Abstract: The thymus progressively involutes with age, particularly from puberty when sex steroids increase in production, with the gradual loss of newly produced naive T cells resulting in a restricted T cell receptor repertoire, skewed towards memory cells. This translates to a striking reduction in immune responsiveness and an obvious delay in immune reconstitution. Regeneration of the thymus is fundamental to developing new strategies for the clinical treatment of many diseases of immunological origin. Currently the use of sex steroid inhibitors, GH, KGF and IL-7 represent the first candidates in thymus-based therapies, as well as the function of Ghrelin for thymic regeneration is coming to attention.

Key words: thymus; aging; regeneration; sex steroids; KGF; IL-7