Staphylococcal protein A bound to Sepharose 4B is mitogenic for T cells but not B cells from rabbit tissues

The mitogenicity of protein A from Staphylococcus aureus bound to Sepharose 4B (SpA-S) was tested against mononuclear cells from normal rabbit spleens and Peyer's patches after using Sephadex G-10 adherence chromatography to deplete macrophages and Sephadex G-200 anti-rabbit F(ab')2 immunoabsorbent columns to obtain B-enriched lymphocytes. Macrophage-depleted unseparated lymphocytes and the B-cell-depleted (T-cell-enriched) fractions from both tissues consistently showed good mitogenic responses to SpA-S. In contrast, the B-cell-enriched populations from either tissue did not respond to SpA-S. Supplementary experiments employing glass adherence and T-cell autorosetting did not support the possibility that the more efficient immunoabsorbent method of B-cell isolation had in some way caused the unresponsiveness to SpA-S. These results indicate that SpA-S is mitogenic for rabbit tissue T cells but will not serve as a T-independent mitogen for rabbit tissue B cells.