It is my understanding that HIV can cause permanent damage to the thymus and potentially make it very difficult to restore the human immune system because the thymus (along with bone marrow) is important for T-cell production. This may sound like a stupid question but is there any indication that PWAs experience thymus pain? Would chest pain in the location of the thymus be an indication that HIV is attacking T-cell production in the Thymus? Or could such pain be a sign of simply an overworked thymus gland as a result of HIV depletion of T-cells? If the thymus is damaged, does this mean that HAART will be less effective in increasing CD4 count? Are there tests for measuring thymus activity? I know I have included several questions here, but there isn't very much information out there about this topic.

These are all good questions. One of the themes emerging in the last 18 months is that the thymus is key to immune reconstitution. The basic story is that the older you are, the longer you have been infected, the lower the thymic contribution to rebuilding T cells. This is all relative however, and most people maintain thymic activity until very late in life. It does appear that some people with HIV have much more thymic damage than others. In children, there seems to be a small group that has a totally destroyed thymus, and this goes along with being a rapid progressor. This does not mean that it is the reason they are a rapid progressor, since the damaged thymus could just be a sign of overwhelming disease.

I don't know of any reason to think that people experience pain in the thymus. The effects are very gradual, there are probably no nerves in the thymus, but I guess it could be possible. There are two indirect measures of health of the thymus, and one direct one. The one that is clinically useful is just to look at the speed that the T cells rise after the viral load is suppressed. The average is about 100 cells a year. The other indirect, and expensive, measure is to use a CT scan of the chest to measure the size of the thymus. This is used in research, but is not clinically useful. The new direct measure is by measuring "TREC's" These are T cell receptor excision circles, a chunk of DNA that is a marker that a T cell has recently been modified by the thymus. This is a new and exciting research tool, but not likely to be clinically useful.

Hope this helps. Stay well

Andrew T. Pavia, M.D.