The CC-chemokine receptor 5 (CCR5) is a marker of, but not essential for the development of human Th1 cells

The CC-chemokine receptor 5 (CCR5) has recently been described as a surface marker of human T cells producing type 1 (Th1) cyto- kines. Here we confir m that CCR5 is expressed on human Th1 but not on Th2 T-cell clones. Using i ntracellular cytokine staining, we show that alloantigen specific CD4(+) T- cell lines derived from a CCR5-deficient. individual (Delta 32 allele homoz ygote) contain high numbers of both interferon gamma (IFN-gamma) and interl eukin (IL)-2 producing cells, low numbers of IL-10 producing cells and no I L-4 or IL-5 producing cells when stimulated with phorbol ester and ionomyci n in vitro. These results were similar to those obtained from allo-antigen specific CD4(+) T-cell lines derived from CCR5 expressing individuals An en zyme-linked immunoabsorbent assay (ELISA) confirmed that the Th1 cytokine-p ositive cells from the CCR5-deficient individual were able to produce equal amounts of cytokines when compared to T-cell lines from CCR5-expressing in dividuals These results demonstrate that CCR5-negative T cells display the same capacity of Th1 T-cell differentiation as T cells derived h-om CCR5-ex pressing individuals Thus, CCR5 expression is not essential for differentia tion of human Th1 T cells.