Cyclosporine A effectively inhibits graft-versus-host disease during development of Epstein-Barr virus-infected human B cell lymphoma in SCID mouse.

We previously constructed human peripheral blood lymphocyte (hu-PBL)/severe combined immunodeficiency mouse (SCID) chimeras and induced human B-cell lymphomas associated with Epstein-Barr virus (EBV) in SCID mice. However, a number of SCID mice died of graft-versus-host disease (GVHD) during the early experimental course. The aim of this study was to test the efficacy of cyclosporine A (CSA) for prevention of GVHD and to define how CSA inhibits the occurrence of GVHD and the production of soluble interleukin (IL) 2 receptor (sIL-2R) in hu-PBL/SCID mice. No mouse died in the active EBV infection group with CSA administration, while 17 mice in three groups without CSA administration died of GVHD. Mortalities in these three groups were 55.56% (5/9), 30.43% (7/23), and 27.78% (5/18), and the medium life span was 17 days. Over the first 33 days after hu-PBL transplantation, serum level of human sIL-2R in hu-PBL/SCID chimeras was stable in the active EBV infection plus CSA group, while sIL-2R concentration gradually increased in the sera of mice with active EBV infection without CSA administration and peaked at 22 days. Thirty-two mice developed tumors among the 43 surviving SCID mice. There was no significant difference of tumor incidence between the active EBV infection groups with CSA and without CSA administration (P > 0.05). From their morphological and immunohistochemical features, as well as detection of human Alu-sequence and EBV in tumor cells, these EBV-induced tumors were identified as human B-cell lymphomas. Thus, CSA can strikingly inhibit GVHD in hu-PBL/SCID chimeras, and should therefore be effective to establish a stable SCID mouse model of human lymphoma associated with EBV. Treatment with CSA had no effect on the tumor incidence in hu-PBL/SCID chimeras after active EBV infection. Accordingly, serum level of sIL-2R is a valuable indicator of GVHD occurrence in hu-PBL/SCID chimeras.