Parenteral Vaccination With a Tuberculosis Subunit Vaccine in Presence of Retinoic Acid Provides Early but Transient Protection to M. Tuberculosis Infection

Discussion Safe and effective mucosal adjuvants to be delivered with purified recombinant proteins or pathogen' subunits are not yet available. Here, we investigated the ability of RA to modulate antigen-specific induced immune responses at mucosal sites. We hypothesized that this vaccine strategy could induce mucosal immune responses in the absence of mucosal delivery by using commercially available systemic adjuvants. Few substances have been demonstrated to be effective as mucosal adjuvants in experimental animal model, which include cholera toxin (CT) and the Escherichia coli heat-labile enterotoxin (LT) (2, 11, 12, 29). However, because of the toxicity of CT, LT and of their derivatives and because of the side effects reported after intranasal delivery of an LT mutant, the clinical use of these molecules is not recommended (8–10). Here, we found that parenteral vaccination with CAF01+H56 in presence of RA induces mucosal H56-specific IgA responses and an enhanced percentage of Ag-specific CD4+ T lymphocytes homing to the lungs. CAF01 is a systemic adjuvant, which is able to shape the immune response toward Th1 and Th17 cells when delivered with different types of Ag (30–33), but unless CAF01 and Ag are delivered through mucosal route following parenteral immunization or given by simultaneous subcutaneous and nasal immunization, it does not induce strong mucosal immunization (34, 35). Therefore, by using RA in combination with CAF01 or wit...
Source: Frontiers in Immunology - Category: Allergy & Immunology Source Type: research