Local production of the chemokines CCL5 and CXCL10 attracts CD8⁺⁺ T lymphocytes into esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a very common malignant tumor with poor prognosis in China. Chemokines secreted by tumors are pivotal for the accumulation of CD8⁺+ T lymphocytes within malignant lesions in several types of cancers, but the exact mechanism underlying CD8⁺+ T lymphocyte homing is still unknown in ESCC. In this study, we revealed that, compared with marginal tissues, the expression of both chemokine (C-C motif) ligand 5 (CCL5) and (C-X-C motif) ligand 10 (CXCL10) was upregulated in ESCC tissues. CCL5 expression was positively associated with the overall survival of patients. Meanwhile, RT-PCR data showed that the expression of CCL5 and CXCL10 was positively correlated with the local expressions of the CD8⁺+ T lymphocyte markers (CD8⁺ and Granzyme B) in tumor tissues. Correspondingly, CD8⁺+ T lymphocytes were more frequently CCR5- and CXCR3- positive in tumor than in peripheral blood. Transwell analysis showed both CCL5 and CXCL10 were important for the chemotactic movement of CD8⁺+ T lymphocytes. Our data indicate that CCL5 and CXCL10 serve as the key chemokines to recruit CD8⁺+ T lymphocytes into ESCC tissue and may play a role in patient survival.