Seasonal dynamics of chemokine receptors and CD62L in subjects with asymptomatic skin sensitization to birch and grass pollen

Background: Asymptomatic skin sensitization (AS) has been shown to be a risk factor for respiratory allergic disease. CCR4, CXCR1 and CD62L have all been assigned a role in the immunopathogenesis of allergy. Memory T-cell expression of CCR4, CXCR1 and CD62L has not hitherto been investigated in subjects with AS. Methods: We investigated seasonal CD4 memory T-cell expression of the chemokine receptors CCR4, CXCR1 as well as L-selectin (CD62L) in fresh cultures derived from symptomatic atopics (SAs), subjects with AS and healthy controls (HCs). Peripheral blood mononuclear cells from all three groups were isolated during birch and grass pollination as well as in the following winter. CD4 memory T-cell expression of CCR4, CXCR1 and CD62L was determined by flow-cytometry. Results: During spring and summer, a significantly increased proportion of memory T cells expressed CCR4, CXCR1 and CD62L in SAs when compared with subjects with AS and HCs. Only SAs exhibited seasonal fluctuations in numbers of CCR4, CXCR1 and CD62L positive memory T cells. Conclusion: Although clearly IgE sensitized, subjects with AS have significant diminished numbers of CCR4, CXCR1 and CD62L positive memory T cells, during pollination, when compared with SAs. In contrast to SAs, cultures derived from subjects with AS did not display seasonal variation. Our findings explain the lack of clinical symptoms, during pollination, in subjects with AS.