Paraneoplastic neurological syndromes and onconeural antibodies: clinical and immunological aspects

Neuroendocrine carcinoma of the small intestine diagnosed as a result of paraneoplastic neurological syndrome

Paraneoplastic neurological syndromes, a diverse group of neurological syndromes, are associated with small cell lung, testicular, ovarian, and breast cancers; however, their association with neuroendocrine carcinoma of the small intestine remains unreported. In this report, we present the case of a 78-year-old man diagnosed with neuroendocrine carcinoma of the small intestine and experienced symptoms such as subacute progressive numbness of the extremities and impaired gait. These symptoms were diagnosed as tumor-associated neurological syndrome. The patient had also undergone pyloric gastrectomy for early-stage gastric cancer several years prior to the appearance of the neurological symptoms. Therefore, we could not determine whether the tumor-related neurologic syndrome was owing to gastric cancer or neuroendocrine carcinoma of the small intestine; however, one of these conditions was the cause of the neuropathy. The gait disturbance and numbness relatively improved after surgery for the neuroendocrine carcinoma of the small intestine, suggesting that the neuroendocrine carcinoma of the small intestine likely caused the paraneoplastic neurological syndrome. Collectively, we present a unique report highlighting the putative relationship between small bowel neuroendocrine carcinoma and tumor-associated neurologic syndromes.

Treatable Ataxias: How to Find the Needle in the Haystack?

Treatable ataxias are a group of ataxic disorders with specific treatments. These disorders include genetic and metabolic disorders, immune-mediated ataxic disorders, and ataxic disorders associated with infectious and parainfectious etiology, vascular causes, toxins and chemicals, and endocrinopathies. This review provides a comprehensive overview of different treatable ataxias. The major metabolic and genetic treatable ataxic disorders include ataxia with vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann-Pick disease type C, autosomal recessive cerebellar ataxia due to coenzyme Q10 deficiency, glucose transporter type 1 deficiency, and episodic ataxia type 2. The treatment of these disorders includes the replacement of deficient cofactors and vitamins, dietary modifications, and other specific treatments. Treatable ataxias with immune-mediated etiologies include gluten ataxia, anti-glutamic acid decarboxylase antibody-associated ataxia, steroid-responsive encephalopathy associated with autoimmune thyroiditis, Miller-Fisher syndrome, multiple sclerosis, and paraneoplastic cerebellar degeneration. Although dietary modification with a gluten-free diet is adequate in gluten ataxia, other autoimmune ataxias are managed by short-course steroids, plasma exchange, or immunomodulation. For autoimmune ataxias secondary to malignancy, treatment of tumor can reduce ataxic symptoms. Chronic alcohol consumption, antiepileptics, anticancer drugs, exposure to insecticides, heavy metals, and recreational drugs are potentially avoidable and treatable causes of ataxia. Infective and parainfectious causes of cerebellar ataxias include acute cerebellitis, postinfectious ataxia, Whipple's disease, meningoencephalitis, and progressive multifocal leukoencephalopathy. These disorders are treated with steroids and antibiotics. Recognizing treatable disorders is of paramount importance when dealing with ataxias given that early treatment can prevent permanent neurological sequelae.

CV2/CRMP5-antibody-related Paraneoplastic Neurologic Syndrome Associated with Gastrointestinal Stromal Tumor

Paraneoplastic neurological syndrome (PNS) is a heterogeneous group of neurological disorders caused by immune-mediated inflammatory mechanisms. We herein report a 77-year-old man with CV2/CRMP5-antibody-related PNS associated with a gastrointestinal stromal tumor (GIST). He was admitted for forgetfulness and delusional behavior. His neurological symptoms were subacute, and a whole-body examination revealed a gastric GIST. Serology showed CV2/collapsin response mediator protein (CRMP)-5 antibodies. Partial gastrectomy was performed for the GIST, and the neurological symptoms and serum CV2/CRMP5 antibodies disappeared. No relapse has occurred since the surgery. PNS should be considered in patients with subacute neurological disorders.

MicroRNA 452 regulates ASB8, NOL8, and CDR2 expression in colorectal cancer cells

BACKGROUND

MicroRNAs play important roles in the pathogenesis of human diseases by regulating target gene expression in specific cells or tissues. Previously, we identified microRNA 452 (MIR452), which was specifically up-regulated in early stage human colorectal cancer (CRC) tissue.

OBJECTIVE

The current study aims to identify and verify the target genes of MIR452 associated with CRC.

METHODS

A luciferase reporter system was used to confirm the effect of MIR452 on ASB8, NOL8, and CDR2 expression. The expression levels of MIR452 and the target genes were evaluated by quantitative RT-PCR (qRT-PCR) and western blotting.

RESULTS

We verified the association between MIR452 and three genes, ASB8, NOL8, and CDR2, and showed that their transcripts were down-regulated by MIR452. Up-regulated MIR452 also down-regulated ASB8, NOL8, and CDR2 mRNA and protein levels in CRC cells. CDR2 protein expression was decreased in CRC tissues compared to adjacent non-tumor tissues.

CONCLUSIONS

These results suggest that ASB8, NOL8, and CDR2 were target genes of MIR452 in CRC cells and that up-regulated MIR452 in CRC tissue regulated ASB8, NOL8, and CDR2 expression during colorectal carcinogenesis.

Paraneoplastic cerebellar degeneration: Yo antibody alters mitochondrial calcium buffering capacity

Aim

Neurodegeneration is associated with dysfunction of calcium buffering capacity and thereby sustained cellular and mitochondrial calcium overload. Paraneoplastic cerebellar degeneration (PCD), characterized by progressive Purkinje neurone degeneration following paraneoplastic Yo antibody internalization and binding to cerebellar degeneration‐related protein CDR2 and CDR2L, has been linked to intracellular calcium homeostasis imbalance due to calbindin D_28k malfunction. Therefore, we hypothesized that Yo antibody internalization affects not only calbindin calcium binding capacity, but also calcium‐sensitive mitochondrial‐associated signalling, causing mitochondrial calcium overload and thereby Purkinje neurone death.

Methods

Immunohistochemically, we evaluated cerebellar organotypic slice cultures of rat brains after inducing PCD through the application of Yo antibody‐positive PCD patient sera or purified antibodies against CDR2 and CDR2L how pharmacologically biased mitochondrial signalling affected PCD pathology.

Results

We found that Yo antibody internalization into Purkinje neurons caused depletion of Purkinje neurone calbindin‐immunoreactivity, cannabinoid 1 receptor over‐activation and alterations in the actions of the mitochondria permeability transition pore (MPTP), voltage‐dependent anion channels, reactive oxygen species (ROS) and Na⁺/Ca²⁺ exchangers (NCX). The pathological mechanisms caused by Yo antibody binding to CDR2 or CDR2L differed between the two targets. Yo‐CDR2 binding did not alter the mitochondrial calcium retention capacity, cyclophilin D‐independent opening of MPTP or activity of NCX.

Conclusion

These findings suggest that minimizing intracellular calcium overload toxicity either directly with cyclosporin‐A or indirectly with cannabidiol or the ROS scavenger butylated hydroxytoluene promotes mitochondrial calcium homeostasis and may therefore be used as future neuroprotective therapy for PCD patients.

Expression of the onconeural protein CDR1 in cerebellum and ovarian cancer

Cerebellar degeneration related protein 1 (CDR1) is expressed in the cerebellum, and CDR1 antibodies have been associated with paraneoplastic cerebellar degeneration (PCD). In this study, we examined CDR1 expression in cerebellum and in ovarian and breast tumors, as well as the intracellular localization of CDR1 in cancer cells in culture. CDR1 was strongly expressed in the cytosol and dendrites of Purkinje cells and in interneurons of the molecular layer in cerebellum. CDR1 was also present in ovarian and breast tumors, as well as in ovarian and breast cancer cell lines, but was not present in normal breast or ovarian tissue. In cells overexpressing CDR1, CDR1 localized close to the plasma membrane in a polarized pattern at one edge. CDR1 was strongly expressed on the outer surface, apparently in filopodias or lamellipodias, in cells endogenously expressing CDR1. Overexpression of CDR1 showed a 37 and a 45 kDa band in western blot. The 37-kDa isoform was present in 16 ovarian cancer lysates, while the 45-kDa isoform was only found in three ovarian cancer patients. The presence of CDR1 in ovarian cancer was not associated with PCD. CDR1 antibodies were only found in serum from one patient with PCD and ovarian tumor with metastases. Therefore, CDR1 is probably not a marker for PCD. However, CDR1 may be associated with cell migration and differentiation.

Paraneoplastic syndrome associate with solitary fibrous tumor of pleura

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor and several paraneoplastic syndromes have been related to it. We report the case of a 60-year-old male initially admitted to rule out cerebral vascular accident with the final diagnosis of SFT associated with paraneoplastic cerebellar degeneration and hypoglycemia. The diagnosis was confirmed by computed tomography-guided lung biopsy.

A novel thymoma-associated autoimmune disease: Anti-PIT-1 antibody syndrome

Anti-PIT-1 antibody syndrome has recently been reported and characterized by acquired growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies associated with autoimmunity to a pituitary specific transcription factor PIT-1, which plays an essential role in GH-, PRL-, and TSH-producing cells. Although circulating anti-PIT-1 antibody and PIT-1-reactive cytotoxic T cells (CTLs) were detected in the patients, the pathophysiology and precise mechanisms for the autoimmunity remain unclarified. During the follow up, thymoma was diagnosed in all 3 cases with anti-PIT-1 antibody syndrome. Immunohistochemical analysis revealed that PIT-1 was strongly expressed in neoplastic cortical thymic epithelial cells. Importantly, after thymectomy, the titer of anti-PIT-1 antibody decreased and reactivity of CTLs toward PIT-1 diminished. These data strongly suggest that the aberrant expression of PIT-1 in the thymoma plays a causal role in the development of this syndrome. Thus, we define that this syndrome is a novel thymoma-associated autoimmune disease.

Whole-Body 18F-FDG PET and 18F-FDG PET/CT in Patients with Suspected Paraneoplastic Syndrome: A Systematic Review and Meta-Analysis of Diagnostic Accuracy

The purpose of this study was to assess the diagnostic performance of whole-body ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT for detection of underlying malignancy in patients with clinically suspected neurologic and nonneurologic paraneoplastic syndromes. Methods: A systematic search was performed in PubMed (Medline), Embase, and Scopus (last updated November 2016) to identify relevant published studies reporting the performance of ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT in patients with suspected paraneoplastic syndrome. Histopathologic confirmation or clinical follow-up was considered as the reference standard. Pooled estimates, with 95% confidence intervals (CIs), of sensitivity, specificity, and diagnostic odds ratio were calculated. A summary receiver-operating-characteristic curve was constructed, and the area under the curve (AUC) was determined along with the Q* index. Results: Twenty-one studies including a total of 1,293 individual patients suspected of having a paraneoplastic syndrome and who underwent ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT examinations met our inclusion criteria. There was moderate to high heterogeneity among the included studies. The pooled sensitivity, specificity, and diagnostic odds ratio of ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT for the detection of underlying malignancy were 0.81 (95% CI, 0.76-0.86), 0.88 (95% CI, 0.86-0.90), and 34.03 (95% CI, 18.76-61.72), respectively. The AUC and the Q* index were 0.916 (SE, 0.018) and 0.849, indicating excellent diagnostic accuracy. The diagnostic accuracy was slightly improved after studies with high applicability concerns were excluded (AUC, 0.931; SE, 0.020). In a subgroup analysis, ¹⁸F-FDG PET/CT was found to have a significantly higher specificity (0.89 vs. 0.79) than ¹⁸F-FDG PET alone, with no evidence of significant difference in the overall performance (AUC, 0.930 vs. 0.891; 2-tailed P value for difference, 0.31). Conclusion: This meta-analysis of available studies demonstrates that whole-body ¹⁸F-FDG PET or ¹⁸F-FDG PET/CT has high diagnostic accuracy and moderate to high sensitivity and specificity for detection of underlying malignancy in patients suspected of having a paraneoplastic syndrome.

Proteolytic degradation and potential role of onconeural protein cdr2 in neurodegeneration

Cerebellar degeneration-related protein 2 (cdr2) is expressed in the central nervous system, and its ectopic expression in tumor cells of patients with gynecological malignancies elicits immune responses by cdr2-specific autoantibodies and T lymphocytes, leading to neurological symptoms. However, little is known about the regulation and function of cdr2 in neurodegenerative diseases. Because we found that cdr2 is highly expressed in the midbrain, we investigated the role of cdr2 in experimental models of Parkinson's disease (PD). We found that cdr2 levels were significantly reduced after stereotaxic injection of 1-methyl-4-phenylpyridinium (MPP(+)) into the striatum. cdr2 levels were also decreased in the brains of post-mortem PD patients. Using primary cultures of mesencephalic neurons and MN9D cells, we confirmed that MPP(+) reduces cdr2 in tyrosine hydroxylase-positive dopaminergic neuronal cells. The MPP(+)-induced decrease of cdr2 was primarily caused by calpain- and ubiquitin proteasome system-mediated degradation, and cotreatment with pharmacological inhibitors of these enzymes or overexpression of calcium-binding protein rendered cells less vulnerable to MPP(+)-mediated cytotoxicity. Consequently, overexpression of cdr2 rescued cells from MPP(+)-induced cytotoxicity, whereas knockdown of cdr2 accelerated toxicity. Collectively, our findings provide insights into the novel regulatory mechanism and potentially protective role of onconeural protein during dopaminergic neurodegeneration.

Paraneoplastic syndrome-associated neuronal antibodies in adult ADHD

A high seroprevalence of Yo antibodies targeting cerebellar Purkinje cells was recently reported in children with attention deficit/hyperactivity disorder (ADHD). We investigated the presence of 8 paraneoplastic neurological syndrome (PNS)-associated antibodies including anti-Yo in 169 adult ADHD patients. No associations between ADHD and serum Yo antibodies or other antibodies associated with PNS were found. However, 10 out of 48 ADHD patient sera analyzed by immunofluorescence presented antibodies targeting cerebellar Purkinje cells. This reactivity probably represents the presence of low levels of antibodies against multiple cellular hitherto unknown antigens with little to no clinical significance.

Paraneoplastic CDR2 and CDR2L antibodies affect Purkinje cell calcium homeostasis

Paraneoplastic cerebellar degeneration (PCD) is characterized by loss of Purkinje cells (PCs) associated with progressive pancerebellar dysfunction in the presence of onconeural Yo antibodies. These antibodies recognize the cerebellar degeneration-related antigens CDR2 and CDR2L. Response to PCD therapy is disappointing due to limited understanding of the neuropathological mechanisms. Here, we report the pathological role of CDR antibodies on the calcium homeostasis in PCs. We developed an antibody-mediated PCD model based on co-incubation of cerebellar organotypic slice culture with human patient serum or rabbit CDR2 and CDR2L antibodies. The CDR antibody-induced pathology was investigated by high-resolution multiphoton imaging and biochemical analysis. Both human and rabbit CDR antibodies were rapidly internalized by PCs and led to reduced immunoreactivity of calbindin D_28K (CB) and L7/Pcp-2 as well as reduced dendritic arborizations in the remaining PCs. Washout of the CDR antibodies partially recovered CB immunoreactivity, suggesting a transient structural change in CB calcium-binding site. We discovered that CDR2 and CB co-immunoprecipitate. Furthermore, the expression levels of voltage-gated calcium channel Cav2.1, protein kinase C gamma and calcium-dependent protease, calpain-2, were increased after CDR antibody internalization. Inhibition of these signaling pathways prevented or attenuated CDR antibody-induced CB and L7/Pcp-2 immunoreactivity loss, morphological changes and increased protein expression. These results signify that CDR antibody internalization causes dysregulation of cell calcium homeostasis. Hence, drugs that modulate these events may represent novel neuroprotective therapies that limit the damaging effects of CDR antibodies and prevent PC neurodegeneration.

Avidity of onconeural antibodies is of clinical relevance

Onconeural antibodies are important in the detection of paraneoplastic neurological syndromes (PNS). The avidity of Hu, Yo, and CRMP5 antibodies from 100 patients was determined by immunoprecipitation (IP), and 13 of the Yo positive sera were also tested by surface plasmon resonance (SPR). There was a significant association between the results from IP and SPR. Yo antibodies had higher avidity than Hu and CRMP5 antibodies, and both high- and low-avidity antibodies were associated with tumors and PNS. High-avidity Yo antibodies were mainly associated with ovarian cancer, whereas high-avidity Hu and CRMP5 antibodies were mainly associated with small-cell lung cancer. Low-avidity CRMP5 and Yo antibodies were less often detected by a commercial line blot than high-avidity antibodies. The failure to detect low-avidity onconeural antibodies may result in under diagnosis of PNS.

Primary lung carcinoid, a rare cause of paraparesis: report of a case and review of the literature

Carcinoids are neuroendocrine tumors mainly involving the gastrointestinal tract, lungs and bronchi. They were considered benign with slow growth, but they can be malignant in a substantial percentage of patients (metastasizing to liver, bones, skin, etc). Endocrine activity results in carcinoid syndrome. Proximal myopathy has been reported in 7% of patients with carcinoid syndrome. Bronchopulmonary and thymic carcinoids producing adrenocorticotropic hormone can cause Cushing's syndrome, a main feature of which is myopathy. There are a few reports of carcinoids associated with paraneoplastic neurological syndromes, including neuropathy. We hereby present an extremely rare case of a primary lung carcinoid presented with paraparesis due to polyneuropathy, and review the relevant literature. To the best of our knowledge there is no similar previous report. Complete resolution of paraparesis after excision of the lung carcinoid suggests paraneoplastic neurological syndrome.

Breast cancer presents with a paraneoplastic neurologic syndrome

BACKGROUND

Paraneoplastic neurologic syndromes (PNS) pose quite an uncommon neurological complication, affecting less than 1% of patients with breast cancer. Nearly one third of these patients lack detectable onconeural antibodies (ONAs), and improvement in neurologic deficits with concomitant cancer treatments is achieved in less than 30% of cases.

CASE PRESENTATION

A 42-year-old, premenopausal woman presented with facial paralysis on the central left side accompanied by a left tongue deviation, an upward vertical nystagmus, moderate spastic paraparesis, dystonic posturing of the left foot, lower limb hyperreflexia and bilateral extensor plantar reflex. After ruling out all other potential neurologic causes, PNS was suspected but no ONAs were found. A PET-CT scan detected increased metabolism in the right breast, as well as an ipsilateral thoracic interpectoral adenopathy. Core biopsy confirmed the presence of an infiltrating duct carcinoma. After breast surgery, the neurologic symptoms disappeared. One week later, the patient was readmitted to the hospital with a bilateral fatigable eyelid ptosis, and two weeks later, there was a noticeable improvement in eyelid ptosis, accompanied by a rapid and progressive development of lower spastic paraparesis. She started adjuvant treatment with chemotherapy with marked clinical and neurological improvement, and by the end of radiotherapy, there were no signs of neurologic impairment.

CONCLUSION

This case study highlights the importance of a high level of vigilance for the detection of PNS, even when ONAs are not detected, as the rapid identification and treatment of the underlying tumor offers the best chance for a full recovery.

Hypopharyngeal paraganglioma with a paraneoplastic neurologic syndrome: a case report

BACKGROUND

We report an extremely rare case of hypopharyngeal paraganglioma that was accompanied by a paraneoplastic neurologic syndrome (PNS).

METHODS

The clinical, radiological, and histopathologic findings of the patient are presented.

RESULTS

A 49-year-old woman presented with a history of progressive asthenia of the lower extremities persisting for 2 months. She also experienced numbness and sensory disturbance of the left lower limbs, 2 epileptic seizures, and constipation during the period. Clinical and radiological evaluations suggested the diagnosis of encephalomyelitis in combination with a left hypopharyngeal mass lesion. The patient underwent surgical excision of the lesion, which subsequently resolved her symptoms. Postoperative pathology was consistent with a paraganglioma. There was no evidence of local recurrence or distant metastasis of the tumor on recent follow-up.

CONCLUSIONS

To the best of our knowledge, our patient represents the third reported case of hypopharyngeal paraganglioma, and the only one to have a paraneoplastic syndrome.

Onconeural antibodies in patients with neurological symptoms: detection and clinical significance

BACKGROUND

Onconeural antibodies are strongly associated with cancer and paraneoplastic neurological syndromes (PNS). Most of these antibodies are well-characterized (antibodies against Hu, Yo, Ri, CRMP5, amphiphysin, Ma2 and Tr) and are in common use for the diagnosis of definite PNS.

MATERIALS AND METHODS

Literature on detection and clinical significance of onconeural antibodies were identified by using relevant search terms in PubMed and reviewed.

CONCLUSIONS

The onconeural antibodies are directed against intracellular antigens and their pathogenic role is still largely unknown. They are highly specific markers of paraneoplastic aetiology in patients with neurological symptoms. Detection of an onconeural antibody in a patient with neurological symptoms should lead to prompt investigation for cancer. However, absence of detectable onconeural antibodies does not exclude the PNS diagnosis. In particular, failure to detect antibodies in patients without classical PNS symptoms may result in less vigorous cancer screening and diagnostic delay. Neuronal antibodies that are directed to synaptic proteins or proteins of the cell membrane are also associated with neurological symptoms, and probably have pathogenic effects. The association between these antibodies and cancer is less robust, and they are usually not included among the onconeural antibodies.

Onconeural antibodies: improved detection and clinical correlations

Onconeural antibodies are found in many patients with paraneoplastic neurological syndromes (PNS) and define the disease as paraneoplastic. The study describes the presence of onconeural antibodies and PNS in 555 patients with neurological symptoms and confirmed cancer within five years, and compares the diagnostic accuracy of different antibody assays (immunoprecipitation, immunofluorescence and immunoblot). Onconeural antibodies were found in 11.9% of the patients by immunoprecipitation, in 7.0% by immunofluorescence and in 6.3% by immunoblot. PNS were present in 81.8% of the cancer patients that were seropositive by immunoprecipitation. Immunofluorescence and immunoblot failed to detect onconeural antibodies in almost one third of the PNS cases.

CDR2 antigen and Yo antibodies

Paraneoplastic cerebellar degeneration (PCD) is often associated with Yo antibodies that are directed against human cerebellar degeneration-related protein 2 (CDR2). Such antibodies may also be found in ovarian cancer patients without PCD. We studied if there was an association between Yo antibody production and differences in CDR2 cDNA sequence, mRNA or CDR2 expression in ovarian cancers. We found similar CDR2 cDNA sequence, mRNA and protein levels in primary ovarian cancers, with or without associated Yo antibodies. CDR2 was also present in other cancers, as well as in normal ovary tissue. The results suggest that Yo antibodies are not only related to the expression of CDR2 alone, but also to immune dysregulation.

[Paraneoplastic neurological syndromes with reference to anti-neuronal autoantibodies]

Paraneoplastic neurological syndromes (PNS) are thought to be caused by autoimmune processes triggered by the cancer and directed against antigens common to both the cancer and nervous system. There are several clinical phenotypes in combinations with the neurological syndromes, origin of cancer and the specific autoantibodies. In most patients, the neurological disorder develops before the cancer becomes clinically overt together with autoantibodies. As these antibodies are associated with a restricted range of cancers, the presence of the antibodies requires physicians in charge to search the underlying cancers. The early cancer treatment and active immunotherapy tended to ameliorate the neurological symptoms, especially in those harboring antibodies against cell surface antigens like NMDAR. VGKC, VGCC. The group of PNS having antibodies against intracellular antigens might be caused via cytotoxic T cell activation.

Protective and detrimental immunity: lessons from stiff person syndrome and multiple sclerosis

BACKGROUND

The immune system may attack the brain and cause inflammatory disorders like multiple sclerosis (MS). On the other hand, the immune system may protect and support neurons.

METHODS

There are two obstacles to study this paradox in humans. First, the target antigens in many human central nervous system (CNS) disorders are unknown. Second, it is often difficult to separate pathogenic from protective events, as well as primary from secondary phenomena. Idiopathic stiff person syndrome (SPS) circumvents the first obstacle, because most patients secrete antibodies against glutamic acid decarboxylase (GAD) 65. The immune response against glatiramer acetate (GA) may circumvent the second obstacle. Migration of activated T helper cells to the intrathecal compartment could be a common denominator in GA treatment and SPS.

RESULTS

We here discuss recent results on T cells in MS and SPS, showing that GAD65-specific and GA-reactive lymphocytes in the cerebrospinal fluid are not a simple reflection of those in blood.

CONCLUSION

The rules and mechanisms governing T cell selection and maintenance in the CNS may provide a key to the understanding of protective and detrimental aspects of CNS immunity.

[Paraneoplastic neurological syndromes]

BACKGROUND

Paraneoplastic neurological syndromes constitute a heterogenous group of diseases, which often cause severe neurological symptoms. Extensive research during the last 20 years has led to identification of new antigenic targets and inclusion of additional clinical conditions into this group of syndromes.

MATERIAL AND METHODS

The article is based on a non-systematic search of PubMed and the author's own experience with antibody analysis, treatment of patients and research within the field.

RESULTS AND INTERPRETATION

Paraneoplastic neurological syndromes affect less than 1 % of all patients with cancer. The etiology is probably autoimmune, and involves immune responses (cellular and humoral) against antigens shared by tumor cells and normal neurons. Many, but not all patients harbour onconeural antibodies (in serum and spinal fluid), which are highly useful diagnostic markers for a paraneoplastic etiology. The cornerstone of therapy is treatment of the underlying tumor, but additional immunosuppressive therapy is often administered.