gamma Interferon production appears to predict time of recurrence of herpes labialis.

Peripheral blood mononuclear cells separated from the blood of 29 volunteers within 3 wk of the onset of recurrent oral herpes labialis spontaneously secreted IFN-gamma (and small amounts of IFN-beta) into the culture medium in varying amounts (mean = 77 U/ml, SE = 17). However, interferon could not be detected in the serum of 10 of these patients tested. In the group as a whole, peak levels of interferon were secreted in vitro at 6 to 20 days after the onset of herpes labialis. Serial studies in eight patients showed peak production in the second or third week, with subsequent decrease to undetectable levels at 6 wk. A strong correlation between peak supernatant interferon level and the time to the next recurrence of herpes labialis in each patient was noted (r = 0.82, p less than 0.0001). Herpes simplex antigen-stimulated mononuclear cell cultures from each patient produced a mixture of IFN-alpha and IFN-gamma. A less marked but still significant correlation was noted between the peak mixed interferon level and the inter-recurrence interval (r = 0.52, p less than 0.005). These results suggest that a recurrent herpes labialis acts as an in vivo stimulus to the induction of IFN-gamma-producing cells that circulate in peripheral blood. The IFN-gamma produced is either a direct determinant of frequency of recurrence of herpes or a quantitative marker for other cellular immune events determining frequency.