At the end of the immunization protocol, vaccinated animals showed significantly higher numbers of hCD45 + cells in all organs (i.e. spleen, bone marrow (BM) and mesenteric lymph nodes (mLN)) in comparison to mock-injected control mice. Responder HIS mice exhibited higher numbers of human T and B cells in the spleen, as well as T cells in the BM ( Table 2; Table S1 ), suggesting that the vaccination protocol had a positive impact on the accumulation of human B and T cells. Moreover, the mLN isolated from vaccinated HIS mice contained 4 to 5-fold more hCD45 + cells than those of control animals ( Figure 2C ), suggesting that the mLN structure might play a role in eliciting an immune response in the HIS mice.