Distal IgA immunity can be sustained by alphaEbeta7+ B cells in L-selectin-/- mice following oral immunization

Understanding the role of homing receptors could aid vaccine strategies for developing distal mucosal immunity. Infection studies have revealed that immune intestinal B cells use alpha(4)beta(7) homing receptors, but their role in subsequent oral immunization with soluble antigens is unknown. To assess the influence of L-selectin and alpha(4)beta(7) on distal B cells following oral cholera toxin (CT) immunization, L-selectin-deficient (L-Sel(-/-)) IgA anti-CT-B-specific B cells were enhanced 30-, 9.2-, and 3.5-fold in head and neck lymph nodes (HNLNs), nasal-associated lymphoid tissue, and nasal passages (NPs), respectively, vs. L-Sel(+/+) mice. Cell-sorted intestinal and NP IgA antibody-forming cells (AFCs) were mostly alpha(4)beta(7)(+), unlike HNLN L-Sel(-/-) IgA and IgG anti-CT-B AFCs that were alpha(E)beta(7)(+), contrasting with L-Sel(+/+) HNLN IgA AFCs that were mostly alpha(4)beta(7)(+). In vitro studies revealed that L-Sel(-/-) HNLN B cells preferentially expressed alpha(E) following polyclonal stimulation. These studies show that HNLN B cells express alpha(E)beta(7) in the absence of L-selectin to sustain distal IgA responses.