Immunogenetic and immunologic studies of differentiated thyroid cancer.

The authors have studied in detail human leukocyte antigen (HLA) association in 87 Hungarian patients with thyroid epithelial carcinoma. The authors also examined in a small group of patients, five parameters of cell-mediated immunity and related them to HLA as well as to lymphocytic infiltration of the tumor/normal tissue interface. HLA-DR1 was significantly associated with thyroid carcinoma; the strongest association was in patients with follicular histologic features and DR1 homozygotes were not at greater risk for thyroid cancer. The HLA-DR3 was nonsignificantly increased in patients with papillary or mixed histologic features. The HLA-DR1, 3 heterozygotes were highly associated with follicular carcinoma, carried no risk for papillary carcinoma, and an intermediate risk for tumors with mixed histologic features. Because of the small proportion of DR1, 3 heterozygotes in the follicular and mixed histologic group, its predictive value at the population level was low. Better predictive potential was shown for the phenotype DR1 and/or DR3. Neither metastatic disease nor age at diagnosis (less than 45 years) could be related to HLA phenotypes. Patients in all histologic variants showed some measure of cell-mediated immunity compared to controls. Patients with papillary carcinoma showed an overall better response than those with tumors with follicular or mixed histology. The HLA-DR could not be related to cell-mediated immune response. Patients with papillary carcinoma with a good cell-mediated immune response occurred with much lower infiltration of the tumor boundary with lymphocyte whereas the follicular carcinoma less cell-mediated immunity was associated with dense lymphocytic infiltration, suggesting the biological relevance of lymphocytic infiltration may be different for the two histologic variants.