ENRICHMENT FOR TH1 CELLS IN THE MEL-14(-CELL FRACTION IN AGED MICE() CD4(+) T)

CD4(+) T cells from young and aged mice were sorted into Mel-14(+) cel ls which are regarded as naive cells and Mel-14(-) cells which are reg arded as memory cells. These subsets were stimulated in short-time cul tures with anti-CDS or anti-CD3/anti-CD28 in order to determine the pr esence of Th1 and/or Th2 cytokines. Based on the simultaneous producti on of IL-2, IL-4, IL-10, and IFN-gamma upon anti-CD3 stimulation by Me l-14(-) cells from young and aged mice, it is concluded that this cell population comprises Th1, Th2, and/or Th0 cells. Mel-14(+) cells from young mice only secrete substantial amounts of IL-2 in the presence o f anti-CD28 as a costimulatory signal and can therefore be regarded as Th precursor cells. By contrast, Mel-14(+) cells from aged mice respo nded to anti-CD3 alone, not only by the production of IL-2 but also by the production of high amounts of IFN-gamma and minute amounts of IL- 4 and IL-10, suggesting that these ''naive'' cells in aged mice are en riched for Th1 cells. This was not due to lack of CD28 triggering sinc e anti-CD28 enhanced IFN-gamma as well as IL-4 and IL-10 to a similar extent. Our data therefore indicate that Mel-14 is not exclusively exp ressed on naive CD4(+) T cells. (C) 1995 Academic Press, Inc.