Interleukin-2 (IL-2, Proleukin)

March 2007 View PDF En español

Who should use it?

IL-2 is not currently approved or proven for use in treating HIV. Use in people with HIV is experimental. IL-2 has been studied in people with a wide spectrum of CD4+ cell counts. Emerging information suggests that a person’s CD4+ cell count at the time of starting IL-2 might be useful in predicting the outcome of therapy. This information may indicate how quickly the CD4+ cell count might rise and how high it will reach. Still, even people with low CD4+ cell counts when starting IL-2 appear to experience higher CD4+ cell increases than those seen from anti-HIV therapy alone.

Studies suggest that IL-2 therapy can be used safely (though with significant side effects) by people at all levels of CD4+ cell counts. IL-2 provides the greatest increases in CD4+ counts when it is used together with anti-HIV therapy. The most pronounced and immediate increases in CD4+ cell counts are seen among people who start IL-2 therapy together with anti-HIV therapy while their CD4+ cell counts are above 300, and preferably when their lowest ever CD4+ cell count (nadir count) has never been below 200.

There are several situations in which IL-2 therapy should be avoided or approached with extreme caution. As a general rule, it is discouraged for people with high detectable viral loads, since IL-2 can at least temporarily cause the viral load to increase even more. Some doctors urge caution using IL-2 in anyone who has a detectable viral load at all. However, this strict position seems unnecessary to others, since all early studies of IL-2 that showed benefit were conducted before potent three-drug anti-HIV therapy made it possible to reduce viral load to undetectable levels.

People with an active infection (e.g. opportunistic infection) should avoid IL-2 or use it carefully. IL-2 can produce temporary immune suppressive effects. Therefore, anyone with an infection should wait until the condition has resolved before using IL-2.
This also applies to people currently on an IL-2 regimen. If you have an infection, consider waiting until it’s resolved before starting your next IL-2 cycle. If you’re taking IL-2 and develop an infection, delay IL-2 therapy until it’s resolved.

People with heart problems should also be cautious since IL-2 decreases blood pressure. People on medicine to lower blood pressure should consider either avoiding IL-2 therapy or consider stopping blood pressure medication, in consultation with a doctor, during the five-day courses of IL-2. The combination of IL-2 with blood pressure lowering medication could result in dangerously low blood pressure levels that could be fatal.

IL-2 should not be used by people with lung disease. People with autoimmune diseases, including Crohn’s disease, psoriasis and rheumatoid arthritis should not use IL-2, or use it with great caution because it may worsen these conditions. There are concerns that IL-2 therapy might also worsen diabetes, so people with diabetes and people with signs of insulin resistance should be cautious. Because IL-2 side effects include flu-like symptoms, including fatigue, people experiencing extreme fatigue are encouraged to seek treatment for its cause and delay IL-2 therapy until the condition has resolved. In rare instances, IL-2 has caused hypothyroidism and thus should not be used by people with thyroid problems.

Pregnant women and children

IL-2 has not been studied in pregnant women. In studies, women who become pregnant must stop IL-2 but can remain in the study. IL-2 can raise bilirubin levels which may cause serious harm to the developing child. Studies of IL-2 in children are ongoing.

What does the research show?

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