[Can T-cell immunity in an adult be regenerated?]

In man, normal peripheral T cell function depends on thymopoiesis during the foetal and perinatal period (up to 3 months). In humans, studies have shown that declines in thymic T-cell regenerative capacity begins relatively early in life, resulting in a limited capacity for T-cell regeneration by young adulthood. These limitations in T-cell regeneration have significant clinical implications in the setting of HIV infection and bone marrow transplantation. Recent studies have reported that the human thymus can generate new cells throughout life, and even late, into adult life. Patients infected with HIV can generate new peripheral T cells after anti-viral therapy. In view of a continuous role of thymopoiesis in man, there is a growing need for relevant models of human thymopoiesis. Using a hybrid human-mouse FTOC model, we have shown that IL-7 is an essential growth factor for thymocytes and that certain genes of HIV interfere with the normal production of thymocytes. These studies allow the selection for products active in therapeutic restoration or maintenance of thymic function.