Philadelphia -- Adolescents infected with HIV were found to have a surprisingly high number of certain immune system cells, according to a research team led by an immunologist at The Children's Hospital of Philadelphia. In studying 94 HIV-positive patients, aged 13 to 19, the researchers found a "striking increase" in the number of circulating CD8 memory cells, which play a major role in attacking the virus that causes AIDS.

The study offers intriguing hints of how the immune system of adolescents differs from those of younger children and adults, according to the study's lead author, Steven D. Douglas, M.D., Chief of Immunology at Children's Hospital, and co-author Bret Rudy, M.D., of the same institution. Although adolescents represent the largest segment of the U.S. population newly infected with HIV, relatively little is known about the relative proportions of different blood cells in teenagers' immune systems. The study, published in the September 1999 issue of the journal AIDS, is the first attempt to establish reference measurements for cells that act as immune system markers for both HIV-infected and healthy adolescents. At the time of the study, the infected teenagers had not been treated with the antiretroviral medicines commonly used against AIDS.

The researchers also found significant differences in immune system cell populations between male and female adolescents. These differences may be related to hormonal and developmental changes that occur during adolescence. Future studies will explore how the immune system of adolescents functions during HIV infection.

Blood samples were drawn from 243 HIV-positive and HIV-negative adolescents at 16 clinical sites throughout the United States participating in the Adolescent Medicine HIV/AIDS Research Network, established by the National Institutes of Health and the Health Resources and Services Administration. As part of that network, the REACH Project (Reaching for Excellence in Adolescent Care
'"/>

Contact: Maria Stearns
stearnsm@email.chop.edu
215-590-4091
Children's Hospital of Philadelphia
23-Sep-1999