Downregulation of CXCR6 and CXCR3 in Lymphocytes from Birch-allergic Patients

Preferential expression of chemokine receptors on Th1 or Th2 T-helper cells has mostly been studied in cell lines generated in vitro or in animal models; however, results are less well characterized in humans. We determined T-cell responses through chemokine receptor expression on lymphocytes, and cytokine secretion in plasma from birch-allergic and healthy subjects. The expression of CCR2, CCR3, CCR4, CCR5, CCR7, CXCR3, CXCR4, CXCR6, IL-12 and IL-18R receptors was studied on CD4⁺ and CD8⁺ cells from birch-allergic (n = 14) and healthy (n = 14) subjects by flow cytometry. The concentration of IL-4, IL-5, IL-10, IL-12, IFN-γ and TNF-α cytokines was measured in plasma from the same individuals using a cytometric bead array human cytokines kit. The similar expression of CCR4 in T cells from atopic and healthy individuals argues against the use of the receptor as an in vivo marker of Th2 immune responses. Reduced percentages of CD4⁺ cells expressing IL-18R, CXCR6 and CXCR3 were found in the same group of samples. TNF-α, IFN-γ, IL-10, IL-5, IL-4 and IL-12 cytokines were elevated in samples from allergic individuals. Reduced expression of Th1-associated chemokine receptors together with higher levels of Th1, Th2 and anti-inflammatory cytokines in samples from allergic patients indicate that immune responses in peripheral blood in atopic diseases are complex and cannot be simplified to the Th1/Th2 paradigm. Not only the clinical picture of atopic diseases but also the clinical state at different time points of the disease might influence the results of studies including immunological markers associated with Th1- or Th2-type immune responses.