TreatmentUpdate 69, Volume 8, No 5; July 1996
Sean Hosein

Certain drugs such as:

* amphotericin B

* Bactrim/Septra

* flucytosine

* ganciclovir

and anti-cancer drugs may be toxic for bone marrow. Use of these drugs may reduce levels of white blood cells including CD4+ and CD8+ cells and may make patients less resistant to infections. Drugs such as G-CSF (granulocyte colony-stimulating factor, Neupogen) stimulate the bone marrow causing levels of white blood cells to increase. One research team in San Francisco was treating six subjects with G-CSF and found some interesting results.

Study details

All subjects had AIDS and an average CD4+ cell count of 20 cells. Their bone marrow was not producing normal levels of white blood cells because some subjects had certain infections, cancer or the drugs they were using were toxic to the bone marrow (see list above). Subjects received injections of G-CSF between 3 and 5 ug/kg of body weight under the skin three times weekly for 2 weeks, or until their "[white blood cell] count reached the normal range."

Results

On average, levels of white blood cells increased by 200 %. The average CD4+ cell count rose from 20 cells to 32 cells. The average CD8+ cell count rose from 288 to 494 cells. These changes were statistically significant. The most dramatic change was seen in levels of natural killer (NK) cells which rose from an average of 36 cells to 85 cells, an increase of 136%.

Important results

The researchers think that the increase in CD4+ cells was too small to have any impact on the health of the six subjects. CD8+ and NK cells (CD56+) play an important role in fighting HIV infection. Researchers do not know the impact of long-term G-CSF therapy on cell counts. Other studies need to be done to find out what effect increased CD8+ and NK cell counts might have on the immune systems of people with HIV/AIDS. One concern is that use of G-CSF may cause increased production of HIV. However, most experiments with cells and on other HIV-infected subjects have shown that production of HIV does not increase when G-CSF is used. This may be due to the increased numbers of CD8+ and NK cells, which suppress replication of HIV.

REFERENCES:

1. Stricker RB and Goldberg B. Increase in lymphocyte subsets following treatment of HIV-associated neutropenia with granulocyte colony-stimulating factor. Clinical Immunology and Immunopathology 1996;79(2):194-196.

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