The kinetics and regulation of Stra6 expression in spleen and antibody production in tetanus toxoid‐immunized mice

Coadministration of retinoic acid (RA) and poly‐I:C (PIC) has been shown to cooperatively enhance the anti‐tetanus toxoid (TT) vaccine response in adult mice. The germinal center (GC) formation in spleen is critical for antibody response. Recent studies have identified Stimulated by Retinoic Acid‐6 (Stra6) as the cell membrane receptor for RBP‐retinol in many organs, including spleen. The objectives of the present studies were to test whether retinoids and/or PIC could regulate the kinetics and magnitude of Stra6 expression in mouse spleen and antibody production. Eight‐week‐old C57BL/6 mice were immunized with TT. In the kinetic study, VA treatment increased anti‐TT IgM and IgG production as well as splenic Stra6 expression and altered the developing patterns of antibody production and Stra6 expression. In treatment studies, retinoids and PIC were effective in significantly increasing anti‐TT IgM and IgG levels and splenic Stra6 mRNA expression ( P <0.05). Treatment combinations with PIC dramatically augmented plasma anti‐TT IgM and IgG levels ( P <0.05). In conclusion, retinoid treatment, including VA, RA and the VA and RA combination, and the combination of retinoid and PIC stimulated the expression of Stra6 in spleen, which could increase the retinol uptake, and this was consistent with improved immune responses after antigen immunization. Supported by NIH Grant DK41479.