Although intranasal (IN) immunization induces mucosal immunity, immunopathologic reactions can occur in the lung. To examine immune responses involved in these reactions, we investigated the T helper cell subset (Th1 and Th2) responses after IN immunization with influenza vaccine plus cholera toxin (CT). BALB/c mice were IN immunized with influenza vaccine alone or in combination with CT (0 and 7d). Total RNA was isolated from the lung 3d later. mRNA expression of T helper cytokines (IL-2, IFN-7, IL-4, and IL-5) were examined by relative RT-PCR using the β2MGL as a standard. IL-4 and IL-5 mRNA was increased with antigen alone and in combination with CT. However, there was no increased expression of IL-2 or IFN-γ mRNA after IN immunization with antigen alone. The presence of these Th1 cytokines were only found in lungs of mice given antigen with CT. In comparison, RNAse protection assays demonstrated Th1 and Th2 cytokine mRNA induction after the inclusion of CT. Consistent with the prominant IFN-γ and IL-2 mRNA responses, we found that delayed type hypersensitivity (DTH) responses developed in mice IN immunized with antigen and CT. This was done by measuring ear thickness of mice given ear challenges with influenza antigen or CT-B. These data indicate that IN immunization results in Th2 cell activation which promotes mucosal IgA responses. However, the mucosal adjuvant, CT, enhances Th1 cytokine production, suggesting that the immunopathologic reactions associated with IN immunization may be mediated by Th1 cells.
|State||Published - 20 Mar 1998|