PROLIFERATING CELL NUCLEAR ANTIGEN IN HYPERTROPHIED SPINAL LIGAMENTS - IMMUNOHISTOCHEMICAL LOCALIZATION OF PROLIFERATING CELL NUCLEAR ANTIGEN IN HYPERTROPHIED POSTERIOR LONGITUDINAL LIGAMENT OF THE CERVICAL-SPINE

Study Design. An experimental immunohistochemical investigation using an antibody for proliferating cell nuclear antigen. Surgically-extirpa ted specimens of posterior longitudinal ligament tissues from patients with hypertrophy of the posterior longitudinal ligament and other dis orders of the cervical spine were analyzed. Objective. To analyze the developmental mechanism of hypertrophy of the posterior longitudinal l igament, the authors evaluated the growth activity of cells in the pos terior longitudinal ligament tissues by examining the immunolocalizati on of the proliferating cell nuclear antigen. Summary of Background Da ta. Although a number of cases of hypertrophy of the posterior longitu dinal ligament have been reported, the pathophysiology of ligament hyp ertrophy is still unclear. It is well established that the proliferati ng cell nuclear antigen is a cell proliferation marker, and immunohist ochemical analysis using an anti-proliferating cell nuclear antigen an tibody is of value in assessing the cell growth activity of several ti ssues. Methods. During anterior decompression surgery in the cervical spine, the authors extirpated posterior longitudinal ligament tissues in one piece from patients with hypertrophy of the posterior longitudi nal ligament, ossification of the posterior longitudinal ligament, cer vical disc herniation, and cervical spondylotic myelopathy. Midsagitta l sections of the specimens Were stained with an antibody against the proliferating cell nuclear antigen. Results. In cases of hypertrophy o f the posterior longitudinal ligament, immunostaining with the prolife rating cell nuclear antigen was detected in cells in the posterior lon gitudinal ligament, not only at the vertebral endplate level, but also at the midvertebral level. A similar distribution of proliferating ce ll nuclear antigen-positive cells was observed in cases of ossificatio n of the posterior longitudinal ligament. In cases of cervical disc he rniation, however, proliferating cell nuclear antigen! positive cells in posterior longitudinal ligament tissues were restricted to the vert ebral endplate level. No immunostaining with the proliferating cell nu clear antigen was seen in posterior longitudinal ligament tissues in c ases of cervical spondylotic myelopathy. Conclusions. Cell growth acti vity was accelerated in posterior longitudinal ligament tissues in cas es of hypertrophy of the posterior longitudinal ligament; such an unus ual phenotype of posterior longitudinal ligament cells was also expres sed in cases of ossification of the posterior longitudinal ligament, b ut not in cases of cervical disc herniation and cervical spondylotic m yelopathy, Therefore, up-regulation of the growth of posterior longitu dinal ligament cells may contribute to the development of hypertrophy of the posterior longitudinal ligament, and some common regulatory mec hanism(s) on the proliferation of posterior longitudinal ligament cell s seem to underlie the development of hypertrophy of the posterior lon gitudinal ligament and ossification of the posterior longitudinal liga ment.