Immunisation with virion-loaded plasmacytoid or myeloid dendritic cells induces primary Th-1 immune responses.

Dendritic cells (DCs) induce different types of immune responses depending on their lineage and activation signals. When exposed to inactivated pseudorabiesvirus (iPRV), plasmacytoid but not myeloid DCs released IFN-alpha and IL-12. Remarkably, both iPRV-pulsed DC types were able to induce primary IFN-gamma producing T cells and IgG isotype switching in vivo. In contrast, tetanus toxoid pulsed DCs did not induce detectable primary immune responses. The efficacy of antiviral T and B cell priming proved dependent on the recipient's genotype. We conclude that either plasmacytoid or myeloid DCs pulsed with inactivated virus suffice to induce primary Th1-polarised immune responses.