“…RA has several functions that contribute to a potent mucosal IgA response, including facilitating the proliferation and differentiation of immunocompetent cells (Pantazi et al, 2015;Rühl, 2007), amplifying the induction of IgA class switching and imprinting of the gut-homing receptors on T and B cells (Mora & von Andrian, 2009). In addition to CCR9 and its chemokine ligand CCL25 (Lee et al, 2016;Mora et al, 2006;Seo et al, 2014), numerous ligand-activated nuclear receptors, such as the retinoic acid receptor (RAR), retinoid X receptor (RXR), and peroxisome proliferator-activated receptor (PPAR) (Hoag, Nashold, Goverman, & Hayes, 2002;Iwata, Eshima, & Kagechika, 2003;Seo et al, 2014), are involved in the mucosal IgA response induced by RA. Supplementation of maternal mice with β-carotene during pregnancy increased the lactation of IgA antibody-secreting cells (ASC) in the mammary glands (Nishiyama et al, 2011).…”