Potentiation of lymphocyte natural killing by mixtures of alpha or beta interferon with recombinant gamma interferon.

Human lymphocytes were treated with human alpha (IFN-alpha), beta (IFN-beta), or recombinant gamma (IFN-gamma) interferons separately or in combination to determine their ability to enhance natural killing against mouse L cell targets. Our results showed that recombinant IFN-gamma was approximately 50 times more active per unit of antiviral activity than either IFN-alpha or IFN-beta. Moreover, the levels of natural killing by lymphocytes treated with combinations of IFN-alpha and IFN-beta were additive, whereas combinations of recombinant IFN-gamma and IFN-alpha or recombinant IFN-gamma and IFN-beta were synergistic. The development of natural killing in lymphocytes treated with recombinant IFN-gamma did not occur more rapidly but reached higher levels (62%) than that observed with lymphocytes treated with IFN-alpha or IFN-beta (15%). The results suggest the importance of IFN-gamma and mixtures of IFN-gamma with IFN-alpha or IFN-beta in the enhancement of natural killing activity against virus infections and neoplasia.