Teen-agers bounce back quickly after HIV assault
Research holds hope for reconstituted immunity
Researchers have found some evidence that the immune systems of HIV-infected adolescents could be reconstituted after highly active antiretroviral therapy.
Unlike adults, teen-agers who are infected with HIV have a high number of CD8-naive T lymphocytes produced by the thymus gland. The study shows that the HIV-infected teen-agers had a greater number of CD8 cells than did a control group of uninfected teens.
"These data would support the concept and are by no means definitive that these patients may have a great opportunity for complete and endurable recovery," says Steven D. Douglas, MD, section chief of immunology laboratories at The Children’s Hospital of Philadelphia. Douglas also is the medical director of clinical immunology laboratories, a professor of pediatrics, and the associate chair of the department of pediatrics at the University of Pennsylvania Medical School in Philadelphia. "The research suggests adolescent patients have a more robust immune system, and we should start treating them very aggressively early on," he adds. "But that’s speculation."
Researchers analyzed T-lymphocyte subset data for 192 HIV-infected youths and 78 youths who were not infected with HIV.1
The study found a predictable reduction in total CD4 cell count among the HIV-infected youths when compared with the youths who were not infected with HIV.1 The surprising finding was that total CD8 cell counts were significantly higher in the HIV-infected teen-agers than in the HIV-negative teen-agers.
The increase in total CD8 cells resulted from increases in both naive and memory CD8 cells1 and was particularly pronounced in youths who had a higher CD4 count and were in early stages of HIV infection. This group had a significant increase in naive CD8 cells when compared with youths who were HIV-negative.1 HIV-positive youths with lower CD4 cell counts still had a higher number of memory CD8 cells than did HIV-negative youths.1
The research supports a theory that HIV-infected adolescents have functioning thymic tissue and that their immune systems are more robust than adults with HIV infection. Therefore, HIV-infected youths may have better responses to neoantigens and cytotoxic T-lymphocyte responses to HIV than either HIV-infected adults or children.1
The study highlights the benefits of early detection of HIV infection among teen-agers, followed by early treatment, Douglas says. The research is continuing, he adds, and eventually may cast light on how CD8 cells function.
Reference
1. Douglas SD, Rudy B, Muenz L, et al. T-lymphocyte subsets in HIV-infected and high-risk HIV-uninfected adolescents. Arch Pediatr Adolesc Med 2000; 154:375-380.
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