The thymus atrophies as age progresses. Does the T cell selection (which happens in the thymus) continue to take place? This doubt came into my mind because in the cadaver we dissected, the thymus was hardly more than scanty fibrous tissue. This definitely should have some effect on immune tolerance right? Is this the reason why the elderly are more prone to autoimmune diseases?
Or is it that selection happens only in children? This line of thought would pose a problem since T-cells are short lived and they continuously need to be produced. Or is it that the site of selection is shifted to some other place?
P.S. I am asking these questions assuming that selection is necessary every time new T cells are made. Correct me if this primary assumption is wrong.