Effects of intradermal administration of streptococcal preparation OK-432 on interferon and natural killer cell activities in patients with oral cancer.

The streptococcal preparation OK-432 was used by intradermal administration as an immunotherapy in 18 patients with oral cancer, and the sera from patients during OK-432 treatment were serially assayed for interferon (IFN) activity by the plaque-reduction method with vesicular stomatitis virus in FL cells derived from human amniotic membrane. The type of serum IFN was characterized by acid-treatment and neutralization test with anti-IFN-alpha and anti-IFN-beta antisera. IFN-gamma was expressed for its titer as the residual IFN activity after neutralization with both antisera. An intradermal injection of OK-432 transiently induced IFN activity and 3 patterns in the type and level of the produced IFN were observed. Although most of the patients induced IFN-gamma and acid-stable IFN or only IFN-gamma, 2 patients seemed to be unresponsive to OK-432. When we examined the relationship between natural killer (NK) activity and IFN titer, a sharply declined NK activity was found immediately post OK-432 administration, and then NK activity stayed around the pretreatment level. Most of the tested patients' induced IFN-gamma, preceding the step toward the gradual increase in NK activity, decreased with OK-432. However, even in the patients showing no IFN induction with OK-432, a significant decrease of NK activity occurred.