Serum antibodies to peripheral nerve tissue in acute Guillain-Barré syndrome in relation to outcome of plasma exchange

Pathogenesis of Guillain-Barré syndrome

Recent neurophysiological and pathological studies have led to a reclassification of the diseases that underlie Guillain-Barré syndrome (GBS) into acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor and sensory axonal neuropathy (AMSAN) and acute motor axonal neuropathy (AMAN). The Fisher syndrome of ophthalmoplegia, ataxia and areflexia is the most striking of several related conditions. Significant antecedent events include Campylobacter jejuni (4-66%), cytomegalovirus (5-15%), Epstein-Barr virus (2-10%), and Mycoplasma pneumoniae (1-5%) infections. These infections are not uniquely associated with any clinical subtype but severe axonal degeneration is more common following C. jejuni and severe sensory impairment following cytomegalovirus. Strong evidence supports an important role for antibodies to gangliosides in pathogenesis. In particular antibodies to ganglioside GM1 are present in 14-50% of patients with GBS, and are more common in cases with severe axonal degeneration associated with any subtype. Antibodies to ganglioside GQ1b are very closely associated with Fisher syndrome, its formes frustes and related syndromes. Ganglioside-like epitopes exist in the bacterial wall of C. jejuni. Infection by this and other organisms triggers an antibody response in patients with GBS but not in those with uncomplicated enteritis. The development of GBS is likely to be a consequence of special properties of the infecting organism, since some strains such as Penner 0:19 and 0:41 are particularly associated with GBS but not with enteritis. It is also likely to be a consequence of the immunogenetic background of the patient since few patients develop GBS after infection even with one of these strains. Attempts to match the subtypes of GBS to the fine specificity of anti-ganglioside antibodies and to functional effects in experimental models continue but have not yet fully explained the pathogenesis. T cells are also involved in the pathogenesis of most or perhaps all forms of GBS. T cell responses to any of three myelin proteins, P2, PO and PMP22, are sufficient to induce experimental autoimmune neuritis. Activated T cells are present in the circulation in the acute stage, up-regulate matrix metalloproteinases, cross the blood-nerve barrier and encounter their cognate antigens. Identification of the specificity of these T cell responses is still at a preliminary stage. The invasion of intact myelin sheaths by activated macrophages is difficult to explain according to a purely T cell mediated mechanism. The different patterns of GBS are probably due to the diverse interplay between antibodies and T cells of differing specificities.

Immune attack on the Schwann cell surface in acute inflammatory demyelinating polyneuropathy

The localization, mode of action, and roles of complement in the Guillain-Barre syndrome have been controversial. We used high-resolution immunocytochemistry to localize complement activation products in early stages of the acute inflammatory demyelinating polyneuropathy (AIDP) pattern of Guillain-Barre syndrome. Three AIDP subjects who were autopsied had had symptoms for 3 to 9 days at the time of death. Immunocytochemistry was performed on etched, epoxy resin-embedded sections, and the next thin section was compared by electron microscopy (thick/thin sections). Many fibers had a rim of the complement activation marker C3d and the terminal complement complex neoantigen C5b-9 along the outer surface of the Schwann cells. Ultrastructural analysis of these C3d-positive fibers showed mild vesicular changes of the outermost myelin lamellae. Vesicular degeneration was seen before the invasion of macrophages into the myelin, and was the predominant change in the subject with symptoms for 3 days. C3d staining was not found on myelin membranes. The results suggest that at least some forms of AIDP are complement mediated. We speculate that complement is activated by antibody bound to epitopes on the outer surface of the Schwann cell and that the resulting complement activation initiates the vesiculation of myelin.

Cerebrospinal fluid pheresis in Guillain Barré syndrome

While plasmapheresis is established in the treatment of acute polyneuroradiculitis, disabling pareses may last long, persisting neurological deficits remain frequent, and costs and side-effects are considerable. Repeated filtration of cerebrospinal fluid may remove pathogenetically relevant cells and polypeptides. Observations in 12 severe Guillain-Barré patients treated with CSF pheresis indicate that it is a safe and effective procedure. We hypothesize mechanisms of action of and potential indications for CSF pheresis as a more general concept. In inflammatory demyelinating polyneuropathy, CSF filtration could be combined with 'dynamic' cerebrospinal fluid pheresis, intravenous immunoglobulin therapy, cryoprecipitation, and/or immuno-adsorption to increase its effectiveness.

HLA antigens in patients with chronic inflammatory demyelinating polyneuropathy

In a group of 52 patients with a chronic inflammatory demyelinating polyneuropathy (CIDP), no significant associations were found with any of the HLA-A, B, C, DR or DQ antigens. No HLA association was found between the presence or absence of anti-neural antibodies or between the group of patients improving or not improving after intravenous immunoglobulin. These findings mean that we could not confirm results from the literature that suggest that CIDP is associated with the HLA-A1,B8,DR3 haplotype or--as recently was suggested--with the HLA-Cw7 or DR2 antigen.

No association with HLA-DR, -DQ or -DP alleles in Guillain-Barré syndrome

The distribution of HLA class II alleles in Guillain-Barré syndrome (GBS) has previously been reported only for HLA-DR. We report here the results of genomic typing for HLA-DR, -DQ and -DP allelic variability by restriction fragment length polymorphism analysis in 49 patients with a history of GBS. No association was found to HLA-DR, -DQ or -DP alleles or HLA-DR-DQ haplotypes. Subgrouping of patients according to severity of disease, as measured by disability or muscular weakness, or response to plasmapheresis treatment, also failed to reveal significant associations. These data suggest that HLA class II genes do not confer susceptibility to GBS.

Plasma exchange in Guillain-Barré syndrome: effect on anti-peripheral nerve myelin antibodies

Increased levels of anti-peripheral nerve myelin (anti-PNM) antibodies were demonstrated by ELISA in serum from 4 of 7 patients with Guillain-Barré syndrome (GBS). Treatment with plasma exchange (PE) was performed and 6 of the 7 patients showed clinical improvement with marked increase in muscular strength. One patient, however, continued to deteriorate during the treatment. No correlation between clinical improvement and levels of anti-PNM antibodies was observed. Whether the antibodies are of pathogenetic importance in GBS is therefore still unknown.