Study design: Serum antibody titers against 10 different glycosphingolipids were investigated by enzyme-linked immunosorbent assay in three groups of patients: patients with acute sciatica (Group IA, radicular pain for 32 +/- 36 days, n = 68), a subgroup of these patients 4 years later (Group IB, n = 23), and patients undergoing lumbar discectomy because of disc herniation (Group II, n = 37).
Objectives: To investigate the immunologic response in sciatica patients by analyzing circulating autoantibodies against glycosphingolipids, molecules highly expressed in cells from the nervous system, and the possible correlation of such antibodies to clinical and imaging findings as well as to subjective symptoms.
Summary of background data: The titers of glycosphingolipid antibodies are elevated in neurologic diseases with autoimmune stimulation such as Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy.
Methods: Antiglycosphingolipid antibodies were assayed by a microtiter enzyme-linked immunosorbent assay method. Antibody titers were related to a healthy population by a method that judges all positive results (positive result = patient sera/pooled blood donor serum >2, at titer 1/400) as indicating a pathologic condition.
Results: Increased levels of circulating antibodies against one or more glycosphingolipids were detected in 71% of patients with acute sciatica, in 61% of sciatica patients at a 4-year follow-up visit (eight antigens analyzed) and in 54% in patients undergoing discectomy. These frequencies were somewhat higher than, and in the last group similar to, those reported for generalized nervous system disorders with autoimmune involvement. In the acute sciatica patients, positive neurologic findings were associated with increased levels of two of the examined antibodies: 3'LM1 (immunoglobulin M and/or immunoglobulin G), P = 0.023, and GD1a (immunoglobulin M), P = 0.017.
Conclusion: The presence of glycosphingolipid antibodies in patients with sciatica and disc herniation suggests an activation of the immune system and thus a process possibly involved in the pathophysiology of sciatica. The autoimmune response was not limited to antibodies against one specific glycosphingolipid target; rather, an overall increase in autoantibodies against nervous system-associated glycosphingolipids was observed. These results encourage further studies of the pathophysiologic and clinical relevance of autoimmune responses in patients with sciatica and disc herniation.