Susceptibility to demyelinating polyneuropathy in plasma cell dyscrasia may be influenced by amino acid position 9 of the HLA-DR beta chain

Myelin protein zero is naturally processed in the B cells of monoclonal gammopathy of undetermined significance of immunoglobulin M isotype: aberrant triggering of a patient's T cells

BACKGROUND

Monoclonal gammopathy of undetermined significance of immunoglobulin M isotype is a condition with clonally expanded B cells, recently suggested to have an infectious origin. This monoclonal gammopathy is frequently associated with polyneuropathy and antibodies against myelin protein zero, whereas the role of the T cells remains largely unknown. We analyzed protein zero-specific B cells, as antigen-presenting cells, and their capacity to activate T helper cells.

DESIGN AND METHODS

We used a well-characterized monoclonal gammopathy of undetermined significance-derived B-cell line, TJ2, expressing anti-protein zero immunoglobulin M. The ability of TJ2 cells to bind, endocytose, process, and present protein zero was investigated by receptor-clustering and immunofluorescence. The activation of protein zero-specific autologous T cells was studied by measuring interleukin-2 and interferon-gamma with flow cytometry, immunobeads, and enzyme-linked immunospot assays.

RESULTS

Surface-receptor clustering and endocytosis of receptor-ligand (immunoglobulin M/protein zero) complexes were pronounced after exposure to protein zero. Naturally processed or synthetic protein zero peptide (194-208)-pulsed TJ2 cells significantly induced interleukin-2 secretion from autologous T cells compared to control antigen-pulsed cells (P<0.001). The numbers of interferon-gamma-producing T helper cells, including CD4(+)/CD8(+) cells, were also significantly increased (P=0.0152). Affinity-isolated naturally processed myelin peptides were potent interferon-gamma stimulators for autologous peripheral blood mononuclear cells, but not for control peripheral blood mononuclear cells.

CONCLUSIONS

We show for the first time that myelin protein zero is naturally processed in B cells from monoclonal gammopathy of undetermined significance of immunoglobulin M isotype, acting as aberrant antigen-presenting cells in activation of a patient's T helper cells. Our findings cast new light on the important role of autoreactive protein zero-specific B cells in the induction of the pathogenic T-cell responses found in nerve lesions of patients with monoclonal gammopathy of undetermined significance with peripheral neuropathy.

Association of acute parvovirus B19 infection with new onset of acute lymphoblastic and myeloblastic leukaemia

AIMS

To investigate the association of acute parvovirus B19 infection with new onset of acute lymphoblastic and myeloblastic leukaemia.

METHODS

Cerebrospinal fluid (CSF) samples from patients with acute myelogenous leukaemia (AML) at diagnosis (n = 2) and acute lymphoblastic leukaemia (ALL) at diagnosis (n = 14) were analysed for parvovirus B19 DNA by means of nested polymerase chain reaction. In addition, samples from patients with benign intracranial hypertension (BIH) (n = 10) and hydrocephalus (n = 13) were tested as controls.

RESULTS

Four leukaemia cases were positive-common ALL (n = 2), null cell ALL (n =1), and M7 AML (n = 1)-whereas all controls were negative (Yates corrected chi(2) value, 3.97; p = 0.046; odds ratio, 16.92; confidence interval, 1.03 to 77.18). All four patients were significantly anaemic, but none was encephalitic or had evidence of central nervous system leukaemia. In three of these patients, serum tumour necrosis alpha, interferon gamma, interleukin 6, granulocyte-macrophage colony stimulating factor (range, 34.93-3800.06 pg/ml), and macrophage chemoattractant protein 1 were detectable. All of these four patients carried at least one of the HLA-DRB1 alleles, which have been associated with symptomatic parvovirus B19 infection.

CONCLUSION

Erythroid suppression and immune cell proliferation are both associated with B19 infection and may also be important in the pathogenesis of acute leukaemia.

Evidence for the role of demyelination, HLA-DR alleles, and cytokines in the pathogenesis of parvovirus B19 meningoencephalitis and its sequelae

OBJECTIVE

To review the clinical and pathological features of parvovirus B19 meningoencephalitis and its sequelae in 12 previously published cases, and to perform additional tests to determine the pathogenesis of the disease.

METHODS

Cases were reviewed and available serum and cerebrospinal fluid (CSF) tested for antiganglioside antibodies and a range of cytokines. In situ hybridisation for parvovirus B19 DNA was performed on postmortem brain tissue in two cases. HLA-DRB1 typing was undertaken on genomic DNA extracted from peripheral blood leucocytes.

RESULTS

Cerebellar involvement was suggested either clinically or pathologically in four cases. In the two cases with postmortem histology, there was marked atrophy of the molecular and granular layers of the cerebellum with focal loss of Purkinje cells. Brain scanning by MRI or CT was done in six cases during the acute phase. Three were abnormal with evidence of demyelination. Three had markedly enlarged ventricles, in two of which there was high signal intensity from the white matter on both T1 and T2 weighted images. The three cases with abnormal brain scans had long term neurological sequelae (mental retardation, personality change, altered affect). In situ hybridisation on available postmortem brain tissue was negative in the two cases tested. All cases in which HLA-DR alleles were determined carried at least one of the following alleles: HLA-DRB1*01, *04, *07, *09, *15, *16. Available serum and CSF was tested for antiganglioside antibodies (all negative) and for a panel of cytokines, which had a similar profile in both serum (n = 5) and CSF (n = 1) during the acute phase. Cytokines that were consistently detectable were IL-6 (mean 726.20 pg/ml), TNFalpha (50.64 pg/ml), IFNgamma (39.64 pg/ml), GM-CSF (216.12 pg/ml), and MCP-1 (154.43 pg/ml); IL-1beta, IL-5, and IL-13 were undetectable.

CONCLUSIONS

HLA-DR associations, an increased cytokine response, and benefit from immunomodulatory treatment (in one case) support a role for the immune response in the pathogenesis of parvovirus B19 meningoencephalitis.

Cytomegalovirus is not associated with IgM anti-myelin-associated glycoprotein/sulphate-3-glucuronyl paragloboside antibody-associated neuropathy

Monoclonal antibodies reactive with the HNK-1 epitope of myelin-associated glycoprotein (MAG) and the sulphate-3-glucuronyl paragloboside (SGPG)-like glycolipids are often found in the serum of patients with IgM paraprotein-associated demyelinating neuropathy. The presence of such antibodies in patients with chronic polyneuropathy has recently been associated with evidence of active cytomegalovirus (CMV) infection by the polymerase chain reaction. We wished to test these findings and examined sera from patients with MAG-reactive or MAG-nonreactive paraproteinemic neuropathy and patients with paraproteinemia only for the presence of CMV DNA and anti-CMV antibodies. CMV DNA was not detected in sera from any patient group. Furthermore, anti-CMV antibody prevalence was normal and similar in all 3 groups. We therefore report no evidence of an association between CMV infection and anti-MAG/SGPG antibodies associated with paraproteinemic peripheral neuropathy.

Heterogeneity of antibody specificity in Taiwanese patients with polyneuropathy and IgM paraproteinemia

About half of the Caucasian patients with chronic polyneuropathy and IgM paraproteinemia show serum anti-myelin-associated glycoprotein (MAG) and anti-sulfoglucuronosyl glycosphingolipid (SGGLs) activities. These antibody activities have been demonstrated to react with a carbohydrate epitope known as the HNK-1 or sulfoglucuronic acid (SGA) epitope. However, in Asian populations the occurrence of serum anti-SGA activities has been reported to be relatively rare. We investigated 5 cases of chronic polyneuropathy with IgM paraproteinemia from Taiwan and found that 3 of them had high-titer serum anti-SGA (SGGL/MAG) antibody activities. The clinical symptoms of these 3 patients were consistent with sensory dominant polyneuropathy with a severer involvement of the lower limbs than of the upper limbs. Electromyography and nerve conduction studies revealed severe sensory nerve involvement (no response in 3 cases) and moderate slowing of motor conduction velocity (MCV) without conduction block. The decrease in MCV correlated well with anti-SGA antibody titer (less than 30 m/s with the titration of 1:12, 800, normal 55-60 m/s). Pathological findings showed active demyelinating polyneuropathy with myelin ovoid and myelinated fiber loss. Our data suggest that anti-SGGL antibody activities may not be very rare among Asian populations. Additionally, there seems an intriguing possibility that the titer of this antibody correlates with the severity of peripheral nerve involvement in patients of demyelinating polyneuropathy with IgM paraproteinemia.

Neuropathy associated with "benign" anti-myelin-associated glycoprotein IgM gammopathy: clinical, immunological, neurophysiological pathological findings and response to treatment in 33 cases

We studied 33 patients presenting with a peripheral neuropathy associated with non-malignant anti-myelin-associated glycoprotein (MAG) IgM monoclonal gammopathy (MG) in an attempt to delineate their clinical, immunological, electrophysiological and pathological characteristics; we also reviewed our experience concerning long-term follow-up and therapy. Peripheral neuropathy associated with non-malignant anti-MAG IgM MG was observed mostly in males (sex ratio 7.2), and mean age at onset was 67 years (range 46-81). A predominantly sensory pattern was noted in more than 80% of cases, although some patients were affected by a predominantly motor peripheral neuropathy. Although disease progression was slow in most cases, 45% of patients suffered severe disability, and in 2 cases, the patient's death appeared to stem directly from the neuropathy. The electrophysiological findings were indicative of a demyelinating process in 90% of cases, and electron microscopic examination of nerve biopsy specimens demonstrated widening of the myelin lamellae in more than 95% of cases. Most of our patients showed a disappointing response to steroids and chemotherapy or plasma exchanges. Intravenous immune globulin, evaluated in 17 patients, had a transient, mostly subjective effect in 35% and led to a clear-cut improvement in 24% of cases. We did not observe any correlation between the severity of the clinical picture and the anti-sulphoglucuronyl paragloboside antibody titre; in individual cases, clinical improvement occurred without lowering of IgM levels. Although the severity and the rate of progression may greatly vary from patient to patient, the combination of clinical, electrophysiological and pathological features delineates a characteristic pattern in peripheral neuropathy associated with non-malignant anti-MAG IgM MG.

Somatically mutated member of the human V lambda VIII gene family encodes anti-myelin-associated glycoprotein (MAG) activity

A highly conserved small family of human V lambda genes was identified by DNA homology to a V lambda gene isolated from a patient with demyelinating peripheral neuropathy, and which encodes an autoantibody with anti-MAG activity. Comparison of the genes indicates that the patient V lambda gene was derived from one of the germline genes. Together with published analyses of other anti-MAG IgM antibodies, which also appear to be mutated in comparison to known germline V genes, these results suggest that development of these pathogenic antibodies may reflect an antigen-driven, T cell-dependent process.

Abnormalities in T-lymphocyte populations in blood from patients with demyelinating polyneuropathy associated with monoclonal gammopathy

Patients with monoclonal gammopathy secrete monoclonal antibodies (M-component), that in some patients are associated with polyneuropathy. The M-component has been shown to react with peripheral nerve myelin in some of these patients. However, it is not known whether the M-component secreting B-cells are autonomous or subject to regulation by T-cells or if other cellular abnormalities may occur. In order to define circulating lymphocyte subpopulations, flow cytometry was done on blood samples from patients with monoclonal gammopathy and demyelinating polyneuropathy (n = 13) and patients with monoclonal gammopathy without polyneuropathy (n = 11), and were compared to healthy controls. Significantly increased proportions of primed T-helper (CD4+) cells, i.e. those expressing helper/inducer function (CD29+ CD4+), providing help for antibody secretion, as well as decreased proportions of naive, unprimed suppressor/inducer (CD45RA+ CD4+) T-helper cells were found in patients with M-component associated polyneuropathy. Within the T-cytotoxic/suppressor population (CD8+) we found an increased proportion of killer/effector (S6F1+ CD8+) cells and a decreased proportion of suppressor/effector (S6F1- CD8+) cells in patients with monoclonal gammopathy and polyneuropathy. Similar findings were found in monoclonal gammopathy patients without polyneuropathy, although the deviations in general were less pronounced and did not reach statistical significance compared to the controls. The proportion of natural killer (NK) cells (CD56+) was markedly decreased in all patients with monoclonal gammopathy. In the whole group of patients with monoclonal gammopathy, we found clear proportions of interleukin-2 receptor (CD25+) expressing lymphocytes, indicating the presence of activated T-cells. No clear correlation between abberations in T-cell subtypes and clinical severity of the demyelinating polyneuropathy or titres of anti-PNM antibodies was found.(ABSTRACT TRUNCATED AT 250 WORDS)