title: Conversion of TBAb response to TSAb response by anti-human IgG antibody.
abstract: Previously, we reported the conversion phenomenon (CP) of thyroid blocking antibody (TBAb) to thyroid stimulating antibody (TSAb) by induced cAMP production during incubation of TBAb-bound porcine thyroid cells (PTC) with rabbit anti-IgG Ab. In the present experiment we examined the CP by TBAb-positive sera with high TSH binding inhibitor immunoglobulin (TBII) activity in primary hypothyroidism. Two patients with extremely high TBII patients; patient No.1 (35 yo male) with TSH 26.5μU/ml, TSAb negative, TBII 4,600 U/L, TBAb100% and patient No.2 (40 yo female) with TSH 4.5μU/ml, TSAb negative, TBII 1,620 U/L, TBAb 99.8% were examined. Cyclic AMP production was examined by 2nd incubation (3h) of anti-IgG Ab with TBAb-bound PTC that was made by 1st incubation (0.5h) of TBAbpositive serum and PTC. When sera (0.001-0.05 ml) of patient No.1 and No.2 were tested, cAMP production showed 980- 3,700% and 570-3,000% in a dose-dependent manner, respectively. Cyclic AMP production was also observed by anti- IgG fragments Ab [(Fab')2, Fab and light chain]. Cyclic AMP production by anti-F(ab')2 was higher than anti-Fab Ab, and cAMP by anti-κ Ab was significantly higher (>3 fold) than anti-λ Ab. Cyclic AMP production by TBAb-positive sera with high TBII activity (35-270 U/L) showed a correlation with serum TBII activity (R=0.76). The fact that all high TBAb-positive sera show the CP of TBAb to TSAb suggests that TSAb activity may be present in TBAb molecule and TBAb may be the precursor of TSAb.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ochi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kajita
authors.forename: Takashi
authors.initials: T
authors.lastname: Hachiya
authors.forename: Naoko
authors.initials: N
authors.lastname: Arata
authors.affiliation: Research Institute for Production Development, 15 Morimoto-cho, Simogamo, Sakyo-ku, Kyoto, 606-0805, Japan. k-y-ochi@blue.plala.or.jp.
authors.forename: Masaru
authors.initials: M
authors.lastname: Hamaoki
mesh_terms: D000328:Adult; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000097:blood*; D019138:Antibodies, Blocking / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating / Q000097:blood*; D008297:Male; D011485:Protein Binding / Q000502:physiology; D011817:Rabbits
chemical_list: D000888:Antibodies, Anti-Idiotypic; D019138:Antibodies, Blocking; D015415:Biomarkers; D018828:Immunoglobulins, Thyroid-Stimulating; C048844:anti-IgG