Age and immunity
Longitudinal studies are defining progressive alterations to the immune system associated with increased mortality in the very elderly. Many of these changes are exacerbated by or even caused by chronic T cell stimulation by persistent antigen, particular

Progesterone shows promise as treatment for traumatic brain injuries
Researchers have found that giving progesterone to trauma victims shortly following brain injury appears to be safe and may reduce the risk of death and the degree of disability.