Mucosally activated circulating human B cells in diarrhea express homing receptors directing them back to the gut

BACKGROUND & AIMS: Recirculation of mucosal lymphocytes has been established in animals but not in humans. Specific antibody-secreting cells in the blood of patients with diarrhea, initially activated in gut mucosa, are potential recirculating cells. The aim of this study was to determine whether these cells circulate back to gut by analyzing their homing receptors. METHODS: Blood mononuclear cells, separated with immunomagnetic cell sorting into receptor-positive and receptor- negative populations, were assayed for pathogen-specific antibody- secreting cells and all immunoglobulin-secreting cells using enzyme- linked immunospot assay. RESULTS: The gut mucosa homing receptor alpha4beta7 was expressed more frequently on pathogen-specific antibody- secreting cells than on immunoglobulin-secreting cells of healthy controls (P