[Affinity of estrogen binding in the cultured spinal ligament cells: an in vitro study using cells from spinal ligament ossification patients].

This immunological study investigated the effects of estrogen as a potential causative factor for spinal ligament ossification (such as ossification of the posterior longitudinal ligament, OPLL; ossification of the yellow ligament, OYL; and ossification of the anterior longitudinal ligament, OALL). The serum total estrogen (estron + estradiol + estriol) level in the OPLL patients and controls was measured by radioimmunoassay. To determine any difference in the affinity of the estrogen, 3,17 beta-estradiol receptors of cultured spinal ligament cells obtained from OPLL patient were detected by receptor binding assay, and compared with cells from controls. Additionally, to evaluate the responses of cultured spinal ligament cells to stimulation by 3,17 beta-estradiol, examined the production of bone Gla protein (BGP) in medium, the rate of tritiated thymidine (3H-TdR) uptake, and change in affinity of transforming growth factor-beta 1 (TGF-beta 1) receptor on those cells with 3,17 beta-estradiol added (E2+ group), and compared the results with those when 3,17 beta-estradiol was not added (E2- group). The serum total estrogen level was significantly higher in OPLL patients than in controls, and the level increased with increasing extent of ligament ossification. Cultured cells obtained from OPLL patients had receptors with a higher affinity for 3,17 beta-estradiol than did cells from controls. Cells obtained from OPLL patients responded to the stimulation by 3,17 beta-estradiol, accelerated BGP production, and elevated the 3H-TdR uptake. However, cells from controls showed no change in the stimulation by 3,17 beta-estradiol.(ABSTRACT TRUNCATED AT 250 WORDS)