Safety and tolerance of recombinant leukocyte A interferon in bone marrow transplant recipients.

Five bone marrow transplant recipients with cytomegalovirus infections were treated with pure recombinant leukocyte A interferon produced by recombinant DNA technology from Escherichia coli. All five patients had documented interstitial pneumonia. The daily intramuscular dose of interferon ranged from 18 X 10(6) to 50 X 10(6) U; the mean duration of therapy was 11.0 days (range, 5 to 18 days). Two patients recovered, one improved, and two died. Clinical side effects (usually fever and chills) occurred in three patients. A 60% or greater reduction in the pretherapy peripheral granulocyte counts occurred in four patients, and four patients had a 37 to 80% reduction in their pretherapy platelet counts. Hematological toxicity was reversible, and there was no loss of marrow graft function. The toxicity of pure recombinant leukocyte A interferon in marrow transplants is similar to that of partially pure leukocyte interferon derived from human cells. Further controlled studies to establish the efficacy of recombinant leukocyte A interferon in marrow transplants are warranted but may be limited by hematological toxicity.