Expression of chemokine receptor CX3CR1 in infants with respiratory syncytial virus bronchiolitis


Alenka Gagro, Institute of Immunology, Rockefellerova 10, HR-10000 Zagreb, Croatia.
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Respiratory syncytial virus (RSV) glycoprotein G mimics fractalkine, a CX3C chemokine, which mediates chemotaxis of leukocytes expressing its receptor, CX3CR1. The aim of this study was to examine the relationship between RSV infection and expression of perforin and IFN-γ in CX3CR1-expressing peripheral blood CD8+ T cells. Samples were collected from infants with RSV bronchiolitis, both in the acute and convalescence phase (n = 12), and from their age- and sex-matched healthy controls (n = 15). Perforin expression and IFN-γ secretion in CX3CR1+ CD8+ T cells were assessed by four-color flow cytometry. The NF-κB p50 and p65 subunit levels were also determined as markers of RSV-induced inflammation. Study results showed perforin and CX3CR1 expression to be significantly lower in the convalescent phase of infected infants than in healthy controls. There was no significant difference in IFN-γ secretion and NF-κB binding activity between two time-points in RSV-infected infants, or when compared with healthy controls. Infants with prolonged wheezing had lower acute-phase CX3CR1 levels in peripheral blood. These data indicate existence of an event persisting after acute RSV infection that is able to modulate effector functions of cytotoxic T cells, and also link disease severity with CX3CR1 expression.