Induction of interferon by streptococcus pyogenes extracellular products.

Lymphocyte-activating streptococcal exoproteins, which were previously characterized, have been tested for their capacity to induce interferon in vitro. Two out of the 3 different streptococcal fractions, studied on mice splenocytes, were shown to elicit the production of a significant amount of interferon. A large proportion of the interferon detected in the supernatants from mice activated spleen cells was acid-labile interferon. The highest level of interferon titer was obtained with the streptococcal fraction identified as the erythrogenic toxin.