Expression of L-selectin (CD62L) discriminates Th1- and Th2-like cytokine-producing memory CD4⁺ T cells

Human memory (CD45RO⁺) CD4⁺ T cells can be distinguished into two subpopulations on the basis of expression of the lymph node homing receptor, L-selectin (CD62L). In a prior study we showed that human L-selectin-positive memory T-helper (Th) cells promote the maturation of IgG- and IgA-producing cells by naive B cells. To further elucidate the contribution of memory CD4⁺ T cells to B-cell differentiation, human memory CD4⁺ T cells with or without L-selectin expression were evaluated for production of cytokines that participate in regulation of immunoglobulin production. It was found that L-selectin-positive human memory CD4⁺ T cells produce mainly interleukin (IL)-4 and IL-5, whereas L-selectin-negative CD4⁺ T cells produce mainly interferon-γ (IFN-γ). This profile of cytokine expression coincides with the profile that distinguishes Th1 and Th2 subsets. In contrast to the murine system, IL-10 production was similarly contributed by human L-selectin-positive and -negative memory CD4⁺ T-cell subpopulations. These results suggest that the human L-selectin-negative and -positive subpopulations of human memory CD4⁺ T cells contain Th1-like and Th2-like cytokine-producing cells, respectively.