2. Although un-sensitized syngeneic T cells usually fail to restore the immune response of spleens deprived of T cells (B spleens), unsensitized allogeneic thymus cells do so3. This “allogeneic effect” can act through factors released in the culture supernatant of allogeneic lymph cell mixtures4. We show here that xenogeneic (rat) thoracic duct cells (RTDC), whether antigen sensitized or not, can restore an in vitro immune response of thymus-depleted mouse spleen cells. They stimulate antigen specific T cell responses by two mechanisms. In one, they substitute both for the carrier and the carrier-specific T cells and thus stimulate T cell response to a low molecular weight hapten. In the other, they stimulate T cells through amplification of the effect of a small number of carrier-specific mouse T cells.