Abstract
Abstract
Life span appears to be under genetic control. Genes linked to the major histocompatibility complex are associated with life span. These genes also play a major role in regulating immune reactivity and suggest that immunological factors may be determinants in the length of life. Many of the immune functions which change with age can be related to the involution of the thymus gland and the decline in thymic hormone levels. Impaired proliferation of T cells from old individuals may be the cellular basis of certain changes in immunological reactivity seen with age. Lymphocytes like arterial smooth muscle cells and fibroblasts from elderly donors appear to have an impaired capacity to proliferate in culture.
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