Age-Dependent Regression of M-MSV Tumors in CBA/H Mice: Requirement for a Macrophage-Adherent Cell Population

Abstract

The effects of aging on immune responses in mice are complex and show some remarkable genetic influences (8,12,13,17,20,21,24, 25, 26,28). Certain strains will show profound impairment of both humoral as well as cellular immunity with increasing age, while other strains will have only moderate decline of immune functions (8,12,13,17,20,21,24,25,26,28). With the exception of the autoimmune-susceptible mouse strains which show a precocious decline of T-dependent functions and cell-mediated immunity (17,20,21,24, 25,28) it is accepted that cell-mediated immunity, measured both in vivo and in vitro, shows less impairment than humoral immunity, especially in long-lived non-autoimmune strains (8,12,13,17,20,21, 25). A good example of such a situation is the CBA/H subline, which is long-lived, does not show any detectable signs of “NZB-type” autoimmune disease (21,25), shows normal levels of T-dependent lymphocytes (20,21), shows intact thymus function (24,28) and a remarkable preservation of immune responses, especially cell-mediated immunity, even at advanced age, beyond the 10% survival range (17,21,25).