HLA class II expression in well differentiated thyroid carcinoma: correlation with clinicopathological features

Area of Science:

• Immunology
• Oncology
• Pathology

Background:

• Lymphocytic infiltration and aberrant Human Leukocyte Antigen (HLA) class II antigen expression on malignant thyroid epithelial cells are implicated in anti-thyroid cancer immune responses.
• Understanding these immune markers is crucial for thyroid cancer prognosis and treatment.

Purpose of the Study:

• To investigate the aberrant expression of HLA class II alpha and beta chains in well-differentiated thyroid carcinomas.
• To correlate these findings with tumor-infiltrating lymphocytes and clinicopathological features.
• To explore potential differences in HLA class II expression between papillary and follicular thyroid carcinomas.

Main Methods:

• Immunohistochemical analysis of HLA class II alpha and beta chains in primary thyroid tumors and metastases.
• Quantification and distribution assessment of tumor-infiltrating lymphocytes (CD45R0+).
• Correlation of immunohistochemical findings with clinicopathological data using Fisher's exact test.

Main Results:

• Aberrant HLA class II beta chain expression was observed in 28% of papillary and 15% of follicular carcinomas.
• All metastases were negative for both HLA class II alpha and beta chains.
• Significant correlations were found between aberrant HLA class II expression, tumor-infiltrating lymphocytes, and vessel invasion (p < 0.05).
• No correlation was observed between aberrant HLA class II expression and lymph node or distant metastasis occurrence.

Conclusions:

• HLA class II antigen expression on thyroid carcinoma cells is elevated during invasive growth.
• The local immune response to HLA class II antigens may inhibit the metastatic spread of positive tumor cells.
• Distinct HLA class II chain expression patterns in follicular and papillary thyroid carcinomas suggest differing regulatory mechanisms.