Expression of Vascular Endothelial Growth Factor in Human Conjunctival Lymphoma

Abstract

Purpose: : Extranodal marginal zone B-cell lymphoma (EMZL) of the conjunctiva is a common tumor in ocular adnexal lymphomas in human; however, the mechanism underlying the tumor growth and angiogenesis has yet to be elucidated. In this study, we examined the expression of vascular endothelial growth factor (VEGF), known to be a tumor growth factor and an angiogenic factor, in human conjunctival EMZL.

Methods: : Seven conjunctival EMZLs and a reactive lymphoid hyperplasia (RLH), surgically removed, were examined in this study. Formalin-fixed, paraffin-embedded tissue sections were processed for hematoxylin & eosin staining, and immunohistochemistry with antibodies against VEGF and CD20, a B-cell marker. Colocalization of VEGF with CD20 was evaluated by double-staining immunohistochemistry. Monoclonal immunoglobulin heavy chain (IgH) gene rearrangement was determined by Southern blotting in DNA extracted from these tissues.

Results: : In conjunctival EMZLs, CD20-positive atypical lymphoid cells with monoclonal IgH gene rearrangement diffusely infiltrated the conjunctival stroma. In RLH, CD20-positive normal-appearing lymphocytes without monoclonality infiltrated the subepithelium. Immunoreactivity for VEGF was detected in the cytoplasm of CD20-positive cells, in which VEGF-immunopositive rate was 56 % and 13 % in conjunctival EMZL and RLH, respectively.

Conclusions: : These results suggest that VEGF is predominantly expressed in human conjunctival lymphoma cells, which may contribute to tumor growth and angiogenesis.

Keywords: conjunctiva • tumors • immunohistochemistry