Since interferon-alpha has a very broad spectrum of activity it has been investigated in several clinical settings in the HIV-infected population. KAPOSI'S SARCOMA: The rate of response to interferon-alpha is low in patients with low CD4 cell counts, but response rates of over 45% have been achieved in patients with higher counts. In 34 asymptomatic patients, the overall percentage of CD4 cells was higher in patients taking interferon-alpha compared to those taking a placebo and the rate of opportunistic infections was lower after a long-term follow-up. A relatively high dose of interferon-alpha was associated with predictable side effects. Lower doses have been used in combination with zidovudine. In a recent trial, 180 patients took either zidovudine alone, interferon-alpha alone or both drugs in combination. So far, the CD4 cell counts have been similar in all treatment groups. The rate of response shown by hepatitis B infection to interferon-alpha in patients with both hepatitis B and HIV has been reported as less than that in patients without HIV infection. Overall, studies have shown that approximately 37% of patients are cleared of hepatitis B DNA with 3 months of interferon-alpha treatment, compared with a 17% rate of spontaneous clearance. Among hepatitis C patients, 50-75% show a reduction in serum transaminases with 3 months of treatment. Interferon-alpha is of benefit in some HIV-infected patients, demonstrating efficacy in Kaposi's sarcoma, hepatitis B and hepatitis C.