The identification of a way to single out those HIV+ infants at highest risk for the rapid and aggressive development of AIDS means that doctors may now target these babies for early, powerful therapies, report Emory University researchers in this week's New England Journal of Medicine.
Infants who test positive for HIV can generally be divided into two groups: those in whom AIDS symptoms develop quickly and aggressively -- within the first one to two years of life -- and those in whom symptoms may not appear for a number of years. Until now, doctors have not known conclusively how to predict which HIV+ infants will fall into which category.
Thymus dysfunction was common to the majority of HIV+ infants whose AIDS symptoms progressed rapidly, reports Athena P. Kourtis, M.D., Ph.D., fellow; Andre J. Nahmias, M.D., M.P.H., director, Division of Infectious Diseases, Epidemiology and Immunology, Department of Pediatrics, Emory University School of Medicine; and their colleagues, in their study of 232 infants below six months of age. While the thymus organ, located in the chest, becomes virtually nonfunctional in older age, it serves the important function in children of producing T lymphocyte immune cells. In particular, it produces the CD4+ helper T cells that are depleted by the AIDS virus. It also produces CD8+ cytotoxic T cells. Both types of cells are involved in resistance to HIV, as well as to many other microorganisms.
The researchers postulated that certain strains of the AIDS virus not only deplete mature CD4+ and CD8+ T cells in infants, but also inhibit production of these cells by damaging the thymus. Thus, certain infants would exhibit particularly low levels of CD4+ and CD8+ T cells -- and would develop AIDS symptoms sooner. This tendency to delete both types of T cells is in contrast to what occurs in most other HIV-infected children or adults; usually when the number of CD4+ T cells decreases, the number of CD8+ T ce
Contact: Sarah Goodwin
Emory University Health Sciences Center