Toxicity and efficacy of human leukocyte interferon for treatment of cytomegalovirus pneumonia after marrow transplantation.

Eight recipients of marrow transplants with cytomegalovirus (CMV) pneumonia diagnosed by open lung biopsy were treated with doses of human leukocyte interferon of 2 X 10(4)--6.4 X 10(5) units/kg per day to evaluate its toxicity after marrow transplant and its effectiveness against CMV infection. All eight patients died from pneumonia, and virus was still present in lung tissue from seven patients cultured after death. Interferon doses of less than or equal to 1.6 X 10(5) units/kg per day did not affect the circulating granulocyte count. Patients treated with higher doses had a decrease in circulating granulocyte count, but study of granulocyte-macrophage colony-forming cells in culture showed no evidence of toxicity to granulocyte progenitor cells. The effect on in vitro lymphocyte function was variable. Antibody production was not impaired. Interferon was not effective against established CMV infection. However, there was less hematologic toxicity than was anticipated, and the prophylactic use of interferon after marrow transplant is feasible.