Human B-cell ontogeny in humanized NOD/SCID γc null mice generates a diverse yet auto/poly-and HIV-1-reactive antibody repertoire

摘要

Characterization of the human antibody (Ab) repertoire in mouse models of the human immune system is essential to establish their relevance in translational studies. Single human B cells were sorted from bone marrow and periphery of humanized NOD/SCID γc null (hNSG) mice at 8-10 months post engraftment with human cord blood-derived CD34+ stem cells. Human IG variable heavy (V H) and kappa (V κ) genes were amplified, cognate V H-V κ gene-pairs assembled as single-chain variable fragment-Fc Abs (scFvFcs) and functional studies were performed. Although overall distribution of V H genes approximated the normal human Ab repertoire, analysis of the V H-third complementarity-determining regions in the mature B-cell subset demonstrated an increase in length and positive charges, suggesting autoimmune characteristics. Additionally, 70% of V κ sequences utilized V κ 4-1, a germline gene associated with autoimmunity. The mature B-cell subset-derived scFvFcs displayed the highest frequency of autoreactivity and polyspecificity, suggesting defects in checkpoint control mechanisms. Furthermore, these scFvFcs demonstrated binding to recombinant HIV envelope corroborating previous observations of poly/autoreactivity in anti-HIVgp140 Abs. These data lend support to the hypothesis that anti-HIV broadly neutralizing antibodies may be derived from auto/polyspecific Abs that escaped immune elimination and that the hNSG mouse could provide a new experimental platform for studying the origin of anti-HIV-neutralizing Ab responses.