Human leukocyte interferon for the prevention of recurrences of herpetic keratitis.

A double-blind clinical trial of human leukocyte interferon is in progress for assessment of the effect of this substance on recurrences of herpetic keratitis. Although human leukocyte interferon is highly effective in preventing infection in owl monkeys (protection from infection and prevention of recurrences correlate well in lower animals), there is no difference between the frequency of recurrences in placebo-treated patients and that in interferon-treated patients. Forty-nine patients have been treated with interferon, and 46 have received placebo; there have been seven recurrences (with herpes simplex virus isolated) in each group. The interferon used is highly stable both in storage in the laboratory and in clinical use. Because the titer of interferon in this study (6.4 X 10(4) units/ml) may be too low to accomplish our prophylactic needs, attempts are being made to use the material in more concentrated form.