Expression of chemokine receptor CXCR3 and its ligand, mig, in gastric and thyroid marginal zone lymphomas. Possible migration and autocrine mechanism.

Chemokine receptors mediate the migration of lymphocytes through the binding of ligands, and the expression is differentially regulated in lymphocyte subsets. CXCR3 is usually expressed in Th1 T cells, however, recently is reported to be expressed in B cell chronic lymphocytic leukemia, mucosa-associated lymphoid tissue type lymphoma (MALT) (extranodal marginal zone lymphoma), and other B cell non-Hodgkin lymphomas. Our study was designed to investigate the expression of CXCR3 and its ligand Mig, and their relationships in MALT using immunohistochemistry. In addition, CCR4, which is characteristic Th2 helper phenotype, and its ligand thymus and activation-regulated chemokine (TARC), were compared with CXCR3, as Th1 phenotype. We studied 14 cases of gastric B cell lymphoma [low-grade MALT, 5 cases; high-grade MALT, 5 cases; and diffuse large (DL), 4 cases] and 16 cases of thyroid B cell lymphoma [low-grade MALT, 4 cases; high-grade MALT, 5 cases; and DL, 7 cases]. CXCR3-expressing lymphoid cells were detected in all cases. In double immunostaining (CXCR3-CD20), gastric and thyroid low/high MALT showed CXCR3-positive neoplastic B cells, but DL, except two cases, did not. In DL, CXCR3-positive lymphoid cells were mainly reactive T-cells (CD3-positive cells). Mig was expressed mainly in stromal cells (histiocytes, macrophages, fibroblasts, and endothelial cells). In gastric lymphoma, low-grade MALT contained abundant Mig-strongly expressing cells, while staining in high-grade MALT and DL was mild. In thyroid lymphoma, staining was strong in low- and high-grade MALT, but moderate in DL. In double-staining, CXCR3-Mig-coexpressing lymphoma cells were abundant in high MALT of the stomach and thyroid, but rare in other subtypes. TARC-positive cells and CCR4-positive cells were rarely encountered in all cases. Our results indicate a tendency for low-grade MALT to contain CXCR3(+)Mig- lymphoma cells, high-grade to contain CXCR3(+)Mig+ and DL to contain CRCR3(-)Mig- lymphoma cells. We speculate that CXCR3 is associated with migration of lymphoma cells in low-grade MALT, and autocrine function in high-grade MALT, and not associated with any function in DL.