The occurrence of the
tumor-associated carbohydrate antigens defined by the
monoclonal antibodies (moabs) C 50 and 19-9 has been studied by immunoperoxidase staining of
formalin-fixed and
paraffin-embedded tissue specimens from normal, hyperplastic, adenomatous, and carcinomatous thyroid tissues. Epithelial expression of these
antigens was observed neither in normal nor in hyperplastic thyroid tissue. The
antigens were expressed in only 1 of 26
follicular adenomas and the staining in this case was weak and restricted to a few cells. In contrast, the expression of this
antigens is marked and progressive in carcinomatous tissues. A high proportion, 48 of 52
papillary carcinomas demonstrated C 50 reactivity, whereas 25 of these
tumors expressed the
CA 19-9 antigen. Of 25 follicular
carcinomas, 15 gave a positive staining for the CA 50 and 6 for the
CA 19-9 antigen.
CA 50 antigen expression was still detected in
tumor cells lacking the
CA 19-9 antigen and C 50 reactive material was found in all tissue specimens from
medullary carcinomas tested, whereas
CA 19-9 antigen staining was consistently negative. This indicates that the moab C 50 which reacts, like the moab 19-9, with the sialylated Lewisa (Lea)
blood group determinant also binds to other
antigens apart from the sialylated Lea in
CA 19-9 antigen negative
tumor cells. Although, the functional significance of CA 50 and
CA 19-9 antigen expression remains to be investigated, these results suggest that the demonstration of these
antigens could provide additional differential diagnostic parameters for the characterization of hyperplastic and neoplastic lesions of the thyroid gland. Further clinical studies will show whether these
carbohydrate antigens are useful
serum markers for the monitoring of
thyroid carcinomas.