Senescent loss of resistance to murine sarcoma virus (Moloney) in the mouse.

Abstract

Summary Sensitivity to the induction of sarcomas following the injection of the Moloney strain of murine sarcoma virus (MSV-M) has been studied in BALB/c × DBA/2 F 1 mice between birth and extreme old age (3 years). In accord with previously published information, we have demonstrated loss of sensitivity, which is at a maximum in newborns, by the time young adulthood is attained. However, sensitivity reappears by 1 year of age and becomes progressively more severe with advancing age. At the oldest ages tested, 2.5 to 3 years, BALB/c × DBA/2 F 1 mice are as sensitive as newborns, i.e. , 100% develop progressively growing tumors. This age-dependent sensitivity was reflected by the development of specific neutralizing antibody. The resistant young adults developed a serum antibody which reacted specifically with the virus and which was able to neutralize the oncogenic effects of the MSV-M. Following MSV-M injection, the sensitive newborn and aged mice did not develop this antibody in sufficient concentration to be detected by our tests, nor did mice of any age that were not virus-injected demonstrate this antibody. We propose, therefore, that the age-dependent reappearance of sensitivity to MSV-M results from a similar age-dependent decay of humoral immune capacity.