“Nonspecific” Stimulation of Lymphocyte Transformation by Cellular Fractions and Acid Extracts of Group a Streptococci

Abstract

Abstract Hot hydrochloric acid extracts of group A streptococcal cells of types 5, 12 and 19 induced “nonspecific” blast-transformation and increased thymidine-14C incorporation by adult and cord blood lymphocytes of normal human donors. A similar degree of transformation was induced by preparations of streptococcal cell walls and cell membranes and by hot acid extracts of these cell components. Streptococcal cytoplasm was found to contain an inhibitor of phytohemagglutinin-induced transformation and of spontaneous transformation of cord blood lymphocytes. Treatment of streptococcal cytoplasm with hot hydrochloric acid resulted in the appearance or release of lymphocyte transforming activity in such preparations. The lymphocyte transforming activity of streptococcal acid extracts was unaffected by digestion with ribonuclease, trypsin, chymotrypsin, and pepsin. After gel filtration on Sephadex G-75, acid extracts of streptococcal cell membranes, cell walls and cytoplasm all exhibited their major transforming activity in a peak with maximum at Kd 0.36, suggesting a similar average molecular size for the transforming agent or agents derived from these components. The “nonspecific” mitogenic activity of acid extracts of streptococcal cells resembled that of streptolysin S preparations with respect to enzyme susceptibility and dose-response. Hot acid-treated streptolysin S preparations retained most of their transforming activity, while their hemolytic activity was completely destroyed. These data raise the possibility that the transforming activities of streptococcal cell acid extracts and of streptolysin S preparations are attributable to a similar or identical constituent.