Heat-killed, preservative-free preparations of strain CN 6134 Corynebacterium parvum have been demonstrated to induce interferon in cultures of normal adult human T-lymphocytes. C. parvum was also shown to induce human T-lymphocytes to proliferate in vitro. The maximum interferon and proliferative response was observed 7 days after initiation of culture at a final C. parvum concentration of 140 µg/ml. Human monocyte-derived macrophages did not produce interferon in response to C. parvum or in response to products of C. parvum-stimulated T-lymphocytes. The addition of macrophages to cultures of T-lymphocytes did not significantly enhance the production of interferon by the T-lymphocytes; however, it did significantly enhance the proliferative response to C. parvum. C. parvum can also enhance the production of interferon by T-lymphocytes stimulated with phytohemagglutinin in the presence of macrophages, and the amount of interferon produced in the presence of both agents was greater than the sum of the amounts of interferon stimulated by each agent acting alone. The type of interferon produced by T-lymphocytes in response to C. parvum is similar to type II or immune interferon, because it was labile to low pH and heat. Thus, a link has been found between two agents, C. parvum and interferon, both of which have in common antitumor properties and the ability to modulate the immune response.
This work was supported by Grants AI 12481 and CA 14508 from NIH and by a grant from the Burroughs Wellcome Company. A portion of the work was presented at the Oncology section of the annual meeting of the American Society for Clinical Investigation, May 2, 1977 (11).