Evaluation of lymphokine-activated killer cell development in young and old healthy humans

The kinetics of the development of lymphokine-activated killer (LAK) cell activity, the surface phenotype, and the expression of p55 and p75 interleukin 2 receptors (IL-2R) on IL-2-activated peripheral lymphocytes have been investigated in young and old healthy humans selected according to the Senieur Protocol criteria. No difference is present between young and old healthy subjects in terms of LAK cell activity development. The proliferative capacity of lymphocytes incubated with IL-2 shows similar kinetics in young and old subjects. The mean percentages of CD56+ and CDl6+ cells reach higher levels in old than in young donors. The proportion of CD56+/CD25+ cells in culture is significantly higher in old than in young individuals. A progressive decrease of CD4+ population occurs during LAK cell development, both in young and old subjects. The proportion of CD4+ T cells in culture is lower in old than in young individuals. No age-related difference is present in the mean percentage of cells positive for p55 or p75 IL-2R at any culture time. Thus, our findings show similar kinetics of development of LAK cell activity in young and old subjects, indicating that aging per se does not represent an exclusion criterion of cancer patients from clinical trials of adoptive immunotherapy. A higher proportion of CD56+ and CDl6+ cells seems to be required in old subjects to obtain the same levels of LAK cell activity present in young age.