GROWTH-STIMULATING ANTIBODIES IN ENDEMIC GOITER - A REAPPRAISAL

OBJECTIVE Previous studies, using a variety of methods, have reported growth-promoting immunoglobulins (IGs) in a large proportion of patien ts with endemic goitre. We sought to determine whether thyroid growth- promoting immunoglobulins (TGI) are present in the serum of Indian pat ients with endemic goitre. DESIGN IgG was prepared by protein G-Sephar ose affinity purification and added to FRTL-5 thyroid cells in the pre sence of suboptimal concentrations of TSH. PATIENTS We studied 30 sequ ential patients with endemic goitre and 16 euthyroid controls without a goitre from the same area. MEASUREMENTS Two assays for thyroid cell growth were used: H-3-thymidine incorporation, and flow cytometric mea surement of the proportion of cells in the S phase and G(2)/M phase of the cell cycle. RESULTS Both assays were shown to detect growth produ ced by TSH and by thyroid stimulating antibodies in IgG preparations f rom 3 patients with Graves' disease. There was no significant increase in either H-3-thymidine incorporation or the distribution of cells in S or G(2)/M phase with IgGs from endemic goitre patients, and no diff erence between the effects of these IgGs and those from the normal sub jects. CONCLUSIONS Thyroid growth-promoting immunoglobulins cannot be detected in Indian patients with endemic goitre.