BETHESDA, Md--Intermittent infusions of interleukin-2 (aldesleukin,
Proleukin) in HIV-infected patients produced "substantial
and sustained" increases in the number and percentage of
CD4 cells, with no associated increase in plasma HIV RNA levels,
says Joseph A. Kovacs, MD, and his associates at the National
Institutes of Health (NIH).
The study involved 60 HIV-infected patients with baseline CD4
counts above 200/mm³ who were randomly assigned to receive
either IL-2 plus anti-retroviral therapy or antiretroviral therapy
Among the patients receiving IL-2 (every 2 months for six cycles
of 5 days each, at a starting dosage of 18 million IU/day), mean
CD4 counts increased from a baseline of 428 to 916/mm³ at
month 12, whereas counts declined in the control group from 406
to 349/mm³ (N Engl J Med 335:1350-1356, 1996).
Says Dr. Kovacs, "57% of the patients treated with IL-2 had
an increase of more than 50% over the baseline CD4 count at the
end of approximately 1 year."
Furthermore, these increases have been sustained for more than
2 years in patients continuing to receive IL-2. In five patients,
CD4 counts remained above 1,000 for at least 18 months after IL-2
was stopped. "To date," Dr. Kovacs says, "no combination
of antiretroviral agents has been shown to be capable of inducing
increases in CD4 counts of this magnitude or duration."
Sustained suppression of viral replication through the use of
protease inhibitors in combination with other agents "may
lead to improved CD4 responses to IL-2 therapy," he says,
citing preliminary evidence from a study of IL-2 plus indinavir
A "crucial" observation, Dr. Kovacs says, is that use
of IL-2 did not cause long-term increases in plasma viral load.
The two groups did not differ significantly, he says, in plasma
HIV RNA or p24 antigen levels during treatment.