[Purification and properties of non-specific streptococcal extracellular mitogens].

Two immunologically different mitogens have been purified from culture fluid of growingStreptococcus pyogenes (group A). These substances were shown to be highly active on human and rabbit lymphocytes from peripheral blood, thymus and spleen, and less active on AKR mice thymocytes and splenocytes as well as on Nude mice splenocytes. These substances therefore appear as T-cell mitogens. Their effect on B cells remains to be investigated.