TY - JOUR T1 - Human respiratory syncytial virus infection <em>in vivo</em> and <em>in vitro</em> induces expression of the B cell differentiation factor BAFF JF - European Respiratory Journal JO - Eur Respir J VL - 38 IS - Suppl 55 SP - 1720 AU - Paul McNamara AU - Angela Fonceca AU - Deborah Howarth AU - Ruth Trinick AU - Joanne Cummerson AU - Rosalind Smyth AU - Brian Flanagan Y1 - 2011/09/01 UR - http://erj.ersjournals.com/content/38/Suppl_55/1720.abstract N2 - Background: In RSV disease, innate immune mediators expressed by infected airway epithelial cells are known to strongly influence both early inflammatory responses and the subsequent development of an adaptive immune response. The B lymphocyte differentiation factor, B cell activating factor of the TNF family, BAFF or TNFSF13B, has been shown to be present in autopsy samples from RSV Infected infants (Reed, J.L. et al. JID; 199:1128-38)Aims: To determine if BAFF expression is elevated in the airways of infants with severe RSV Bronchiolitis and if RSV infection of primary Airway epithelial cells in vitro induces BAFF expression.Methods and results: BAFF protein, as measured by ELISA, was elevated in bronchiolar alveolar lavage fluid collected from the lungs of infants with severe RSV infection (n=10, mean 833pg). Non infected control group infants, admitted for elective surgery had lower levels (n=7, mean 12pg, p&lt;0.027). To further confirm these results BAFF mRNA was measured by taqman real-time PCR in bronchial brushings from patients with RSV bronchiolitis (n=5) and healthy infants (n=6). Average BAFF mRNA expression was around 20 fold higher in samples obtained from infected infants (p&lt;0.01). When In vitro cultures of primary airway epithelial cells isolated from healthy children were infected with RSV A2 strain, BAFF mRNA expression was induced 200 fold with maximum expression at 12 hours post infection (n=4, p&lt;0.01). Protein analysis showed expression of up to 170pg BAFF protein at 48 hours post infection.Conclusions: Airway Epithelial cell expression of the B cell differentiation factor BAFF is induced by RSV infection both in vivo and in vitro. ER -