B cell αv integrin regulates germinal center derived lung-resident IgA B cell responses following influenza virus infection.

Emerging studies have highlighted the importance of tissue-resident B cells in the lungs, for protective immunity against respiratory viruses. However, the mechanisms controlling generation and maintenance of such tissue-resident B cells at respiratory sites remain obscure. We have previously shown that αv integrins limit B cell responses to antigens containing Toll-like receptor ligands, and that deletion of B cell αv integrins, in mice, enhances germinal center (GC)-derived long-lived B cell responses after systemic immunization with viral antigens. Here we investigated whether αv also regulates B cell responses at the respiratory tract during viral infection. Our data show that αv integrin restricts tissue-resident B cell responses in the airway, and that deletion of B cell αv promotes generation of lung-resident IgA B cell responses following influenza A virus (IAV) infection. Investigating the mechanism for this, we found that loss of B cell αv, promotes persistence of GC reactions locally in the lungs, which leads to increases in lung-resident IgA+ memory B cells, cross-reactive to antigenic variants. Thus, these studies reveal how IgA B cells are maintained in the lungs and point to a new strategy to improve the durability of lung-resident IgA B cell responses for IAV vaccine efficacy.