The extrafollicular (EF) B cell response generates virus-specific IgM, IgG and IgA in the airway lumen and local lymph nodes as early as 72h after influenza virus infection, correlating temporally with virus clearance. EF responses are distinct in kinetics, function and signaling requirements from the slower germinal center responses. EF B cell responses habe been largely dismissed as significant in pathogen-induced immunity, as they are though to generate only short-lived plasma cells and low affinity antibodies.
