Detection and isolation of immune complexes in multiple sclerosis cerebrospinal fluid

A proteomics-based method for identifying antigens within immune complexes

A novel approach to recover and identify immune complexes (ICs) was developed using size exclusion chromatography (SEC) and affinity chromatography on immunoglobulin binding columns (HiTrap Protein G). The purification process was monitored by 1D SDS-PAGE, protein staining, Western blotting and, finally, liquid chromatography tandem mass spectrometry (LC MS/MS) was used to identify the recovered antigens. This approach was applied to serum with artificially created immune complexes (ICs) comprising vaccine antigen (influenza) and antibody, which led to recovery and identification of influenza peptides within the recovered ICs. This approach was compared with the established method for IC detection and recovery, polyethylene glycol (PEG) precipitation, followed by LC MS/MS. Both approaches successfully enabled capture, recovery and characterization of immunoglobulins and influenza antigen(s) in complex with the immunoglobulins. However, PEG precipitation has the advantage of simplicity and is more suited for large scale studies.

Women who contributed to past research in multiple sclerosis

BACKGROUND

The history of multiple sclerosis (MS) is dominated by the discoveries of famous men. However, women would like to feel part of the story and to know that women have contributed to MS research.

OBJECTIVE

To identify women who contributed to the history of discovery in MS.

METHOD

This was a personal survey from my knowledge of previous work.

RESULTS

There were no women participants in the early stages of MS research. However, since 1950 there are many women who have contributed to MS research. In the 20th century, there were famous women who contributed to the scientific fields that form the basis of MS research. In the 21st century, more women participate in MS research but studies suggest that they are under-represented in positions of prominence.

CONCLUSION

Women have been part of the effort to understand MS, but are not well recognized.

Proteomic approach to profiling immune complex antigens in cerebrospinal fluid samples from patients with central nervous system autoimmune diseases

BACKGROUND

Immune complexes (ICs) may clearly reflect immunological abnormalities caused by disease, especially for autoimmune diseases. Although ICs have been detected in cerebrospinal fluid (CSF) from patients with CNS autoimmune diseases, identities of antigens in such ICs have not been comprehensively determined.

METHODS

We used immune complexome analysis, in which nano-liquid chromatography-tandem mass spectrometry is employed to comprehensively identify antigens incorporated into ICs in biological fluids, to characterize ICs in CSF samples from patients with CNS autoimmune diseases, and to find disease-specific IC antigen to a certain CNS autoimmune disease. Also, we compared the IC antigens we identified with the reported CSF proteome or with the published plasma proteome to examine if the method is distinguished from the conventional CSF proteome analysis.

RESULTS

We identified 176 antigens in 78 CSF samples. We then assessed the overlaps among these antigens, the CSF proteome, and the plasma proteome; 140 of the 176 antigens were found to be exclusively detected by our method. Notably, IC-associated suprabasin in CSF was 100% specific to neuropsychiatric systemic lupus erythematosus (NPSLE).

CONCLUSIONS

This report is the first to comprehensively identify the antigens incorporated into ICs in CSF. There was limited overlap between the antigens we identified and the CSF proteome or the plasma proteome; therefore, our method can be distinguished from the conventional CSF proteome analysis. Although the sensitivity of disease-specific IC-antigens detected in immune complexome analysis screening, the sensitivity may be improved by developing an ELISA method specifically for detecting the ICs. Immune complexome analysis of CSF may be a new and promising path to biomarker discovery for diagnosis and study for CNS autoimmune diseases.

Cerebrospinal fluid T cell clones from patients with multiple sclerosis: recognition of idiotopes on monoclonal IgG secreted by autologous cerebrospinal fluid B cells

Due to somatic recombination and hypermutation, Ig variable heavy (V(H)) and light (V(L)) regions contain unique immunogenic determinants, idiotopes (Id), which can stimulate T cells. To address the relevance of this in a human disease, monoclonal IgG (mAb)-secreting B cell clones were established from the cerebrospinal fluid (CSF) of two patients with multiple sclerosis (MS). HLA-DR-restricted CD4(+) T cell lines and clones from CSF of both patients specifically recognized autologous CSF mAb. The CSF T cell clones produced IFN-gamma; some also produced TNF-alpha, IL-10 and IL-5. V(H) and V(L) on the monoclonal IgG derived from CSF B cells expressed amino acid replacements due to somatic mutations. A T cell epitope was mapped to a V(H) framework region, where an amino acid replacement was critical for the T cell recognition. The finding of Id-specific T cells and Id-bearing B cells in the CSF indicates that they coexist within the diseased organ, and provide a basis for the study of Id-driven T-B cell collaboration in a human autoimmune disease.

New method for detection of Borrelia burgdorferi antigen complexed to antibody in seronegative Lyme disease

Serologic tests for Lyme disease are problematic. Because of cross-reactive antigens Borrelia burgdorferi (Bb) shares with other organisms, Lyme disease can be overdiagnosed. However, in addition to specificity problems, serologic tests for early Lyme disease can be falsely negative due to lack of sensitivity of ELISAs and Western blots. Most routine antibody tests are designed to detect free antibodies, and in early, active disease, circulating antibodies may not be free in serum but sequestered in complexes with the antigens which originally triggered their production. This difficulty may be overcome by first isolating immune complexes (IC) from the serum and using this fraction for testing. Free Borrelia-specific antibodies can then be liberated from the immune complexes which may enhance test sensitivity in patients with active disease. We developed a technique that captures the antibody component of IC on immunobeads, and subsequently releases the antigen component of IC. Immunoblotting with monoclonal antibody detected at least one antigen to be OspA, thus definitively demonstrating a Borrelia-specific antigen in circulating IC in early Lyme disease. This test is also useful in demonstrating Bb antigen in otherwise seronegative Lyme disease patients.

Bullous pemphigoid and multiple sclerosis: a report of three cases and review of the literature

Three patients with longstanding multiple sclerosis (MS) who developed bullous pemphigoid (BP) are reported. All patients had immunological features of typical BP as determined by immunofluorescence and Western immunoblotting studies. The clinical features, however, differed from those observed in typical BP. In two the BP started near an indwelling catheter and two had striking involvement of the soles. None of our patients, or a further nine cases reported in the literature, had mucous membrane involvement. In MS patients BP appears to develop at a younger age. Multiple drugs were taken by the MS patients; these, however, appear not to play a role in triggering their BP. The course of BP in patients with MS is moderate, although the majority require systemic treatment.

Seric immune complexes in multiple sclerosis do not contain MBP epitopes

Immune complexes from sera of MS patients, other neurological diseases, and healthy donors were precipitated using polyethyleneglycol and analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis. Silver staining evidenced additional protein bands whose molecular weights were 14-16, 38, and 43 kDa. These IC proteins were present in most MS patients studied. To identify their nature, immunoblotting was performed with antihuman immunoglobulins A, M, G antibodies. No immunoreactivity was found below a molecular weight of 66 kDa on a nitrocellulose sheet having the transferred protein pattern of MS IC. Using purified human myelin, MS IC transferred to an immobilon sheet and antihuman myelin basic protein antibodies, an immunoreactivity was seen only on purified human MBP. The small proteins of 14-16 kDa and the others of 38, 43 kDa were not immunoreactive. Identification of the nature of these additional proteins in MS IC is in progress.

Analysis of cerebrospinal fluid proteins by electrophoresis

The cerebrospinal fluid (CSF) is a specific ultrafiltrate of plasma, which surrounds the brain and spinal cord. The study of its proteins and their alteration may yield useful information on several neurological diseases. By using various electrophoretic separation techniques, several CSF proteins have been identified derived from plasma or from brain. Different one-dimensional methods, such as agarose gel electrophoresis and isoelectric focusing, are of similar value in identifying the non-specific oligoclonal bands, which are mainly helpful in the diagnosis of multiple sclerosis and other inflammatory diseases. Isoelectric focusing has a greater resolution than other one-dimensional methods, and it yields additional data about disease-associated proteins occurring in Alzheimer's disease, Huntington's chorea and amyotrophic lateral sclerosis. Silver-stained two-dimensional gels provide more information about the complex protein composition of CSF, particularly about proteins produced in the brain, such as apolipoprotein E and neuron-specific enolase. For the detection of oligoclonal antibodies, the investigation of protein changes revealed by Parkinson's disease, schizophrenia and Creutzfeldt-Jakob disease, and the analysis of CSF immune complexes, two-dimensional electrophoresis has a greater sensitivity.

Analysis of circulating immune complexes isolated from plasma, cerebrospinal fluid and urine

The protein nature of soluble immune complexes (IC) from fresh plasma, cerebrospinal fluid (CSF), and urine was studied by combining several analytical and biochemical techniques. In plasma and CSF, free immunoglobulins G were separated from larger IC by gel filtration with a fast protein liquid chromatographic system. In urine, IC were separated by precipitation with polyethylene glycol. IC were further purified by protein-A and protein-G affinity chromatography and analyzed by two-dimensional gel electrophoresis. Apart from plasma samples from healthy donors, IC from cases with macrocreatine kinase type 1 and multiple sclerosis were analyzed. For CSF two cases of multiple sclerosis and for urine one case with urinary tract infection are shown. The method can be used for the examination of IC of unknown protein composition in body fluids.

Cerebrospinal fluid immune complexes in patients exposed to Borrelia burgdorferi: detection of Borrelia-specific and -nonspecific complexes

We analyzed cerebrospinal fluid (CSF) from 32 patients with neurological symptoms and evidence of Borrelia burgdorferi infection (29 were seropositive as determined by enzyme-linked immunosorbent assay, 2 were cell-mediated immune positive, and 1 had been seropositive as shown by enzyme-linked immunosorbent assay 9 months previously). CSF immune complexes were found in 22 (69%) of 32 patients; in 18, there was sufficient sample to isolate immune complexes. By enzyme-linked immunosorbent assay, isolated immune complexes from 10 of these 18 patients contained antibody specific for B. burgdorferi antigens. The isotypes were IgG (n = 8), IgM (n = 3), and IgA (n = 2). By immunoblot, these antibodies were directed against B. burgdorferi 41-kDa antigen and occasionally against the 33- and 17-kDa antigens. Anti-B. burgdorferi IgM was present in patients with acute neurological symptoms, was predominantly complexed rather than free, and decreased with clinical recovery in the one serial study. Three patients were nonreactive for free CSF antibodies, but had complexed antibodies to the organism. The preliminary finding of specific B. burgdorferi components in immune complexes in CSF suggests an active process triggered by the organism, even in the absence of other CSF abnormalities.

Sequestration of antibody to Borrelia burgdorferi in immune complexes in seronegative Lyme disease

To find out whether apparent seronegativity in patients strongly suspected of having Lyme disease can be due to sequestration of antibodies in immune complexes, such complexes were isolated and tested for antibody to Borrelia burgdorferi. In a blinded analysis the antibody was detected in all 10 seronegative Lyme disease patients with erythema chronicum migrans (ECM), in none of 19 patients with other diseases, and in 4 of 12 seronegative patients who probably had Lyme disease but had no ECM. These findings were confirmed by western blot, which also showed that immune complex dissociation liberated mainly antibody reactive to the 41 kD antigen and sometimes antibody to an approximate 30 kD antigen. Complexed B burgdorferi antibody was also found in 21 of 22 (95%) of seropositive patients with active disease, 3 additional seronegative but cell mediated immune reactive patients, and 3 other seronegative patients who eventually became seropositive. Apparent B burgdorferi seronegativity in serum immune complexes may thus be due to sequestration of antibody in immune complexes.

Analysis of immune complexes of cerebrospinal fluid by two-dimensional gel electrophoresis

From the cerebrospinal fluid of 32 patients with different neurological diseases immune complexes were isolated using protein A-Sepharose. The isolated heavy and light chains and their constituents were analyzed by two-dimensional gel electrophoresis. In addition to immunoglobulins, some proteins such as albumin, apolipoprotein A-I and a number of unknown proteins were detected in all preparations. A complex consisting of three proteins with molecular masses between 52-55 kDa reacted slightly with polyclonal antibodies to glial fibrillary acidic protein. Whether the linkage between these antigens and the Ig is due to the Fab region or the Fc region remains unknown in our study. In some immune complexes of neurological diseases such as amyotrophic lateral sclerosis, astrocytoma and multiple sclerosis, differences are easily recognizable in the gel pattern.