Our results demonstrate that LTβR signaling in adulthood is critical for the maintenance of spleen, lymph nodes, gut-associated lymphoid organs; homeostasis of neutrophils, NK and iNKT cells; and specific IgA antibody responses against mucosal pathogen Citrobacter rodentium; but is dispensable for the maintenance of polyclonal IgA production and autoimmunity. Here, CD79A is linked to Autoimmunity.