Impact of immunodeficiency on lingual carcinogenesis and lymph node metastasis in mice

Purpose: Carcinogenesis is mostly accompanied by inflammation and is shaped by immune responses, where the host immune system does not always appear to be a powerful active tool. Some studies have identified that T lymphocytes in the tumor microenvironment are indispensable for the process of distant metastasis. This study aimed to investigate the contradictory role of the immune system and to examine the impact of immunodeficiency on carcinogenesis and lymph node metastasis in mouse models. Methods: BALB/c mice, BALB/c nude mice, and CB-17SCID mice were treated with 50 mg/L 4-nitroquinoline-1-oxide (4NQO) in drinking water for 16 weeks followed by distilled water until 38 weeks. Three mice per group were sacrificed biweekly or every four weeks from week 4, and tongue lesions and regional lymph node metastases were evaluated. Results: There were no significant differences in the histological examination of carcinogenesis in immunocompetent and immunodeficient mice exposed to 4NQO. However, development of cancer in immunodeficient mice (12 weeks) was earlier than that in immunocompetent mice (28 weeks). Local lymph metastases were observed after 36 weeks in immunocompetent BALB/c mice as opposed to after 18 weeks in immunodeficient mice. Conclusion: Immunodeficiency could remarkably advance carcinogenic progression and lymph node metastasis but might not accelerate lymph node metastasis progression.