TUMOR-SPECIFIC DEPOSITION OF IMMUNOGLOBULIN-G AND COMPLEMENT IN PAPILLARY THYROID-CARCINOMA

Despite its predilection for multifocal growth and regional metastasis , papillary thyroid carcinoma (PTC) is a clinically indolent malignanc y with an exceptionally favorable long-term prognosis. Together with t he often striking inflammatory reaction present in PTC, its quiescent behavior has been suggested to reflect the activation of a tumor-induc ed immune response. To examine this possibility, eve have studied the deposition of immunoglobulins and complement in PTC tissue. Samples fr om 70 cases of neoplastic and autoimmune thyroid diseases, including P TC (n = 41), follicular, anaplastic, and medullary carcinomas (n = 12) , follicular adenoma (n = 6), Graves' disease (n = 8), and Hashimoto's thyroiditis (n = 3) were analyzed immunohistochemically. Cellular dep osits of immunoglobulin G (IgG), particularly subclasses IgG(1) and Ig G(4), and complement factors C3d, C4d, and C5 were shown in up to 89% of the PTC cases, whereas the other thyroid diseases studied showed li ttle or no cellular deposition. Nonneoplastic tissue of PTC-containing thyroid glands (n = 22) lacked staining for IgG in 50% of the cases, and 82% were devoid of complement. The results suggest a tumor-specifi c immune response in PTC with activation of the classical complement c ascade. Copyright (C) 1996 by W.B. Saunders Company