Gut-homing (α4β7+) Th1 memory responses after inactivated poliovirus immunization in poliovirus orally pre-immunized donors

Mucosal infections are prevented by a specialized local immune system. Immune cells of this compartment can also be found in the blood and are characterized by the expression of mucosa-specific homing molecules. Here, the cellular immune responses after inactivated poliovirus immunization (IPV) in poliovirus orally pre-immunized donors were investigated. Subcutaneous IPV induced a transient increase in the proliferative response against poliovirus antigen and in the number of poliovirus-specific CD4+ T cells in the blood of the vaccinees. These cells were characterized to be of the effector memory type (CD45RA−/CD45RO+/CCR7−/CD27+) and expressed the homing molecule α 4 β 7, indicating their origin from the gut. Together these data show the recurrence of gut-derived poliovirus-specific cells upon IPV and evaluate the whole-blood assay as a powerful tool for monitoring the success of a vaccination.