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July 11, 2006
Thymic Volume Predicts T-cell Drop After HIV Treatment Interruption (Reuters Health)
Tuesday July 11, 2006 (Reuters Health) - Assessment of the thymic volume with mediastinal CT is useful in predicting the drop in CD4+ T cells seen in HIV-infected adults during treatment interruption, according to a report in the June issue of the Journal of Acquired Immune Deficiency Syndromes.
Measurement of thymic volume "could be a useful tool to select patients who would be good candidates for prolonged highly active antiretroviral therapy (HAART) interruption," senior author Dr. Manuel Leal, from the Virgen del Rocio University Hospital in Seville, Spain, and colleagues note.
The study involved 39 HIV-infected patients who began a treatment interruption protocol. Before starting the protocol, the subjects had CD4+ cell counts of at least 500 cells/microliter, nadir CD4+ cell counts of at least 250 cells/microliter, and viral loads below 50 copies/mL for the last 12 months or longer. The main endpoint was a drop in the CD4+ cell count below 350 cells/microliter.
Nine patients (23%) achieved the main endpoint, the report indicates.
The only significant predictor of CD4+ cell decline during treatment interruption was the thymic volume (p = 0.04), although the nadir CD4+ cell count came close. With a higher thymic volume, the drop in CD4+ cell counts after halting treatment was less pronounced.
By contrast, age, gender, hepatitis C virus coinfection, baseline CD4+ cell count, T-cell receptor excision circle-bearing cells, and early viral load rebound were not predictive of the main endpoint.
"To our knowledge, this is the first time that thymic volume has been observed to predict CD4+ T-cell loss rates among persons halting HAART," the authors conclude. J Acquir Immune Defic Syndr 2006;42:203-206.
