Expressions of CXCL12, CXCL10 and CCL18 in Warthin tumors characterized pathologically by having a lymphoid stroma with germinal centers

Abstract

The Warthin tumor is a benign neoplasm of the salivary glands, histologically, the tumor has an oncocytic epithelial component forming uniform rows of cells surrounded by cystic spaces associated with a lymphoid stroma often showing the presence of germinal centers. The lymphoid stroma is a representative microscopic finding. If this lymphocytic accumulation is active, some sort of transmitter should exist between the Warthin tumor cells and lymphocytes. C-X-C motif chemokine ligand (CXCL) 12, CXCL10 and C-C motif chemokine ligand 18 (CCL18) are a chemoattractant for lymphocytes in vivo. There is no report on the relationship between these chemokines and Warthin tumors. In this study, we investigated these chemokines expressions in 20 Warthin tumors using immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR). For comparison, we also enrolled samples of pleomorphic adenoma, which is another benign salivary gland tumor type without prominent lymphocytic infiltration. All Warthin tumors were immunopositive for CXCL12 and CXCL10, and these reactivities were diffuse. Meanwhile, the majority of pleomorphic adenomas were immunonegative for CXCL12 (95%), CXCL10 (80%) and CCL18 (85%). Warthin tumor and pleomorphic adenoma cases were significantly different in these immunostaining expressions (CXCL12, p<0.001; CXCL10, p<0.001; CCL18, p=0.024). We examined CXCL12, CXCL10 and CCL18 mRNA expressions of 3 representative Warthin tumor samples, each having these chemokines immunopositive areas detected by RT-PCR. Finding CXCL12 and CXCL10 expressions indicate that these chemokines may play a part in the formation of a lymphoid stroma within Warthin tumors. In regards to this phenomenon, the participation of CCL18 might be restrictive compared to CXCL12 and CXCL10.