Reconstitution of functional human B lymphocytes in NOD/SCID mice engrafted with ex vivo expanded CD34+ cord blood cells

Objective Functional capacity of B cells developed from ex vivo expanded hematopoietic stem cells has not been fully evaluated. Therefore, we investigated the antigen-specific antibody production in human B cells maturated from ex vivo expanded cord blood (CB) CD34+ cells in NOD/Shi-scid (NOD/SCID) mice. Materials and Methods CB CD34+ cells were cultured for 5 days in the presence of human cytokines and the murine stromal cell line HESS-5, and transplanted into irradiated NOD/SCID mice. These mice, reconstituted with human hematopoietic cells, were challenged with T-cell–independent (TI) or T-cell–dependent (TD) antigens after CD19+ cells appeared at 6 weeks. Results Three months later, anti-dinitrophenol (DNP)-specific antibody was detected in both mice immunized with DNP-Ficoll (TI) and those immunized with DNP-keyhole limpet hemocyanin or DNP-ovalbumin (TD). The anti-DNP antibody was mainly immunoglobulin M, but a small amount of immunoglobulin G also was detected. In the spleen, the majority of CD19+ cells expressed mature B-cell markers such as CD40, immunoglobulin M, immunoglobulin D, cytoplasmic Cμ, and light chains κ, and λ. Conclusions These results indicate that human B cells develop from CD34+ cells in NOD/SCID mice to produce antigen-specific antibody with in vivo primary stimulation. This system provides a powerful and versatile tool for studying the entire process of human B-lymphocyte development and producing specific human monoclonal antibodies.