The effect of aging on host defences. Implications for therapy.

Immunosenescence is a well known physiological phenomenon resulting from reduced efficiency of the immune system in the elderly. It has been studied both in animal models and in humans. In this review attention is focused on T cell responsiveness, since this cell type is both a marker of the immune response and one of the main targets of several drugs. For this latter reason, most studies of the effect of drugs on the immune system have been performed with reference to the effects on T lymphocytes. In the second part of the article experimental data concerning several drugs and drug classes [steroids, calcium antagonists, theophylline, histamine H1- and H2-receptor antagonists, sodium cromoglycate (cromolyn sodium), pirenzepine, rosaprostol, beta 2-mimetics, antibiotics and antibacterials] and immune responsiveness are reviewed. Lastly, the clinical perspectives of pharmacological treatment in aged subjects in relation to immunosenescence are evaluated.