Proliferative response of human T lymphocytes to a vaccinal preparation of ribosomes from Streptococcus pyogenes

The in vitro lymphocyte-activating properties of a ribosomal preparation of Streptococcus pyogenes were investigated. The preparation was mitogenic for human lymphocytes with a peak of 3H-thymidine incorporation occurring after 3-5 days of culture. The response was abolished by removal of CD3-positive cells and by alteration of accessory cells by exposure to L-leucine methyl ester. Most of the cells synthesizing DNA at the end of the culture expressed CD4 or CD8 but not CD20 antigens. No immunoglobulin synthesis was demonstrable. Although the same preparation was shown to be a T-independent polyclonal B-cell activator of murine cells, it preferentially triggers T cells in humans.