September 27, 2001

Immune System May Age Prematurely in HIV+ Kids

NEW YORK (Reuters Health) - The immune system of HIV-infected children appears to undergo accelerated aging, according to a report published in the September issue of the Journal of Allergy and Clinical Immunology.

HIV attacks immune system components known as CD4+ T cells and CD8+ T cells. In people with HIV, apoptosis--the body's method for destroying abnormal cells--is a leading cause of the death of CD4+ T cells.

While several studies have investigated the death of immune system cells, or lymphocytes, in adults with HIV, few have looked at patterns of lymphocyte death in children infected with the virus.

To investigate, Dr. Andrea Cossarizza from the University of Modena in Italy and colleagues evaluated the expression of markers for apoptosis on lymphocytes in 39 children who had contracted HIV from their mothers. All blood samples were obtained before the children began treatment with the potent cocktail of anti-HIV drugs known as highly active antiretroviral therapy.

These children were compared with a similar group of 36 healthy children.

Cossarizza and her colleagues found the number of CD4+ and CD8+ T cells in the HIV-positive children decreased with age. Expression of CD95+, a cell marker associated with apoptosis that is known to increase with age in uninfected individuals, also increased with age.

HIV-infected children were also more likely than healthy children to have T cells that lacked the anti-apoptotic cell marker CD28.

Blood samples from infected children also showed a decrease in B lymphocytes and an increase in natural killer cells compared with samples from healthy children, the investigators note. Further analysis of lymphocytes from infected children revealed an enhanced susceptibility to apoptosis and damage to the mitochondria, the cellular engines that produce energy from food.

These changes suggest that the immune system ages prematurely in children with HIV, Cossarizza and her colleagues conclude.

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