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Thyroid growth stimulating activity in highly purified IgG-fractions of patients with nonimmune thyroid diseases
M D Oethinger1, B E Wenzel, P C Scriba
1Department of Medicine, Medical University of Lübeck, FRG.
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. IgG-fractions from patients with nontoxic goiter (n = 30), nontoxic recurrent goiter (n = 8), toxic-nodular goiter (n = 15) and carcinoma of the thyroid (n = 4) were highly purified on DEAE-Sepharose and additionally 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 microU/ml bTSH by 326% +/- 96% (range: 222% - 497%, p less than 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%, Rec. 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% (NTG: 33%, Rec. 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.
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. IgG-fractions from patients with nontoxic goiter (n = 30), nontoxic recurrent goiter (n = 8), toxic-nodular goiter (n = 15) and carcinoma of the thyroid (n = 4) were highly purified on DEAE-Sepharose and additionally 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 microU/ml bTSH by 326% +/- 96% (range: 222% - 497%, p less than 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%, Rec. 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% (NTG: 33%, Rec. 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.