Maximal adjuvant activity of nasally delivered IL-1α requires adjuvant responsive CD11c+ cells and does not correlate with adjuvant-induced in vivo cytokine production

摘要

IL-1 has been shown to have strong mucosal adjuvant activities, but little is known about its mechanism of action. We vaccinated IL-1R1 bone marrow chimeric mice to determine if IL-1R1 expression on stromal cells or hematopoietic cells was sufficient for the maximal adjuvant activity of nasally delivered IL-1α as determined by the acute induction of cytokine responses and induction of Bacillus anthracis lethal factor (LF)-specific adaptive immunity. Cytokine and chemokine responses induced by vaccination with IL-1α were predominantly derived from the stromal cell compartment and included G-CSF, IL-6, IL-13, MCP-1, and KC. Nasal vaccination of Il1r1^−/− mice given wild-type bone marrow (WT→KO) and WT→WT mice with LF + IL-1α induced maximal adaptive immune responses, while vaccination of wild-type mice given Il1r1^−/− bone marrow (KO→WT) resulted in significantly decreased production of LF-specific serum IgG, IgG subclasses, lethal toxin-neutralizing antibodies, and mucosal IgA compared to WT→KO and WT→WT mice (p < 0.05). IL-1α adjuvant activity was not dependent upon mast cells. However, the ability of IL-1α to induce serum LF-specific IgG2c and lethal toxin-neutralizing antibodies was significantly impaired in CD11c-Myd88−/− mice when compared to WT mice (p < 0.05). Our results suggest that CD11c+ cells must be directly activated by nasally administered IL-1α for maximal adjuvant activity and that, while stromal cells are required for maximal adjuvant-induced cytokine production, the adjuvant-induced stromal cell cytokine responses are not required for effective induction of adaptive immunity.