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Thymic Function
New evidence suggests that hGH also may enhance immune system restoration and HIV-specific T cell responses. At the XIV International AIDS Conference in Barcelona, Spain, this past summer, researchers from Chelsea and Westminster Hospital presented data showing a direct effect of hGH on thymic function in a very small group of people with chronic HIV infection taking antiretroviral therapy. The thymus, a lymphoid organ located behind the upper breastbone, is the site of T cell maturation and differentiation -- that is, where these white blood cells learn to recognize antigens (substances that stimulate an immune system response).
After 12 weeks of hGH administration (4 mg per day), 11 of 12 subjects in this study showed significant increases in naive CD4 and CD8 cell counts, indicating boosted thymic activity. Naive T cells are necessary for immune reconstitution, as memory T cells are programmed to target previously encountered antigens and do not respond to new pathogens introduced into the body (for example, those causing certain opportunistic illnesses, or OIs). In addition, HIV-specific memory CD4 and CD8 responses were significantly improved in at least nine of the 12 subjects after 12 weeks of hGH therapy. The memory CD4 response, however, was sustained only in those who continued taking daily hGH (instead of alternate-day or twice-weekly dosing) through week 24.
While these recent data are intriguing, much more study is needed. Even if it proves viable, clinical use of this potential new indication for hGH is likely years away.
By Bob Roehr ,From San Francisco AIDS Foundation
New evidence suggests that hGH also may enhance immune system restoration and HIV-specific T cell responses. At the XIV International AIDS Conference in Barcelona, Spain, this past summer, researchers from Chelsea and Westminster Hospital presented data showing a direct effect of hGH on thymic function in a very small group of people with chronic HIV infection taking antiretroviral therapy. The thymus, a lymphoid organ located behind the upper breastbone, is the site of T cell maturation and differentiation -- that is, where these white blood cells learn to recognize antigens (substances that stimulate an immune system response).
After 12 weeks of hGH administration (4 mg per day), 11 of 12 subjects in this study showed significant increases in naive CD4 and CD8 cell counts, indicating boosted thymic activity. Naive T cells are necessary for immune reconstitution, as memory T cells are programmed to target previously encountered antigens and do not respond to new pathogens introduced into the body (for example, those causing certain opportunistic illnesses, or OIs). In addition, HIV-specific memory CD4 and CD8 responses were significantly improved in at least nine of the 12 subjects after 12 weeks of hGH therapy. The memory CD4 response, however, was sustained only in those who continued taking daily hGH (instead of alternate-day or twice-weekly dosing) through week 24.
While these recent data are intriguing, much more study is needed. Even if it proves viable, clinical use of this potential new indication for hGH is likely years away.
By Bob Roehr ,From San Francisco AIDS Foundation
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