Immunosenescence: a review

Aging involves the morphological and functional integrity of all organs, in cluding the cellular and humoral immunological functions. The main alterati ons can be listed as follows: (i) Thymic involution resulting in the decrea sed number of lymphoid precursor T- and B-cells. (ii) Reduced proliferative capacity of T-cells; loss of lymphocyte subgroups as a consequence of the shortening of telomeres. (iii) Qualitative deficiency of B-lymphocytes with a reduced response to exogenous antigen!;. (iv) Compromised activity of th e accessory cells, both directly by depressing the chemotactic and phagocyt ic responses, and indirectly by increasing the prostaglandin production whi ch inhibit the proliferation of T-cells. (v) Alterations in the production and secretion of various cytokines. (vi) Other factors like the general phy siological conditions, the nutritional state, psychological habit and vario us hormone levels. (C) 2001 Elsevier Science Ireland Ltd. All rights reserv ed.