Growth factors and the skeletal system.

Two different proliferation assays have been used to measure the proliferative Potential of IgG-fractions from 57 patients with nontoxic goiter of an iodine-deficient area: primary human thyroid epithelial cells (TEC) and the thouroughly investigated FRTL-5 cell line. IgGfractions from patients with nontoxic goiter (n = 30), nontoxic recurrent goiter (n = 8), toxicnodular goiter (n = 15) and Carcinoma of the thyroid (n = 4) were highly purified on DEAE-Sepharose and additionaly Protein A-Sepharose in some cases. The two proliferation assays gave contradictory results: primary cultures of human thyroid epithelial cells (TEC) could not be stimulated by any of the patient's IgG-fractions nor by bTSH. The FRTL-5 cells, however, were stimulated with 10 / /U/ml bTSH by 326% ± 96% (ränge: 222% 497%, p < 0.001). In one experimental series, 72% of all patients exceeded mean + 2 SD of normal controls, when the Stimulation index was referred to the effect of bTSH (NTG: 77%, Ree. G.: 88%, Tox. G.: 53%, Ca. thyroid: 75%). With a different method of calculation Stimulation index referred to the basal value the number of patients above mean + 2 SD of normal controls decreased to 30% 1 Abbreviations used: AC-activity, activity of the adenylate-cyclase; bTSH, bovine thyroidea stimulating hormone; Ca. thyroid, Carcinoma of thyroid; FRTL-5 cells, Fischer's rat thyroid cell line 5; GD, Graves' disease; 3 H-TdR, 3 H-Thymidine; IBMX. 3-isobutyl-1-methyl-xanthine; MAB, microsomal antibody; NTG, non-toxic goitre; PBS, phosphate buffered saline; Ree. goiter, recurrent goiter; SD, Standard deviation; Sl, Stimulation index; TAB, thyroglobulin antibody; TBII, TSH-binding inhibiting immunoglobulin; TGI, thyroid growth stimulating immunoglobulin; Tox. goiter. toxic goiter, TSI. thyroid stimulating immunoglobulin. Key-words: Non-immune thyroid disease, thyroid growth stimulating antibody (TGI), FRTL-5 cells, human thyroid epithelial cells (TEC). Correspondence to. Dr. B.E. Wenzel, Department of Medicine, Cell and Immunobiological Laboratory, Medical University of Lübeck, Ratzeburger Allee 160, D 2400 Lübeck, FRG. Received January 24, 1989; aeeepted June 20,1989. (NTG: 33%, Ree. G.: 12,5%, Tox. G.: 33%, Ca. thyroid: 25%). Statistical analysis, however, of results of different patient groups compared to the normal control group failed to show any significance.