2.2. Mice and immunizations

DR4-IE transgenic mice on C57Bl/6 background (referred to as DR4tg) lacking endogenous MHC class II molecules were bred in-house [22]. They were compared to wild type C57Bl/6 (B6) (The Jackson Laboratories, Maine, USA). Mice were housed at the Animal Care and Veterinary Services pathogen-free facility at the University of Western Ontario according to the guidelines of the Canadian Council on Animal Care. The study was approved by the Animal Care and Use Committee (The University of Western Ontario, London, ON, Canada). Female and male mice received primary and booster immunization of HomoJED peptide (100 ​μg each time) or PBS control via subcutaneous (sc) route as described by Lac et al. [21].