Study Design. An examination of surgically obtained herniated lumbar disc t
issues performed by using immunohistochemical staining and the DNA nick end
labeling method.
Objective. To investigate the cell type that expresses Fas ligand (FasL) an
d any evidence of apoptosis of the disc cells in herniated lumbar disc tiss
ues.
Summary of Background Data. The Fas/FasL system is involved in delivering a
death signal that rapidly commits the cells to apoptosis. In the authors'
previous study, the expression of Fas on disc cells was identified in herni
ated lumbar disc tissue.
Methods. Twenty-three herniated lumbar disc tissues (contained disc, n = 9;
noncontained disc, n = 14) were examined to investigate the cell type that
expresses FasL and any evidence of apoptosis of the disc cells by using im
munohistochemical staining and the DNA nick end labeling method, respective
ly. The percentage of Fast-positive disc cells was calculated and compared
with clinical and radiologic data.
Results. FasL was expressed in the cytoplasm of the disc cells, and nuclear
DNA fragmentation in a few disc cells was identified. A higher degree of F
asL expression in disc cells was found in noncontained discs than in contai
ned discs (P < 0.05). The percentage of Fast-positive disc cells significan
tly increased with the patient's age (P < 0.05), but not with the degree of
disc degeneration (P > 0.05).
Conclusion. The current results indicate that disc cells, after herniation,
undergo apoptotic cell death via autocrine or paracrine FasL mechanisms by
the disc cells themselves.