Spontaneous and induced interferon production by peripheral blood mononuclear leukocytes from humans with herpes labialis.

Peripheral blood mononuclear leukocytes (PBML) were obtained from 44 individual human subjects within 1 to 66 days after the onset of an episode of recurrent herpes labialis. PBML did not spontaneously produce interferon (IFN) when maintained in cultures that contained medium only. Absence of detectable IFN could not be explained by delayed kinetics of production because no appreciable IFN was present in medium from 5-day-old cultures. IFN was produced when PBML were exposed to Newcastle's disease virus or to phytohemagglutinin. These findings suggest that spontaneous IFN production may not occur predictably after an episode of herpes labialis.