A humanized mouse platform supporting in vivo maturation of human antibody responses

Abstract

Abstract Mice are widely used models for research and drug discovery, yet provide limited predictive value due to their divergence from humans in immune elements and functions. This underscores the need for more faithful models of the in vivo human immune response. To address this shortcoming, we have generated a HuMice platform by grafting NSG KitW-41J mice with fresh human cord blood CD34+ stem cells via intracardiac injection. This yielded up to 98% human CD45+ cell reconstitution within all major lymphoid compartments, including GALT. Human leukocyte development and long-term persistence in CD34+ cell-engrafted HuMice revealed robust T and B cell maturation, leading to emergence of IgM, IgG, IgA and IgE forming cells. B cells from HuMice underwent in vitro CSR and plasma cell differentiation as efficiently as B cells isolated from healthy humans. Once conditioned with our immune potentiation treatment, HuMice supported T-dependent and T-independent antibody responses involving formation of germinal center-like structures, class-switching, somatic hypermutation, as well as plasma cell and memory B cell differentiation, this entailed further maturation of the B cell compartment resulting in high B2/B1 cell ratio. HuMice were amenable to hydrocarbon-induced autoimmunity leading to lupus-like disease and were susceptible to infection by and respond to human pathogens such as vaccinia virus and EBV. Thus, we have devised a novel in vivo HuMice platform, which allows for generation and maturation of human antibody responses to microbial agents and lends itself to in vivo modeling of autoimmunity, thereby offering opportunities for identification of therapeutic targets and vaccine development.