Human-derived IgG level as an indicator for EBV-associated lymphoma model in Hu-PBL/SCID chimeras

BACKGROUND: Epstein-Barr virus (EBV) has a close association with various types of human lymphomas. Animal models are essential to elucidate the pathogenesis of human EBV-associated lymphomas. The aim of the present study is to evaluate the association between human IgG concentration and EBV-associated lymphoma development in huPBL/SCID mice. METHODS: Human peripheral blood lymphocytes (hu-PBL) from EBV-seropositive donors were inoculated intraperitoneally into SCID mouse. Immunohistochemical staining was used to examine differentiated antigens of tumor cells. EBV infection of the induced tumors was detected by in situ hybridization. IgG concentrations in the serums of 12 SCID mice were measured by unidirectional immunodiffusion assay. RESULTS: 21 out of 29 mice developed tumors in their body. Immunohistochemical staining showed that all induced tumors were LCA (leukocyte common antigen) positive, B-cell markers (CD20, CD79a) positive, and T-cell markers (both CD3 and CD45RO) negative. The tumors can be diagnosed as human B-cell lymphomas by these morphological and immunohistochemical features. In situ hybridization exhibited resultant tumor cells had EBV encoded small RNA-1 (EBER-1). Human-derived IgG could be found in the serum from SCID mice on the 15(th )day following hu-PBL transplantation, and IgG levels increased with the tumor development in 6 hu-PBL/SCID chimeras. CONCLUSIONS: Intraperitoneal transfer of hu-PBLs from EBV+ donors to SCID mice leads to high human IgG levels in mouse serum and B cell lymphomas. Our findings suggest that increasing levels of human-derived IgG in peripheral blood from hu-PBL/SCID mice could be used to monitor EBV-related human B-cell lymphoma development in experimental animals.