BackgroundRecently, the morbidity of orbital lymphoma increased gradually, and we have made deeper research in pathology, therapy and pathogenesis of the disease.There were few reports of mice model of orbital lymphoma up to now for its lower morbidity and culture difficulty.

ObjectiveThis study was to establish a mouse model of orbital diffuse large B cell lymphoma (DLBCL) by injection of systemic DLBCL cell line pfeiffer.

MethodsTen SPF BALB/c mice and 5 nod-SCID mice were radiated firstly using ¹³⁷Cs, with the absorption dose 3.5 Gy in the BALB/c mice and 2.6 Gy in the nod-SCID mice, and then pfeiffer cells were intraobitally injected in 4 eyes of BALB/c mice (orbital injection group) and suncutaneously injectied in 4 eyes of BALB/c mice and 4 eyes of nod-SCID mice (subcutaneous injection group) at the concentration of 1.5×10 ⁸/ml.The developing status of tumors were examined once per day and the growth curve was drawn.The tumors and nearby lymph nodes were obtained 54 days after injection for the preparation of 4 μm thickness of serial sections.Hemotoxylin-eosin staining was used to examine the histopathology of the tumors, and immunochemistry was employed to detect the expressions of CD20, CD79α and CD45RO proteins.The tumors were typed based on the expressions of CD10, BCL-6 and mum-1 in the specimens, and the expressions of Ki-67 and survivin were assyed to assess the prognosis of the tumor.All the results were compared with 3 diagnosed human orbital DLBCL sections.The use and care of the mice complied with Chinese Administration Rule of Laboratory Animal.

ResultsThe tumor formation rates were 100% in both the orbital injection group and subcutaneous injection group, and the tumors grew much faster in nod-SCID mice than BALB/c mice.Infiltration of tumor cells in lymph nodes were found in the subcutaneous injection group rather than the orbital injection group.The pathological features were accordant among the orbital injection group, subcutaneous injection group and human orbital DLBCL sections.The number of <50% and ≥50% CD20 ⁺ specimens was 3 and 5, CD79α was 2 and 6, CD45RO was 8 and 0 in the BALB/c mice; while that in the nod-SCID mice was 1 and 3 in CD20, 0 and 4 in CD79α, 4 and 0 in CD45RO; the number of human orbital DLBCL specimens was 1 and 2 in CD20, 1 and 2 in CD79α, 2 and 1 in CD45RO, without significant differences among them (all at P=1.00). No significant differences were seen in Ki-67 ⁺ number and survivin ⁺ number among the BALB/c mice, nod-SCID mice and human orbital DLBCL specimens (all at P=1.00). The detection of CD10, BCL-6 and mum-1 expressions indicated that the tumors of BALB/c mice, nod-SCID mice and human orbital DLBCL specimens all were the non-germinal center B cell-like types.

ConclusionsThe orbital and subcutaneous DLBCL mouse models are successfully established by injection of pfeiffer cell line.There are the same findings and features in biological behavior, pathology and immunohistochemistry in orbital, subcutaneous models with human orbitl DLBCL.Nod-SCID mice appear to be more suitable for the growth of lymphoma cells.