RESEARCH Default in plasma and inte,3,

Full list of author information is available at the end of the articleThe gastrointestinal tract is a privileged site for both HIV-1/SIV replication and extensive CD4+ T-cell depletion at all stages of the pathogenic infection [1,2]. One of the physiological roles of the gastrointestinal tract in immuno-logical defense is to produce large amounts of IgA that contribute to the protection of the intestinal mucosa from (plasma cell precursors) generated in germinal centers (GC) of Peyer’s patches (PP) and mesenteric lymph nodes that constitute major inductive sites of T-dependent IgA antibodies. Both T-cell help and local production of cyto-kines participate in T-dependent IgA production [4-7]. IgA class switching also occurs in isolated lymphoid folli-cles (ILF), which have a cellular composition similar to PP-associated follicles and constitute dynamic lymphoid structures that develop in response to chronic infection or inflammation [8-10]. In addition to the canonical TGFβ