Absolute peripheral blood lymphocyte count and subsequent mortality of elderly men. The Baltimore Longitudinal Study of Aging.

In this 16-year longitudinal study of 105 healthy elderly men, we analyzed one aspect of immunosenescence--a decline in the absolute number of peripheral blood lymphocytes--with particular reference to its relationship with subsequent mortality. It was found that there was a significantly (P less than .01) lower absolute lymphocyte count (1432 +/- 55/mm3; mean +/- SEM) within three years of death when compared with five years (1719 +/- 89/mm3) or 10 years (1715 +/- 98/mm3) before death. There was no relationship between this decrease in lymphocytes and age at death, smoking status, or prior cardiac illness. Previous cross-sectional studies have yielded conflicting data on age-related decreases in lymphocytes which may have been the result of an unrecognized selection process that either eliminated or included subjects who were close to death.