Relationship between the priming effects of interferon (IFN)-alpha and -gamma and the standard IFN production by peripheral blood leukocytes was evaluated in 25 volunteers (13 men and 12 women, mean age 35.3 years). Priming of IFN-alpha and IFN-gamma production positively correlated with the standard IFN-alpha and IFN-gamma synthesis, respectively. On the other hand, primed production of IFN-alpha negatively correlated with that of IFN-gamma. Possible role of types I and II IFN interactions in the maintenance of physiological regulatory balance is discussed.