TURNOVER OF NAIVE-PHENOTYPE AND MEMORY-PHENOTYPE T-CELLS

On the basis of their surface markers, T lymphocytes are divided into subsets of ''naive'' and ''memory cells'' We have defined the interrel ationship and relative life spans of naive and memory T cells by exami ning the surface markers on murine T cells incorporating bromodeoxyuri dine, a DNA precursor, given in the drinking water. Three findings are reported. First, using a new method we show that the release of newly formed naive T cells from the unmanipulated thymus is very low (confi rming the findings of others with surgical approaches). Second, in thy mectomized mice, T cells with a naive phenotype remain in interphase f or prolonged periods; however, some of these cells divide and retain ( or regain) their ''naive'' markers. Third, most T cells with a memory phenotype divide rapidly, but others remain in interphase for many wee ks. Collectively, the data indicate that long-lived T cells have multi ple phenotypes and contain a mixture of memory cells, naive (virgin) c ells, and memory cells masquerading as naive cells.