Lack of correlation between chemokine receptor and T(h)1/T(h)2 cytokine expression by individual memory T cells

Chemokine and chemokine receptor interactions may have important roles in l eukocyte migration to specific immune reaction sites. Recently, it has been reported that CXC chemokine receptor (CXCR) 3 and CC chemokine receptor (C CR) 5 were preferentially expressed on T(h)1 cells, and CCR3 and CCR4 were preferentially expressed on T(h)2 cells. To investigate chemokine receptor expression by T-h subsets in vivo, we analyzed cytokine (IL-2, IL-4 and IFN -gamma) and chemokine receptor (CXCR3, CXCR4, CCR3, CCR4 and CCR5) mRNA exp ression by individual peripheral CD4(+) memory T cells after short-term sti mulation, employing a single-cell RT-PCR method. This ex vivo analysis show s that the frequencies of cells expressing chemokine receptor mRNA were not significantly different between T(h)1 and T(h)2 cells in normal peripheral blood. To assess a potential role of in vivo stimulation, we also analyzed unstimulated rheumatoid arthritis synovial CD4(+) memory T cells. CXCR3, C XCR4, CCR3 and CCR5 expression was detected by individual synovial T cells, but the frequencies of chemokine receptor mRNA were not clearly different between T(h)1 and non-T(h)1 cells defined by expression of IFN-gamma or lym photoxin-a mRNA in all RA patients. These data suggest that chemokine recep tor expression does not identify individual memory T cells producing Th-def ining cytokines and therefore chemokine receptor expression cannot be a mar ker for T(h)1 or T(h)2 cells in vivo.