Interferon gamma (IFN-γ) plays an important role in the antiviral immune response during respiratory syncytial virus (RSV) infections. Monocytes and T cells are recruited to the site of RSV infection, but it is unclear whether cell-cell interactions between monocytes and T cells regulate IFN-γ production. In this study, micro-array data identified the upregulation of sialic acid-binding immunoglobulin-type lectin 1 (Siglec-1) in human RSV-infected infants. In vitro, RSV increased expression of Siglec-1 on healthy newborn and adult monocytes. RSV-induced Siglec-1 on monocytes inhibited IFN-γ production by adult CD4+ T cells. In contrast, IFN-γ production by RSV in newborns was not affected by Siglec-1. The ligand for Siglec-1, CD43, is highly expressed on adult CD4+ T cells compared to newborns. Our data show that Siglec-1 reduces IFN-γ release by adult T cells possibly by binding to the highly expressed CD43. The Siglec-1-dependent inhibition of IFN-γ in adults and the low expression of CD43 on newborn T cells provides a better understanding of the immune response against RSV in early life and adulthood.

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European Journal of Immunology
Erasmus MC: University Medical Center Rotterdam

Jans, J. (Jop), Unger, W.W. (Wendy W.J.), Vissers, M. (Marloes), Ahout, I.M. (Inge M.L.), Schreurs, I. (Inge), Wickenhagen, A. (Arthur), … Ferwerda, G. (2018). Siglec-1 inhibits RSV-induced interferon gamma production by adult T cells in contrast to newborn T cells. European Journal of Immunology. doi:10.1002/eji.201747161