Immunohistological study of intervertebral disc herniation of lumbar spine.

In order to observe histological changes in the extruded and sequestrated intervertebral disc, we conducted pathological and immunological examinations of herniated disc materials taken at the time of discectomy. There were 49 disc materials (from 38 men and 10 women [aged 19 to 78 years; average, 36.6 years]). The herniation was classified into four types, based on the intraoperative observations: protrusion (P), subligamentous extrusion (SE), transligamentous extrusion (TE), and sequestration (S). There were 19 P type discs, 3 SE type, 10 TE type, and 17 S type. The surgical specimens were stained with hematoxylin-eosin, as well as immunohistological staining with the labelled streptavidin biotin method, using human T-cell, human B-cell, and human macrophage antibodies. Inflammatory-cell infiltration was observed at the border of the disc. These findings were present in 19 discs (70%) of the 27 discs of TE and S types (10 TE and 17 S types), but were not seen in the 22 discs of P and SE types (19 P and 3 SE types). Immunohistological staining of the area with inflammatory-cell infiltration revealed the presence of T cells and macrophages, which suggested that this cell infiltration originated from T cells and macrophages, and that the spontaneous resorption of the disc may have resulted from the phagocytic activities of these cells.