The role of a thymus-pineal axis in an immune mechanism of aging.

The Immune Theory of Aging cannot explain the cause of immune decline. It is hypothesized that the pineal gland acting in utero and during neonatal life in altricial mammals serves as a component of the immune system. Evidence in support of the presence of a thymus-pineal axis is presented. It is postulated that the pineal gland carries a considerable burden of immunological defense during maturation of the thymus, and also acts in the programming of the immune system. By relating thymus and immune function to the pineal and its known role as a neuroendocrine transducer for the entrainment and control of biorhythms, a consilence is developed between the role of the immune system in senescence and the pineal function in biorhythmicity. The relationships developed thus permit an extension of the immune theory as regards causative mechanisms.