Gangliosides GM1 and GM3 in the living cell membrane form clusters susceptible to cholesterol depletion and chilling.

Presence of microdomains has been postulated in the cell membrane, but two-dimensional distribution of lipid molecules has been difficult to determine in the submicrometer scale. In the present paper, we examined the distribution of gangliosides GM1 and GM3, putative raft molecules in the cell membrane, by immunoelectron microscopy using quick-frozen and freeze-fractured specimens. This method physically immobilized molecules in situ and thus minimized the possibility of artifactual perturbation. By point pattern analysis of immunogold labeling, GM1 was shown to make clusters of <100 nm in diameter in normal mouse fibroblasts. GM1-null fibroblasts were not labeled, but developed a similar clustered pattern when GM1 was administered. On cholesterol depletion or chilling, the clustering of both endogenous and exogenously-loaded GM1 decreased significantly, but the distribution showed marked regional heterogeneity in the cells. GM3 also showed cholesterol-dependent clustering, and although clusters of GM1 and GM3 were found to occasionally coincide, these aggregates were separated in most cases, suggesting the presence of heterogeneous microdomains. The present method enabled to capture the molecular distribution of lipids in the cell membrane, and demonstrated that GM1 and GM3 form clusters that are susceptible to cholesterol depletion and chilling.

[A case of neuralgic amyotrophy with antiganglioside antibody].

A 54-year-old-man experienced pain from his left shoulder to his left arm and had difficulty in lifting his arm after a febrile episode. Three weeks after the onset, he was admitted to our hospital. Neurological examination demonstrated weakness and atrophy of the left deltoid muscle. Deep tendon reflexes were normal and no pathological reflexes were elicited. CSF total protein was slightly increased. The occurrence rate of F-waves was decreased in the left upper limb. Magnetic resonance imaging (MRI) study of the cervical cord and brachial plexus with and without Gadolinium infusion showed no abnormalities. Serological study showed that IgM anticytomegalovirus antibody was positive, and that serum IgM anti-GalNAc-GD1a antibody and IgM anti-GM2 antibody were positive. Symptoms were improved after treatment with mecobalamin, 1.5mg/day. This case was considered neuralgic amyotrophy after cytomegalovirus infection. The antiganglioside antibodies may play some role in its pathogenesis.

Effects of phospholipids on antiganglioside antibody reactivity in GBS.

Serum antibody activities to mixtures of a ganglioside and various phospholipids were compared with those to a ganglioside alone in 30 anti-GM1 IgG-positive GBS patients and 30 anti-GQ1b IgG-positive Miller Fisher syndrome (MFS) patients. Anti-GM1-positive sera had higher antibody reactivities against a mixture of GM1 and several phospholipids including PA, PI and PS, than against GM1 alone. In contrast, in case of anti-GQ1b antibody, no phospholipid provided significant enhancement. Sphingomyelin provided decrease of the activity for both anti-GM1 and anti-GQ1b IgG. The effects of phospholipids must be considered to determine the pathogenetic role of antiganglioside antibodies in GBS and MFS.

[Internal ophthalmoplegia in acute oropharyngeal palsy with anti-GQ1b and anti-GT1a IgG antibodies].

A patient with acute oropharyngeal palsy associated with internal ophthalmoplegia was reported. A 13-year-old boy had fever and diarrhea for two days. Ten days after resolution of these symptoms, he noticed difficulty in speaking (day 1). Neurological findings on day 4 included bilateral mydriasis, right abducens nerve palsy, nasal voice with absent pharyngeal reflex. Although superficial sensation was preserved, vibratory sensation was reduced in distal limbs. Tendon reflexes were generally absent. Neither ataxia nor dysautonomia was seen. Serum anti-glycolipid antibody assay on day 4 disclosed elevated IgG antibodies to GQ1b and GT1a. His cerebrospinal fluid on day 21 contained 6 mononuclear cells/microl with 137 mg/dl of total protein. Nerve conduction study on day 5 showed minimal sensory nerve involvement. Quantitative sudomotor axon reflex test was normal in the lower extremities. Low dose pilocarpine eyedrops dilated his pupils. Although mild cerebellar-like ataxia appeared on day 5, intravenous immunoglobulin (0.4 g/kg/day for four days) rapidly improved his neurological abnormalities. IgG anti-GQ1b antibody might contribute not only oropharyngeal weakness but also internal ophthalmoplegia in this patient.

Asymmetrical weakness associated with central nervous system involvement in a patient with guillain-barrè syndrome.

Guillain-Barrè syndrome (GBS) is usually associated with symmetrical weakness, and therefore asymmetrical weakness may confuse diagnosis. We report on a patient with GBS subsequent to Campylobacter jejuni enteritis who had asymmetrical weakness with CNS involvement. The patient tested positive for anti-ganglioside antibodies, including anti-GM1 IgM, anti-GD1b IgG, and anti-GT1a IgG. Patients with GBS can manifest asymmetrical signs and symptoms attributable to CNS involvement. Prompt, accurate diagnosis and treatment of post-C. jejuni GBS is especially important because its prognosis is relatively poor.

Ganglioside complexes as new target antigens in Guillain-Barré syndrome.

Antibodies specific for a complex of gangliosides GD1a and GD1b (GD1a/GD1b) were found in sera from eight of 100 patients with Guillain-Barre syndrome (GBS) by the use of enzyme-linked immunosorbent assay and thin-layer chromatogram immunostaining. Those sera also had antibody activities to such ganglioside complexes as GD1a/GM1, GD1b/GT1b, and GM1/GT1b but had little or no reactivity to the each isolated antigen. Clustered epitopes of the ganglioside complex in the plasma membrane may be targeted by such an antibody, and interaction between the antibody and ganglioside complex may induce the neuropathy.