Important note: Information in this article was accurate in November 2001. The state of the art may have changed since the publication date.AIDSWEEKLY Plus; Monday, November 12, 2001
Michael Greer, Senior Medical Writer
NewsRx -- Helper T cells that recognize the HIV Gag protein play a significant role in the body's immune response to the virus, according to researchers in the United States.
"Mounting evidence suggests that human immunodeficiency virus type 1 (HIV-1) Gag-specific T helper cells contribute to effective antiviral control, but their functional characteristics and the precise epitopes targeted by this response remain to be defined," explained Eric S. Rosenberg and colleagues at Harvard Medical School, Massachusetts General Hospital, the Fenway Community Health Center in Boston, and Thomas Jefferson University in Philadelphia.
Rosenberg and coworkers elucidated the mechanics and targets of helper T cell antiviral responses in their report in the October 2001 issue of the Journal of Virology.
The researchers cloned Gag-specific helper T cells from infected patients with strong anti-Gag responses. These CD4 cells were able to target multiple Gag epitopes, they said, including a minimal peptide in the protein's cyclophilin binding domain.
Recognition of Gag epitopes triggered a Th1-type response, study data showed, with (gamma) interferon release and increased proliferation by CD4 cells. Moreover, antigen exposure induced cytolytic activity by helper T cells, with extracellular cytolytic markers seen at levels determined by antigen doses.
Gag-induced cytolysis appeared to be mediated by perforin (Multiple effector functions mediated by human immunodeficiency virus-specific CD4 & & + & & T-cell clones, J Virol 2001 Oct;75(20):9771-9).
"These data indicate that T helper cells can target multiple regions of the p24 Gag protein and suggest that cytolytic activity may be a component of the antiviral effect of these cells," Rosenberg and coauthors concluded.
The corresponding author for this report is Eric S. Rosenberg, Massachusetts General Hospital, GRJ 504, 55 Fruit St., Boston, MA 02114, USA.
Key points reported in this study include:
This article was prepared by AIDS Weekly editors from staff and other reports.
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