Age-related changes in the relative numbers of Thy-1- and Lyt-2-bearing peripheral blood lymphocytes in mice: a longitudinal approach.

Longitudinal and cross-sectional analyses of Lyt-2+ and Thy-1+ cell populations in the peripheral blood of aging male CBA and C57BL mice revealed that the relative number of Thy-1+, Lyt-2+ cells in the peripheral blood of both mouse strains remained relatively constant during the entire lifespan. The proportion of Thy-1+, Lyt-2- cells decreases with age, which indicates that major changes in the T-cell compartment with age must be attributed to the Lyt-2- helper compartment. For individual CBA mice, a direct relation between the relative number of Thy-1+, Lyt-2- cells at a certain age and the time remaining to live is demonstrated. The changes in the proportion of Lyt-2+ of total Thy-1+ cells in CBA mice show a regular pattern of slow increase with age followed by a rapid increase phase preceding the death of the animal. In C57BL mice, the development of the proportion of Lyt-2+ T cells with age showed various patterns. Rapid changes both positive and negative in these mice seem to be indicative of approaching death. The predictive value of Lyt-2+/Thy-1+ ratios at a given age for the remaining lifespan of individual mice is discussed.