Human leukocyte interferon administration to patients with symptomatic and suspected rabies.

Body fluids and brain tissue from rabid human patients have demonstrated only low titers of interferon. Therefore, pharmacokinetic studies of systemically administered and locally injected leukocyte interferon were performed in 2 North American patients with suspected rabies who showed no clinically important side effects of this therapy. Similar therapy was given to 5 patients with symptomatic rabies in Europe and America. Although no prolongation of the clinical course was seen in 3 patients given high-dose intraventricular and systemic therapy, treatment was not initiated until between 8 and 14 days after symptoms were seen. The intraventricular dosage regimen produced cerebrospinal fluid levels that appeared to fall progressively over the 24 hours after injection and demonstrated good but somewhat delayed distribution into the lumbar sac. Titers produced by this therapy were 30- to 10,000-fold higher than those normally observed in this infection, however. In the patients treated at the highest dosage, a diminished and delayed antirabies neutralizing antibody titer was observed, probably a result of the administration of the exogenous interferon.