Epstein-Barr virus (EBV)-associated lymphoproliferations in severe combined immunodeficient mice transplanted with Hodgkin's disease lymph nodes: implications of EBV-positive bystander B lymphocytes rather than EBV-infected Reed-Sternberg cells

Abstract

To establish an in vivo model for the study of Hodgkin's disease and Reed-Sternberg (RS) cells, 25 lymph node tissue samples involved by Hodgkin's disease were grafted into severe combined immunodeficiency (SCID) mice. Ten Epstein-Barr virus (EBV)-associated tumors were obtained in SCID mice. EBV-positive tumors growing in SCID mice were correlated with the presence of EBV-positive nonneoplastic B cells in patient tumors (90% v 26.6%; P>.01) and was independent of the EBV status of RS cells. Our results suggested that EBV-positive tumors growing in SCID mice originated from normal EBV-positive small lymphocytes (bystander B lymphocytes). We also compared the characteristics of these tumors with those obtained after transplantation of 15 non-Hodgkin's lymphoma and four reactive lymph nodes. The latent period to observe a growing tumor in SCID mice was similar between the two groups (12.86 +/- 5.59 weeks for Hodgkin's disease v 13.6 +/- 5.36 weeks for non-Hodgkin's lymphoma and reactive lymph nodes). The relatively high number of EBV-positive small lymphocytes detected in Hodgkin's disease and T-cell lymphoma compared with B-cell lymphoma may account for the greater percentage of EBV- positive tumors obtained in SCID mice. Our results show that SCID mice do not provide the growth conditions that are required for in vivo growth of RS cells. We noted in some SCID tumors, the presence of binucleated and/or multinucleated giant cells resembling RS cells. However, the presence of such cells was not restricted to mice grafted with lymph nodes involved by Hodgkin's disease. We postulate that in previous reports, cells resembling RS cells were just binucleated EBV- positive lymphoma blastoid cells rather than actual RS cells.

Reed-Sternberg cells and "bystander" lymphocytes in lymph nodes affected by Hodgkin's disease are infected with different strains of Epstein-Barr virus

“…Tumors were obtained from each biopsy and then established in vitro, providing cell lines L1, L2, L3, and L4, corresponding to patients P1, P2, P3, and P4, respectively. As previously reported (13), the L1, L2, L3, and L4 cell lines exhibited a phenotype of activated B lymphocytes with expression of CD19, CD20, CD21, CD22, CD23, and CD30 antigens, while T-cell antigens (CD3, CD4, and CD8) were not detected (data not shown). In addition, LMP-1 and EBV nuclear antigen 2 were also expressed in these lymphoblastoid cell lines known to originate from EBV-positive reservoir lymphocytes present in the original lymph nodes (13,15).…”

“…As previously reported (13), the L1, L2, L3, and L4 cell lines exhibited a phenotype of activated B lymphocytes with expression of CD19, CD20, CD21, CD22, CD23, and CD30 antigens, while T-cell antigens (CD3, CD4, and CD8) were not detected (data not shown). In addition, LMP-1 and EBV nuclear antigen 2 were also expressed in these lymphoblastoid cell lines known to originate from EBV-positive reservoir lymphocytes present in the original lymph nodes (13,15). The clonality of these cell lines was analyzed by PCR for immunoglobulin and T-cell-receptor ␥ chain gene rearrangements (17,19) and by Southern blot analysis of the fused terminal fragments of episomal EBV (1,9).…”

“…However, in most EBV-positive cases of HD, involved lymph nodes also contain rare EBV-positive bystander B lymphocytes, also called reservoir lymphocytes, but it is not known whether these two cell types (i.e., RS cells and reservoir lymphocytes) are infected by the same or different viral strains. To answer this question, we took advantage of our previous findings that inoculation of cells isolated from lymph nodes involved in HD into SCID mice induced lymphoblastoid-EBV-positive tumors originating from the reservoir lymphocytes and not from RS cells (13). These EBV-positive tumors could thus be used to isolate EBV strains present in reservoir lymphocytes, allowing comparison with the strains present in the whole lymph nodes.…”

“…Tumors growing in SCID mice are derived from EBV-positive reservoir lymphocytes and not from RS cells. Cell suspensions were prepared from lymph nodes involved in HD and inoculated subcutaneously into SCID mice as previously described (13). Tumors were obtained from each biopsy and then established in vitro, providing cell lines L1, L2, L3, and L4, corresponding to patients P1, P2, P3, and P4, respectively.…”

Alterations in the Rho pathway contribute to Epstein-Barr virus–induced lymphomagenesis in immunosuppressed environments

“…10 It was also reported that EBVpositive tumors arising after the engraftment of lymph nodes from patients with Hodgkin lymphoma were derived from bystanderquiescent EBV-positive B lymphocytes and not from the EBVpositive Reed-Sternberg cells. 34 In immunocompromised patients, such as those with HIV infections and organ transplantations, EBV plays a carcinogenic role in the development of NHL, including DLBL, Burkitt lymphoma, extranodal NK/T-cell lymphoma of the nasal type, and nasopharyngeal cancer. 5 Indeed, the most frequent histological type of posttransplant lymphoproliferative disease is EBV 1 -DLBL.…”