Serum cytokine patterns in immunoglobulin m monoclonal gammopathy-associated polyneuropathy.

INTRODUCTION: Polyneuropathy with immunoglobulin M monoclonal gammopathy (IgM-PNP) is associated with the presence of IgM antibodies against nerve constituents such as myelin associated glycoprotein (MAG) and gangliosides. METHODS: To test whether B-cell-stimulating cytokines are increased in IgM-PNP, we measured serum concentrations of 11 cytokines in 81 patients with IgM-PNP and 113 controls. RESULTS: Median interleukin (IL)-6 concentrations were higher in patients with IgM-PNP, and median IL-10 concentrations were higher in the subgroup with anti-MAG IgM antibodies. These serum concentrations were not increased in 110 patients with multifocal motor neuropathy. DISCUSSION: Median IL-6 and IL-10 serum concentrations differ between patients with anti-MAG neuropathy and other patients with IgM-PNP compared with healthy and neuropathy controls. These differences may indicate differences in immune-mediated disease mechanisms. Muscle Nerve 59:694-698, 2019.

Multilaboratory Comparison of Pneumococcal Multiplex Immunoassays Used in Immunosurveillance of Streptococcus pneumoniae across Europe.

Surveillance studies are required to estimate the impact of pneumococcal vaccination in both children and the elderly across Europe. The World Health Organization (WHO) recommends use of enzyme immunoassays (EIAs) as standard methods for immune surveillance of pneumococcal antibodies. However, as levels of antibodies to multiple serotypes are monitored in thousands of samples, a need for a less laborious and more flexible method has evolved. Fluorescent-bead-based multiplex immunoassays (MIAs) are suitable for this purpose. An increasing number of public health and diagnostic laboratories use MIAs, although the method is not standardized and no international quality assessment scheme exists. The EU Pneumo Multiplex Assay Consortium was initiated in 2013 to advance harmonization of MIAs and to create an international quality assessment scheme. In a multilaboratory comparison organized by the consortium, agreement among nine laboratories that used their own optimized MIA was assessed on a panel of 15 reference sera for 13 pneumococcal serotypes with the new WHO standard 007sp. Agreement was assessed in terms of assay accuracy, reproducibility, repeatability, precision, and bias. The results indicate that the evaluated MIAs are robust and reproducible for measurement of vaccine-induced antibody responses. However, some serotype-specific variability in the results was observed in comparisons of polysaccharides from different sources and of different conjugation methods, especially for serotype 4. On the basis of the results, the consortium has contributed to the harmonization of MIA protocols to improve reliability of immune surveillance of Streptococcus pneumoniaeIMPORTANCE Serology of Streptococcus pneumoniae is challenging due to existence of multiple clinically relevant serotypes and the introduction of multivalent vaccines in national immunization programs. Multiplex immunoassays (MIAs) are applied as high-throughput cost-effective methods for serosurveillance, and yet laboratories use their own protocols. The aims of this study were to assess the agreement of results generated by MIAs in different laboratories within the EU Pneumo Multiplex Assay Consortium, to analyze factors contributing to differences in outcome, and to create a harmonized protocol. The study demonstrated good agreement of results of MIAs performed by laboratories using controlled assays for determination of levels of vaccine-induced pneumococcal antibodies. The EU Pneumo Multiplex Assay Consortium is open to everyone working in public health services, and it aims to facilitate efforts by participants to run and maintain a cost-effective, reproducible, high-quality MIA platform.

Coding and non-coding polymorphisms in the lectin pathway activator L-ficolin gene in 188 Dutch blood bank donors.

Human L-ficolin (FCN) is a serum lectin characterized by a collagen-like and a fibrinogen-like domain that can activate the lectin pathway of complement. Structural and functional similarities to mannose-binding lectin (MBL) suggest a role for L-ficolin in innate immunity. Structural polymorphisms in the MBL2 gene lead to functional deficiency of MBL. Polymorphisms in the FCN2 gene have not been studied previously. We developed 10 denaturing gradient gel electrophoresis (DGGE) assays to screen a total of 188 Dutch Caucasians for polymorphisms in FCN2. Total gene screening in this large cohort revealed 10 single nucleotide polymorphisms (SNPs). Interestingly, two conserved coding SNPs were found in exon 8, leading to amino acid substitutions within the fibrinogen-like domain. Fibrinogen-like domains are highly conserved among several proteins in many species. As this domain is responsible for binding of L-ficolin, these newly found coding polymorphisms could alter the affinity of the protein for its substrates and possibly alter the ability of L-ficolin to recognize invading microorganisms.

Classical and lectin complement pathway activity in polyneuropathy associated with IgM monoclonal gammopathy.

Polyneuropathy associated with IgM monoclonal gammopathy (IgM-PNP) is a slowly progressive, sensorimotor neuropathy. It is assumed that complement activation contributes to IgM-PNP pathogenesis. We investigated whether innate differences in complement activity of the classical and mannose binding lectin (MBL) pathways are associated with IgM-PNP or its severity. We measured complement activity using ELISA and determined MBL serumc oncentrations and MBL gene polymorphisms in 83 patients and 83 healthy controls. We did not observe differences between IgM-PNP patients and healthy controls nor associations with different disease severities. Differences in innate complement activity are not likely to explain susceptibility to or severity of IgM-PNP.

Hemolytic assay for the measurement of functional human mannose-binding lectin: a modification to avoid interference from classical pathway activation.

Diagnostic assays for measurement of functional mannose-binding lectin (MBL) in serum are widely performed as part of immune status assessment. Classical pathway mediated complement activity can interfere in these functional MBL assays. Here we describe classical pathway interference incidentally occurring in a previously described hemolytic MBL assay and the modification of this assay to prevent this artifact by addition of anti-C1q antibodies. Classical pathway interference in functional MBL assays can and should be inhibited to prevent that MBL deficiency is overlooked and patients are misdiagnosed.

Deficient mannose-binding lectin-mediated complement activation despite mannose-binding lectin-sufficient genotypes in an outbreak of Legionella pneumophila pneumonia.

Polymorphisms leading to deficiency of mannose-binding lectin (MBL) are associated with predisposition to infection. However, MBL deficiency can be protective against intracellular pathogens that use MBL to enter host cells. The role of MBL genotype and activity in infection with the intracellular pathogen Legionella pneumophila was studied in a large outbreak of legionellosis at a Dutch flower show. A total of 141 patients, 65 exposed asymptomatic exhibition staff members and 670 unexposed blood bank donors were included for the study of MBL2 genotypes and MBL-mediated complement activation. Genotypic MBL deficiency was equally prevalent in patients and controls. Deficient MBL-mediated complement activation was more prevalent in patients. Even in patients with genotypes that confer MBL sufficiency, 20.6% lacked MBL-mediated complement activation. In most patients with MBL-sufficient genotypes who lacked MBL-mediated activation at the acute phase of disease, lectin pathway functionality was restored at convalescence. In conclusion, genotypic MBL deficiency was not a risk factor for legionellosis. However, patients with legionellosis displayed deficient MBL-mediated complement activation even with MBL-sufficient genotypes. Together, these genotypical and functional data suggest that the observed deficiency of lectin pathway activation is an effect of legionellosis rather than a risk factor for acquiring it.

Mannose-binding lectin genotypes in susceptibility to community-acquired pneumonia.

BACKGROUND: Community-acquired pneumonia (CAP) is most frequently caused by Streptococcus pneumoniae, Haemophilus influenzae, atypical pathogens, and respiratory viruses. Susceptibility to CAP can be increased by single-nucleotide polymorphisms (SNPs) within the mannose-binding lectin (MBL) gene. We questioned whether MBL polymorphisms are associated with the susceptibility to and outcome of CAP and its most common pathogens. METHODS: All adult patients presenting with CAP in a 23-month period were included in this study. Frequencies of SNPs were determined for the promoter X/Y and the three coding SNPs in exon 1 (A/0). Six genotypes were constructed representing patients with sufficient and deficient serum levels of MBL. The results of the patients with CAP were compared with control subjects. RESULTS: In 199 patients and 223 control subjects, MBL genotypes were determined. There were no differences in MBL genotype frequencies between patients with CAP in general, pneumonia caused by S pneumoniae or H influenzae, and control subjects. The frequency of sufficient MBL genotypes was nonsignificantly higher in patients with pneumonia with Legionella sp and Mycoplasma pneumoniae. In Legionella spp, the sufficient YA/YA genotype was significantly more frequent than in control subjects (odds ratio [OR], 5.43; confidence interval [CI], 1.32 to 22.41; p = 0.02). The frequency of the MBL-deficient genotype was significantly higher in patients with viral (co)infections (OR, 2.36; CI, 1.06 to 5.26; p = 0.03) and nonsignificantly higher in patients with pneumococcal pneumonia and viral (co)infections. MBL genotypes had no effect on outcome. CONCLUSIONS: MBL genotypes play a limited role in pneumococcal pneumonia. Sufficient MBL genotypes were more frequently found in a small group of patients with atypical pneumonia, and MBL-deficient genotypes were more frequently found in patients with viral (co)infections.

Antibodies against cyclic citrullinated peptide and IgA rheumatoid factor predict the development of rheumatoid arthritis.

OBJECTIVE: To evaluate the prevalence and predictive value of anti-cyclic citrullinated peptide (anti-CCP) antibodies in individuals who subsequently developed rheumatoid arthritis (RA) and to determine the relationship to rheumatoid factor (RF) of any isotype. METHODS: A case-control study was nested within the Northern Sweden Health and Disease Study and the Maternity cohorts of Northern Sweden. Patients with RA were identified among blood donors whose samples had been taken years before the onset of symptoms. Control subjects matched for age, sex, date of sampling, and residential area were selected randomly from the same cohorts. Anti-CCP antibody and RFs were determined using enzyme immunoassays. RESULTS: Eighty-three individuals with RA were identified as having donated blood before presenting with any symptoms of joint disease (median 2.5 years [interquartile range 1.1-4.7] before RA). In samples obtained before the onset of RA, the prevalence of autoantibodies was 33.7% for anti-CCP, 16.9% for IgG-RF, 19.3% for IgM-RF, and 33.7% for IgA-RF (all highly significant compared with controls). The sensitivities for detecting these autoantibodies >1.5 years and