Phenotypic and functional analysis at the clonal level of infiltrating T lymphocytes in papillary carcinoma of the thyroid: prevalence of cytolytic T cells with natural killer-like or lymphokine-activated killer activity.

We investigated the phenotype and function of thyroid tumor-, metastatic lymph node-, and peripheral blood-derived T lymphocytes of four patients with papillary thyroid cancer. Both phenotypic analysis of freshly isolated cells and clonal analysis, using a high efficiency cloning technique, were performed. For comparison, intrathyroid and peripheral blood T lymphocytes derived from patients with autoimmune thyroid diseases (Graves' disease and Hashimoto's thyroiditis) have been studied. In papillary cancer, the phenotype of thyroid and lymph node-derived T lymphocytes did not differ from that of peripheral blood lymphocytes of the same patients or lymphocytes from normal peripheral blood. At variance with respect to autoimmune thyroid disease, activation markers were poorly represented. The functional analysis of T cell clones showed similar proportions of interleukin-2-producing (helper-inducer) clones in thyroid, lymph node, and peripheral blood, slightly lower than in Hashimoto's thyroiditis and slightly higher than in Graves' disease. With regard to effector function, we found lower proportion of clones with cytolytic activity in a lectin-dependent assay compared to that in Hashimoto's thyroiditis. Interestingly, however, the proportions of cytolytic clones displaying cytolytic activity against the neoplastic cell line K562 (natural killer-like activity) or fresh unrelated tumor cells (lymphokine-activated killer activity) were relatively high in thyroid cancer infiltrates.