T lymphocytes from the normal human peritoneum contain high frequencies of Th2‐type CD8+ T cells

The majority of peritoneal T lymphocytes have been shown to be CD8+ and to co‐express CDw60. Expression of CDw60 characterizes CD8 T cells capable of secreting interleukin (IL)‐4 and supporting IgG production by B cells. We analyzed at the clonal level the functional cytokine profile of CD8+ T lymphocytes from the normal human peritoneum. While the majority of the clones produced interferon (IFN)‐γ and exhibited high alloantigen‐specific cytolytic activity, some clones secreted IL‐4 and IL‐5 but no detectable IFN‐γ. These Th2‐type CD8+ T cell clones provided substantial B cell help for IgG and IgA synthesis and exhibited reduced cytolytic activity. Our results suggest that distinct subsets of CD8+ T cell may occur in different immune compartments.