In vivo stability of human chemokine and chemokine receptor expression.

Cross-sectional analyses of human PBMC, plasma, and tissue have reported altered chemokine and/or chemokine receptor expression in several inflammatory diseases. Interpretation of such studies is difficult without data on the in vivo stability of such parameters. Using four color flow cytometry, we longitudinally followed CXCR3, CCR5 (Th1-associated), and CCR3 (Th2-associated) expression within CD4+/CD45RO+ and CD8+/CD45RO+ T cell populations in peripheral blood of healthy individuals over a 21 day period. In parallel, we quantified plasma levels of IP-10, Mig, eotaxin and TARC. Chemokine and receptor expression differed markedly between subjects but was highly stable, varying by <5% within individuals. Differences in chemokine receptor expression between subjects were markedly altered when quantified as absolute cell numbers rather than frequencies. Finally, CCR3 expression by CD4+/CD45RO+ T cells was positively correlated with plasma levels of its ligand, eotaxin, whereas strong negative correlations were evident between CXCR3 expression and IP-10 or Mig. These data demonstrate longitudinal stability of chemokine receptor and ligand expression among healthy individuals; reveal that both frequency and absolute cell count analysis is essential for accurate assessment of chemokine receptor expression; and identify inverse relationships between type 1 and type 2 immunity-associated receptors and their ligands in vivo.