engleski

Linking innate to acquired immunity in respiratory syncytial virus infection in children: the role of Toll-like receptor 4 (TLR4)

Cells of the innate immune system recognize structural components of microorganisms by members of the Toll-like receptors (TLR) family. These recognition events alert the immune system to the presence of pathogens and provide information regarding the nature of the invading microorganisms that helps the establishment of acquired immunity. Recently, it has been shown that fusion (F) protein of an important respiratory pathogen, respiratory syncytial virus (RSV), stimulate innate immunity through CD14 and TLR4. Binding of F protein to CD14 and TLR4 induces potent cytokine production by monocytes, and this effect was absent in cells from mice lacking these molecules. In the present study, we analyzed expression of TLR4 on T cells (CD4+ and CD8+), B cells (CD19+) and monocytes (CD14+) in peripheral blood of infants aged 2-5 months (n=28) during the acute phase of RSV infection and 4-6 weeks later. In addition, intracellular expression of TNF-alpha in LPS-stimulated monocytes was determined (n=5). Expression of TLR4 on peripheral blood lymphocytes was very low in all infants, including age and gender-matched control group (n=4) who were hospitalized for minor surgery. However, a transient upregulation of TLR4 expression on peripheral blood monocytes was observed in 8 infants during acute phase of RSV infection. The role of TLR4 in the establishment and resolution of RSV infection and inflammation will be discussed.

immunity; respiratory syncytial virus; infection; children; Toll-like receptor 4 (TLR4)

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