TreatmentUpdate76. 9(2): 9; March, 1997
Sean Hosein

Background and study details

IL-2 is a chemical made by the immune system which helps T cells grow and fight infections. During the course of HIV infection, production of IL-2 falls, so some researchers think that supplements of IL-2 may be useful for PHAs. Doctors in Sydney, Australia, gave 5 subjects (whose CD4+ counts ranged between 200 and 500 cells), occasional infusions of IL-2 directly into a vein (intravenous, iv) at a dose of 12 million units/day for 5 days every 8 weeks. Six other subjects received smaller doses of IL-2 injected under the skin on days 1 and 3 of every 8th week. Four others received anti-HIV therapy alone. All subjects who received IL-2 were also taking anti-HIV drugs. Doctors monitored the subjects for 1 year.

Results

Those subjects receiving iv IL-2 had an average increase of 300 CD4+ cells while those who received shorter courses had an increase of 200 CD4+ cells. Subjects receiving anti-HIV drugs alone lost about 100 CD4+ cells during the study. The researchers did not find any ?significant? changes in levels of HIV in the blood. The ability of the immune system to respond to infections (in simulated tests) increased slightly among subjects who received IL-2, while it fell by 50% among subjects who received anti-HIV drugs alone. The immune system?s ability to recognize and attack HIV was not improved in subjects receiving IL-2. Most importantly, use of IL-2 does not permanently return immunity lost or damaged because of HIV infection. It is questionable whether the increased numbers of CD4+ cells are even of any benefit. All IL-2 seems to do is stop CD4+ cells from dying. These cells were scheduled for death anyway because they were defective, old or immunologically exhausted.

Beta-carotene

When the plant colouring beta-carotene is cut in half in the intestine, 2 molecules of vitamin A are formed. This conversion from beta-carotene to vitamin A is done only when needed and does not lead to toxic build up of vitamin A. Since this vitamin is important for the immune system, researchers gave 30 HIV-infected subjects who did not have a vitamin A deficiency beta-carotene 180 mg/day for 4 weeks. This product was nontoxic and did not change the level of CD4+ cells or the amount of HIV in the blood of treated subjects. As one Canadian researcher noted, these results do not mean that supplements of beta-carotene may not be useful for maintaining health. However, this study was not designed to measure such an outcome.

A vaccine for MAC

In an attempt to stimulate the immune system into producing the chemicals necessary to keep MAC (Mycobacterium avium complex) infection under control, researchers in New Hampshire, Boston and Chicago used a vaccine made from bacteria related to TB (to which MAC is also related) called M. Vaccae. Preliminary results show that the vaccine, which is made from dead bacteria, is safe in both adults and children. A detailed report on this research will appear in a future issue of TreatmentUpdate.

REFERENCES:

1. Kelleher AD, Roggensack M, Emery S et al. Effect of IL-2 therapy on T cell responses to mitogens, recall and HIV-specific antigens. Oral presentation 35.

2. Lempicki RA, Pavlick MV, Donoghue ET, et al. IL-2 relieves G1 cell cycle arrest in CD8+ T cells from HIV-positive individuals. Abstract 462.

3. Nimmagadda AP, Burri BJ, Neidlinger T, et al. Effect of b-carotene on HIV RNA and CD4+ counts. Abstract 76.

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