[Activation of DNA synthesis in lymphocytes of guinea pigs induced by Staphylococcus antigens]

The proliferative activity of lymphocytes in the spleen and the thymus of intact guinea pigs in response to protein A isolated from Staphylococcus aureus, strain Cowan-1, and the corpuscular antigens of Staphylococcus aureus, strains Cowan-1 and Wood-46, has been studied. All Staphylococcus aureus antigens have been shown to have mitogenic activity in respect of splenic cells and to exert no influence on the synthesis of DNA in thymic lymphocytes. The mitogenic effect of protein A on splenic lymphocytes depends on the content of immunoglobulins in the serum used as culture medium. The stimulating action of Staphylococcus aureus, strain Cowan-1, on splenic lymphocytes is more pronounced than that of strain Wood-46; this fact is mainly due to the presence of protein A in the cell wall of the former strain. The antigens used in this study are probably polyclonal mitogens for the splenic lymphocytes of intact guinea pigs. This fact is indirectly confirmed by the results of experiments on incorporation of 3H-thymidine into splenic lymphocytes during their cultivation together with some T and B-mitogens.