PRESENCE OF LIFE-SHORTENING FACTORS IN SPLEENS OF AGED MICE OF LONG LIFESPAN AND EXTENSION OF LIFE EXPECTANCY BY SPLENECTOMY

Spleen cells of aged (C57BL/6 × C3H)F1 mice, when transferred into middle-aged mice of the same strain, severely reduced the survival of the recipients. This life-shortening effect became progressively greater with increasing age of the donor mice. In contrast, splenectomy of mice of interjacent ages sustained life; under our experimental conditions it nearly doubled the remaining life expectancy. Although the influence of the spleen on survival remains to be explained, the action of the age-related spleen factors on progenitor cells may cause the steady decline in immunologic capacity with advancing age (previously reported). © 1969.