AGE-RELATED DECLINE OF PERFORIN EXPRESSION IN HUMAN CYTOTOXIC T-LYMPHOCYTES AND NATURAL-KILLER-CELLS

In this study a flow cytometric technique for detecting cytoplasmic pe rforin (P) has been used to quantify age-related changes in perforin e xpression in human peripheral blood lymphocytes (PBL). Proportions of P+ lymphocytes increased after birth, but declined rapidly after the a ge of 70 years. This was true for both T cells and CD16(+) and CD56(+) natural killer (NK) cells. Children showed in addition to high levels of perforin positive CD8(+) cells a much higher proportion of CD4(+)P (+) cells than the other age groups. In elderly individuals there was also a highly significant reduction in mean levels of perforin per cel l as compared with all other groups (P<.05 to .001). Adult women had c onsistently higher mean levels of perforin per cell than adult men for all P+ cell phenotypes. Functional tests clearly showed the deficienc y in early spontaneous cytotoxic potential of PBL from elderly persons due to relative P deficiency, which can be corrected by stimulation o f cytolytic cells with target cells and interleukin-2 (IL-2). The defi ciency in cytolytic activity on the contact with target cells may have implications for antiviral and antitumor immunity in elderly persons. (C) 1998 by The American Society of Hematology.