Wolf, Amaya I.

Abstract Respiratory infection with influenza virus (flu) induces long-lasting protective humoral immunity. Although flu-specific antibody secreting cells (ASCs) increase post infection (p.i.) and are present in various organs, including the lung, it is unclear what signals promote their maintenance and/or survival. We determined that flu-specific ASCs were maintained in the lung up to half a year p.i.. These cells were not proliferating as they failed to incorporate BrDU. With the hypothesis that BLyS-family members may be important for ASC maintenance, we investigated the B cell response to flu in TACI-/- mice. TACI has been implicated in the T-independent type II response, but its role in anti-viral immunity is unknown. WT and TACI-/- mice exhibited a similar anti-flu B cell response at day 8 p.i., however, by day 33p.i., TACI-/- mice had significantly lower anti-flu antibody levels in the serum and locally in the lung. TACI deficiency did not affect flu-specific ASC numbers in spleen and lung-draining mediastinal lymph nodes. In contrast, it resulted in drastically reduced ASCs in lung and bone marrow. The results of our study will be discussed in the context of protection and possible implications for vaccine development.