Co-operative cellular interactions in the generation of adoptively-transferred murine IgA responses.

The adoptive transfer system was initially used to document the requirement for co-operation between hapten-primed and carrier-primed lymphocytes in generating secondary IgA antibody responses. Studies employing anti-theta antiserum and complement to deplete T cells showed that carrier-specific theta-bearing cells are required for IgA responses. Furthermore, non-specific T-cell help could be provided by transfer of normal allogeneic spleen cells into irradiated recipients. When limiting numbers of 'educated' thymus cells were added to a constant number of spleen cells, depleted of T cells, IgM responses were not affected while both IgG and IgA antibody responses were shown to be dependent on the numbers of thymus cells injected. These results provide direct evidence for the participation of theta-bearing T lymphocytes in IgA anti-TNP antibody responses and suggest that IgA lymphocyte precursors may be inherently more sensitive than IgM B cells to the regulatory effects of helper T lymphocytes.