Mucosal and systemic immune response to sublingual or intranasal immunization with phosphorylcholine

Abstract Objective Phosphorylcholine (PC) is a structural component of a wide variety of pathogens including Streptococcus pneumoniae and Haemophilus influenzae . Here, the immune response in mice to PC immunization via the sublingual (SL) route versus the intranasal (IN) route was investigated in terms of efficacy and safety. Methods BALB/c mice were immunized with PC-keyhole limpet hemocyanin (KLH) plus cholera toxin (CT) or CT alone via the IN or SL route. The immune response generated was studied in terms of PC-specific antibody titers, interferon (IFN)-γ and interleukin (IL)-4 production by CD4+ T cells, and cross-reactivity of PC-specific immunoglobulin (Ig)-A antibodies in nasal washes against S. pneumoniae and non-typeable H. influenzae. Results SL and IN immunization with PC-KLH plus CT resulted in a marked increase in the levels of PC-specific, mucosal IgA and serum IgM, IgG, and IgA antibodies. Additionally, SL immunization elicited significantly higher levels of PC-specific IgG2a subclass antibodies and IFN-γ in serum. On the other hand, IN immunization with CT alone remarkably increased the total IgE level in serum compared with SL and IN immunization with PC-KLH plus CT. PC-specific IgA antibodies in nasal wash samples reacted to most strains of S. pneumoniae and non-typeable H. influenzae. Conclusion SL immunization is as effective as IN immunization to induce PC-specific immune responses and more effective than IN immunization to reduce the production of IgE and to prevent the sensitization to allergen causing type I allergy.