Maybe this article will help us all dealing with AA someday! It explains the relationships T cells and thymocytes extremely well. Although it fails to mention that thymocytes also form in the tonsils.
http://www.sciencedaily.com/releases...0930144256.htm
"Demetriou and the others found that the delicate balance determining the proper reactive ability is controlled by glycosylation, a process in which a sugar attaches to a target protein to give the protein stability and form. They saw that changes in the addition of sugars to receptors -- including the blocking of glycosylation -- during T cell development profoundly influenced how thymocytes reacted to the MHC-bound antigens and whether they became mature T cells.
Glycosylation also may help explain the creation of self-reactive T cells that escape from the thymus and can go on to attack the body's own antigens, a process called autoimmunity that's the basis of immune system disorders such as multiple sclerosis."