Paraneoplastic cerebellar autoantibodies associated with gynecological cancer bind to myenteric plexus neurons

'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 3: Anti-Yo/CDR2, anti-Nb/AP3B2, PCA-2, anti-Tr/DNER, other antibodies, diagnostic pitfalls, summary and outlook

Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa head antibodies' due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook.

Neural autoantibody profile of primary achalasia

The etiology and pathogenesis of primary achalasia are both unknown. Postulated mechanisms include autoimmune, viral-immune, and central neurodegenerative. The aim of this study is to investigate the serum profile of neural autoantibodies in patients with primary achalasia. Coded sera from 70 patients with primary achalasia and 161 healthy control subjects, matched in sex, age, and smoking habits, were screened for antibodies targeting neuronal, glial, and muscle autoantigens. No specific myenteric neuronal antibody was identified. However, the overall prevalence of neural autoantibodies in patients with primary achalasia was significantly higher than in healthy control subjects (25.7 vs. 4.4%, P < 0.0001). Most noteworthy was the 21.4% frequency of glutamic acid decarboxylase-65 antibody in patients with achalasia (versus 2.5% in control subjects), in the absence of diabetes or companion antibodies predictive of type 1 diabetes. This profile of autoantibodies suggests an autoimmune basis for a subset of primary achalasia.

Spectrum of centrosome autoantibodies in childhood varicella and post-varicella acute cerebellar ataxia

BACKGROUND

Sera from children with post-varicella infections have autoantibodies that react with centrosomes in brain and tissue culture cells. We investigated the sera of children with infections and post-varicella ataxia and related conditions for reactivity to five recombinant centrosome proteins: gammagamma-enolase, pericentrin, ninein, PCM-1, and Mob1.

METHODS

Sera from 12 patients with acute post-varicella ataxia, 1 with post-Epstein Barr virus (EBV) ataxia, 5 with uncomplicated varicella infections, and other conditions were tested for reactivity to cryopreserved cerebellum tissue and recombinant centrosome proteins. The distribution of pericentrin in the cerebellum was studied by indirect immunofluorescence (IIF) using rabbit antibodies to the recombinant protein. Antibodies to phospholipids (APL) were detected by ELISA.

RESULTS

Eleven of 12 children with post-varicella ataxia, 4/5 children with uncomplicated varicella infections, 1/1 with post-EBV ataxia, 2/2 with ADEM, 1/2 with neuroblastoma and ataxia, and 2/2 with cerebellitis had antibodies directed against 1 or more recombinant centrosome antigens. Antibodies to pericentrin were seen in 5/12 children with post-varicella ataxia but not in any of the other sera tested. IIF demonstrated that pericentrin is located in axons and centrosomes of cerebellar cells. APL were detected in 75% of the sera from children with post-varicella ataxia and 50% of children with varicella without ataxia and in none of the controls.

CONCLUSION

This is the first study to show the antigen specificity of anti-centrosome antibodies in children with varicella. Our data suggest that children with post-varicella ataxia have unique autoantibody reactivity to pericentrin.

Paraneoplastic gastrointestinal motor dysfunction: clinical and laboratory characteristics

OBJECTIVES

The aim of this study was to describe the clinical, manometric, and serological characteristics of 12 patients with paraneoplastic GI motor dysfunction and to assess the contributory role of diagnostic tests.

METHODS

Twelve patients diagnosed with malignant tumors and GI motor dysfunction were identified at the Mayo Clinic from 1985 to 1996.

RESULTS

Cancers identified were: nine small cell lung carcinoma (SCLC), one anaplastic lung adenocarcinoma, one retroperitoneal lymphoma, and one ovarian papillary serous adenocarcinoma. GI symptoms preceded the tumor diagnosis in all cases of SCLC (mean, -8.7 months, range, -1 to -24 months, n = 9). The diagnosis of a malignant tumor preceded the onset of GI symptoms in the three patients with other neoplasms (6, 12, and 24 months). Five of the nine patients found to have SCLC had no evidence of tumor on initial chest x-ray. One or more paraneoplastic autoantibodies were found in 10 of the 11 patients tested by autoimmune serology. Type 1 antineuronal nuclear antibody (ANNA-1 or anti-Hu) was detected in eight of the nine patients with SCLC (one patient was not tested). The patient with ovarian carcinoma had type 1 Purkinje cell cytoplasmic antibody (PCA-1 or anti-Yo). N-type calcium channel antibodies were found in one patient with SCLC, one with a retroperitoneal B cell lymphoma, and one with ovarian carcinoma. Gastric emptying was delayed in 89% (eight of nine tested) and 80% (four of five tested) had esophageal dysmotility. Autonomic reflex tests were abnormal in the seven patients tested.

CONCLUSIONS

The diagnosis of paraneoplastic GI motor dysfunction requires a high index of clinical suspicion. A panel of serological tests for paraneoplastic autoantibodies, scintigraphic gastric emptying, and esophageal manometry are useful as first-line screening tests. Seropositivity for ANNA-1, PCA-1, or N-type calcium channel-binding antibodies should prompt further evaluation for an underlying malignancy even when routine imaging studies are negative.

Antimyenteric neuronal antibodies in scleroderma

The pathogenesis of gastrointestinal (GI) dysmotility in scleroderma is incompletely understood, although previous studies have proposed a neuropathic mechanism. We studied patients with scleroderma as compared with other connective tissue disease patients and normal controls for the presence of circulating antibodies to myenteric neurons. Serial dilutions of sera were overlaid on rat intestine, double-labeled with antineurofilament antibody as a myenteric plexus marker, and imaged using indirect immunofluorescence techniques. High titer sera (> or = 1:50) from 19 out of 41 scleroderma patients stained myenteric neurons, whereas none of 22 normals or 5 patients with idiopathic GI dysmotility were positive. Although 6 out of 20 SLE and 6 out of 10 mixed connective tissue disease patients' sera stained myenteric plexus neurons, when positive sera were absorbed with calf thymus extract to remove antinuclear antibody, 15 scleroderma sera, 0 SLE, and 2 mixed connective tissue disease patients retained positive staining of myenteric neurons. Western blotting using actin and neuronal intermediate filament preparations failed to show immunoreactivity with scleroderma sera containing antimyenteric neuronal antibodies. Paraneoplastic sera associated with GI dysmotility stained myenteric neurons in a different pattern than seen with scleroderma sera. A positive correlation between the presence of Raynaud's phenomenon and antimyenteric neuronal antibodies was observed in scleroderma patients. Our results indicate that IgG antibodies reacting with myenteric neurons are present in many patients with scleroderma. Although the neuronal antigen has not yet been identified, the presence of myenteric neuronal antibodies in patients with GI dysmotility and scleroderma suggests a neuropathic process.