Immune system reactivated in HIV adults

Washington, Feb 23 (UNI) There is now a ray of hope for HIV-infected adults as American scientists have found therapies that stimulate the thymus can be used to revitalise the production of vital immune cells, called 'T- cells'.

''HIV disease destroys T-cells, leading to collapse of the immune system and severe infection. The thymus gland, which produces T-cells, gradually loses function over time (a process called 'involution') and becomes mostly inactive during adulthood,'' said Laura Napolitano, MD, lead author of the study.

''Because the gland does not function well in adults, it is difficult for HIV-infected adults to make new T-cells. Thus, thymus-stimulating therapies could help HIV-infected patients to rebuild their embattled immune systems,'' the researcher told Sciencedaily.

The study conducted by the Gladstone Institute of Virology and Immunology and the University of California, San Francisco (UCSF) showed that thymus could be stimulated to produce more T-cells, which was earlier thought that it could not be reactivated in humans.

''These results represent new proof-of-principle findings that thymic involution can be reversed in humans'' said Ms Napolitano, an Assistant Investigator at Gladstone and Assistant Professor of Medicine at UCSF.

''These findings contribute new information to our understanding of T-cell production and are also an important step to determine whether immune therapies might someday benefit patients who need more T-cells,'' she added.

''The findings of this study are exciting,'' said senior author Joseph M McCune, a Professor of Medicine at UCSF. ''If these findings bear out in larger studies, this news should be of particular interest to those in need of new T-cells, for instance, adults with HIV disease or other forms of T cell depletion,'' he added.

However, both Napolitano and McCune cautioned, ''More research is needed to learn whether stimulating the production of new T-cells actually provides a health benefit.

''We have shown an increase in the quantity of T-cells, but must also determine whether a recovered thymus produces good quality T-cells that provide satisfactory immune protection,'' Ms Napolitano said, adding, ''This was a relatively small study of carefully selected adults receiving effective therapy for HIV infection and our findings may not apply to the majority of individuals.'' While the sample in this study was relatively small, Ms Napolitano said a larger, multi-center study conducted by the AIDS Clinical Trial Group (ACTG) had yielded similar results in preliminary analyses and was expected to report these results in the future.

''The ACTG study will provide additional data that will add to our understanding of GH effects on the immune system,'' said Ms Napolitano who is also a member of the ACTG Team conducting the multi-center study.

''GH is a protein hormone that acts upon most T-cells of the body, which can result in several side effects,'' informed Ms Napolitano.

''We are interested in learning the specific way that GH affects the thymus so that therapy can be more narrowly directed to the thymus,'' she concluded .

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