Eosinophil depletion protects mice from tongue squamous cell carcinoma induced by 4-nitroquinoline-1-oxide.

Aims: Tumor-associated tissue eosinophilia (TATE) has been correlated with prognosis in oral squamous cell carcinoma (OSCC). This study aimed to investigate whether eosinophils depletion affects experimental oral carcinogenesis.
Methods and Results: BALB/c (wild type - WT) and eosinophil-deficient (Δdb/GATA-1) mice were treated with the carcinogen 4-nitroquinoline-1-oxide (4NQO) in drinking water for 28 weeks. Tongues were collected for histopathological and immunohistochemical analysis, as well as for the evaluation of cytokines/chemokines by ELISA. The tongue SCC induced by 4NQO was associated with a rise in eosinophil numbers. WT-treated group showed a significantly increased incidence of SCC, with higher cytological atypia, in comparison with Δdb/GATA-1 mice. Consistently, the proliferative index was higher in WT compared to the Δdb/GATA-1-treated group. No significant changes in the concentration of CCL3, CCL11 and TNF-α were detected for both groups after 4NQO treatment.
Conclusions: These results suggest that eosinophils might be responsible for the deleterious outcome of experimental tongue carcinogenesis, given that their ablation protects mice from OSCC.