Human nasal mucosal responses to topically applied recombinant leukocyte A interferon.

Healthy adults were randomly assigned to receive intranasal sprays of recombinant leukocyte A interferon (IFN; 9 X 10(6) U per day) or placebo once daily for four or 10 days. Scrape nasal biopsy specimens stained by hematoxylin and eosin and mucosal punch biopsy specimens stained by immunoperoxidase techniques with monoclonal antibodies to lymphocyte subsets were collected before and after exposure. Blinded analysis of the punch biopsy specimens by two pathologists found increased degrees of lymphocyte infiltration compared with preexposure samples in 56% of IFN vs. 0% of placebo recipients at four days (P = .008) and 60% of IFN vs. 10% of placebo recipients at 10 days (P = .057). By immunoperoxidase staining the cellular infiltrates were primarily in the subepithelium and comprised principally (mean, greater than or equal to 84%) T lymphocytes. In the 10-day IFN recipients, subepithelial T helper (Leu-3):T suppressor (Leu-2) cell ratios ranged from 2:1 to 5:1. The number of distribution of B (Leu-14) or natural killer (Leu-7) cells did not appear affected by IFN.