Affinity immunoblotting: rapid and sensitive detection of oligoclonal IgG, IgA and IgM in unconcentrated CSF by agarose isoelectric focusing

Detection of oligoclonal IgG kappa and IgG lambda bands in cerebrospinal fluid and serum with Hevylite™ antibodies. comparison with the free light chain oligoclonal pattern

Background

Oligoclonal IgG bands in cerebrospinal fluid that are absent in serum indicate intrathecal IgG synthesis and are a sensitive marker of CNS inflammatory diseases, in particular multiple sclerosis. It may be of interest to determine whether these bands are predominantly IgGκ or IgGλ.

Methods

We have used Hevylite™ antibodies and developed a technique for detection of oligoclonal IgGκ and IgGλ bands by means of isoelectric focusing followed by immunoblotting. The same technique was used for oligoclonal free κ and free λ detection. Among several techniques tested, affinity immunoblotting appears to be the most sensitive; it can detect less than 1 ng of IgGκ or IgGλ paraprotein. We compared oligoclonal IgG profiles with those of oligoclonal IgGκ and IgGλ. There was good agreement concerning the presence or absence of intrathecal synthesis. We observed the ratios between oligoclonal IgGκ and IgGλ bands, and they did not always match the ratios between free κ and free λ bands. We were also able to detect antigen-specific CSF-restricted oligoclonal IgGκ and IgGλ bands in neuroborreliosis. It remains to be determined subsequently by a clinically-oriented prospective study, whether predominant IgGκ/IgGλ or free κ/free λ can be observed more frequently in particular diseases with oligoclonal IgG synthesis.

Discussion

Very sensitive detection of oligoclonal IgGκ and IgGλ bands in cerebrospinal fluid with Hevylite antibodies is feasible; detection of antigen-specific IgGκ or IgGλ is possible as well. In particular situations, e.g. when difficulties arise in distinguishing between oligoclonal and monoclonal pattern, the test may be of considerable clinical value.

Qualitative evidence of Ri specific IgG-synthesis in the cerebrospinal fluid from patients with paraneoplastic neurological syndromes

The presence of Ri-specific oligoclonal IgG bands in the CSF was investigated in five patients with paraneoplastic anti-Ri associated neurological syndromes (PNS) and six controls. In 4/5 CSF samples reactivity of IgG bands with recombinant Ri antigen was found using isoelectrofocusing combined with affinity blotting; in one patient with absence of oligoclonal bands of total IgG in CSF Ri-specific oligoclonal bands were detected with the same sample, indicating a higher sensitivity of Ri-specific affinity blotting as compared to affinity blotting with anti-human IgG antibodies. Our results confirm previous studies demonstrating IgG synthesis against onconeuronal antigens by intrathecal B-cell clones in PNS and extend this observation to patients with anti-Ri syndrome. The pathogenic relevance of these antibodies, however, is further challenged by the finding that specific intrathecal IgG synthesis might not be a prerequisite of CNS involvement, because it was missed in one of our patients.

Intrathecal IgM-synthesis does not correlate with the risk of relapse in patients with a primary demyelinating event

The objective of this study was to investigate, whether the presence of oligoclonal immunoglobulin M bands (IgM-OCB) in cerebrospinal fluid (CSF) from patients with a clinically isolated syndrome (CIS), which is suggestive for the first clinical manifestation of multiple sclerosis (MS), anticipates the risk of a relapse during a retrospective study period of 21-106 months (mean 60 +/- 25). A relapse would lead to the diagnosis of clinically definite MS. Paired CSF and serum samples from 42 patients with a CIS and positive intrathecal IgG-synthesis were tested retrospectively for IgM-OCB, which are exclusively present in CSF, but not in the corresponding serum. Isoelectric focusing and affinity blot were used and clinical follow-up was based on telephone interviews. IgM-OCB were found in the CSF from 31 of 42 patients (74%). There was no correlation between the presence of IgM-OCB, the number of such bands or the IgM-Index on the one hand and the risk of a relapse during the follow-up in the cohort studied, on the other hand. These data do not support the idea that the presence of IgM-OCB in CSF might predict an unfavourable course in MS.

Qualitative evidence of anti-Yo-specific intrathecal antibody synthesis in patients with paraneoplastic cerebellar degeneration

We investigated the presence of anti-Yo-specific oligoclonal antibody bands in cerebrospinal fluid (CSF) and serum samples of 9 patients with anti-Yo syndrome and 11 controls. Isoelectric focusing combined with affinity blotting, revealed anti-Yo-specific intrathecal antibody synthesis in all patients with anti-Yo syndrome: Four patients had positive anti-Yo-specific oligoclonal IgG bands in CSF which were not demonstrable in their sera; five CSF/serum pairs showed additional, more intensive, oligoclonal bands in CSF compared to the corresponding serum. Interestingly, four patients with absence of oligoclonal bands of total IgG in CSF revealed positive anti-Yo-specific oligoclonal bands in the same sample. This speaks for a higher sensitivity of detection of oligoclonal bands using an affinity blot loaded with Yo-specific antigen compared to an affinity blot coated with anti-human IgG used for the detection of oligoclonal bands of total IgG. In conclusion, the presence of anti-Yo-specific oligoclonal IgG bands in CSF which were absent, or less strong, in patients sera provides qualitative evidence of anti-Yo-specific IgG synthesis by intrathecal B-cell clones. These results could be of interest in detection of intrathecal-specific IgG synthesis in nervous system infectious diseases provided that the target antigen is known.

A sensitive and reproducible method for the detection of oligoclonal IgM bands

We have developed a sensitive and specific isoelectrofocusing (IEF) method for the detection of oligoclonal (OGC) IgM in the cerebrospinal fluid (CSF) and sera. In this procedure, ampholytes, in the range pH 5-8, were used to improve the resolution, and serum was diluted in saline to avoid IgM precipitation. Samples were treated with 50 mM dithiothreitol (DTT) at pH 9.5 to reduce IgM and improve the migration of the protein. Using an anti-IgM labelled with alkaline phosphatase, the limit of detection was found to be 0.1 ng in 5 microl of sample.

Demonstration of anti-HuD specific oligoclonal bands in the cerebrospinal fluid from patients with paraneoplastic neurological syndromes. Qualitative evidence of anti-HuD specific IgG-synthesis in the central nervous system

The presence of HuD-specific oligoclonal IgG bands in the CSF was investigated in five patients with paraneoplastic neurological syndromes. All patients revealed intrathecal synthesis of HuD specific antibodies in the CSF, as estimated from elevated antibody indices (>1.5) in an IgG-ELISA using recombinant HuD-protein as antigen. Isoelectrofocussing combined with affinity blotting showed reactivity of IgG bands with recombinant HuD antigen in all CSF samples. These data support the idea that HuD specific antibodies in the CSF are produced mainly by B-cell clones in the central nervous system. These findings support the hypothesis of autoimmunity in the pathogenesis of anti-Hu associated paraneoplastic neurological syndromes.

An improved, ultrasensitive method for the detection of IgM oligoclonal bands in cerebrospinal fluid

A new, 10-fold more sensitive method, based on an improved immunofixation technique, has been devised to detect oligoclonal IgM bands in unconcentrated cerebrospinal fluid (CSF). Using agarose gel electrophoresis, 5 microliters of an unconcentrated sample containing oligoclonal bands was separated and blotted on to a polyvinyldifluoride membrane. To visualise the pattern, a peroxidase-labelled double-antibody technique was used. No prior concentration of CSF was needed and the process required only 5 h. The technique may prove very useful in diagnosing an early intrathecal immune response.

Intrathecal immune response in patients with neuroborreliosis: specificity of antibodies for neuronal proteins

Cerebrospinal fluid (CSF) and serum samples of 47 patients with serologically proven neuroborreliosis were examined by Western blotting for antibodies to a crude extract of human cortex (CNS) comprising a multitude (> 40) of protein bands. Intrathecal synthesis of total immunoglobulins was determined by the Reiber formula and of autoantibodies to CNS proteins by enzyme-linked immunoassay (ELISA) and by Western blotting. Employing ELISA, intrathecal synthesis of autoantibodies (IgG, IgM and/or IgA) was demonstrated in 40 of 47 patients with neuroborreliosis (85%), in 5 of 40 with multiple sclerosis (12%), and in 22 of 40 with viral meningoencephalitis (55%). Of 40, 35 and 15 patients with neuroborreliosis and an intrathecal synthesis of total IgG, IgM or IgA, 20 revealed an intrathecal production of IgG antibodies (50%), 24 of IgM antibodies (68%) and 6 of IgA autoantiodies (40%) in the CSF. The specificity of autoantibodies differed greatly between most patients. Of 24 different CNS proteins which elicited an immune response in various patients, identities could be determined only for the myelin basic protein (5 of 40) and for the three neurofilament proteins (NF-68, NF-150, NF-200) (13 of 40 patients). In this limited number of patients no significant correlation between individual clinical symptoms and certain autoantiodies could be detected. The higher frequency of intrathecally produced autoantibodies in patients with neuroborreliosis is assumed to result from mitogenic rather than specific activation of autoreactive B-cell clones by Borrelia burgdorferi. The pathogenic relevance of these autoantibodies remains to be determined.

Intrathecal immune response in neuroborreliosis: importance of cross-reactive antibodies

The intrathecal IgG response to Borrelia burgdorferi was evaluated in 35 patients with neuroborreliosis (NB). Samples were tested with and without preabsorption with Treponema phagedenis. Specific antibody concentrations in the CSF and serum were determined by ELISA. The antibody index (AIBb = QBb/QIgG) was calculated from the ratio between the CSF/serum quotients for specific antibodies (QBb) and total IgG (QIgG). Intrathecal synthesis of B. burgdorferi antibodies was demonstrated in 31 samples before and in 24 samples after preabsorption with T. phagedenis. The clonal distribution of intrathecally produced IgG antibodies was determined by isoelectric focusing combined with affinity blotting. B. burgdorferi-specific oligoclonal IgG bands occurring predominantly in the CSF were demonstrated in 32/35 patients. In 29/32 samples, the major proportion of these bands also reacted with T. phagedenis. Preabsorption of samples with T. phagedenis removed a considerable share of bands reacting with B. burgdorferi. In patients with neurosyphilis, intrathecal synthesis of antibodies with specificity for B. burgdorferi was demonstrated in 7/10 samples before, and in no sample, after preabsorption of cross-reactive antibodies. Due to the lower sensitivity in determining the AIBb (-20%), preabsorption of cross-reactive antibodies cannot be generally recommended. In all patients with suspected neuroborreliosis, but uncommon neurological symptoms and missing anamnestic data concerning a tick bite or erythema migrans, neurosyphilis should be excluded by a negative TPHA test.

Occurrence of oligoclonal IgM bands in the cerebrospinal fluid of neurological patients: an immunoaffinity-mediated capillary blot study

We developed a highly sensitive and specific immunoaffinity-mediated capillary blot technique for the detection of oligoclonal IgM bands in CSF and sera from patients with various neurological disorders. Pre-treatment of the samples by dithiothreitol was necessary to obtain a migration of the IgM molecule into the gel of isoelectric focusing. IgM was then transferred by immunoaffinity onto a polyvinylidene difluoride sheet previously coated with anti-IgM antiserum. The limit of detection was found to be 6 ng in 15-microliters samples. The presence of CSF-restricted IgM bands was considered the result of an intrathecal synthesis and was observed in 13 out of 46 (28%) patients with MS, more frequently in acute relapses (9 out of 21, 43%), including 6 cases out of 13 presenting the first bout of the disease. Similar IgM bands were also detected in 15 out of 46 (38%) patients with CNS infections, especially in cases of neurosyphilis and neuroborreliosis. The presence of CSF oligoclonal IgM bands was linked to an increase of the IgM index in the MS group, but not in the group of infectious diseases as a whole. The occurrence of CSF-restricted oligoclonal IgM bands seems to be the most specific indicator of an intrathecal synthesis of this isotype.

A high-sensitivity immuno-chemiluminescence technique for detection of oligoclonal IgG and IgM in unconcentrated cerebrospinal fluid

A method is described for detection of oligoclonal IgG and IgM in unconcentrated cerebrospinal fluid (CSF). The proteins were separated by agarose gel electrophoresis and transferred to cellulose nitrate membranes. A double antibody technique with a peroxidase conjugated secondary antibody was used to detect the protein. Bound secondary antibody was visualized by autoradiography using chemiluminescence (ECL) reagent. The procedure presented here allows examination of oligoclonal bands of IgG and IgM in less than 6h. The detection limit for a single band was approximately 10pg and the results were in complete agreement with those achieved by isoelectric focusing (Phast System) and subsequent immunofixation. In 9 of the samples oligoclonal IgM was also detected.

Polyclonal and oligoclonal IgA synthesis in the cerebrospinal fluid of neurological patients: an immunoaffinity-mediated capillary blot study

An intrathecal synthesis of IgA has been reported in various neurological disorders. However, the frequency of its occurrence and the electrophoretic characteristics of the locally produced IgA remained a matter of controversy. We developed a sensitive immunoaffinity-mediated capillary blot technique for the detection of polyclonal and oligoclonal IgA in the CSF of 115 patients with various neurological disorders. Paired CSF and serum samples containing 50 ng IgA after appropriate dilutions were submitted to isoelectric focusing in agarose gels; IgA was then blotted onto a polyvinylidene difluoride sheet coated by an anti-IgA antiserum or by infectious antigens. The immunoblots were revealed by an alkaline phosphatase-conjugated anti-IgA antiserum. Only five samples displayed CSF-restricted oligoclonal IgA bands, including two out of 33 from MS patients. In herpetic encephalitis (n = 5) and varicella-zoster meningitis (n = 2), a strong intrathecal production of virus-specific IgA antibodies was detectable. In such cases, faint oligoclonal IgA antibodies were superimposed on a polyclonal background. A weak local production of anti-Borrelia burgdorferi IgA antibodies was present in two out of four cases of neuroborreliosis.

Lack of both spinal fluid oligoclonal bands and complement 4A protein in an MS patient

We report the case of a multiple sclerosis (MS) patient without oligoclonal bands (OCB) in three cerebrospinal fluid samples. Restriction fragment length polymorphism analysis of Class 3 genes with radiolabelled specific cDNA probes showed a homozygous deletion of the complement 4A (C4A) genes. Consequent lack of C4A protein can alter the development of humoral immune response probably preventing OCB production. Our observation may suggest a link between a rare immunogenetic pattern and the absence of OCB in MS.

Guillain-Barré syndrome following streptokinase therapy

Clinical and laboratory data from a patient with Guillain-Barré syndrome indicated a probable etiological correlation of polyradiculitis to the intravenous administration of streptokinase. Oligoclonal IgG bands in the cerebrospinal fluid and serum were shown to be specific for streptokinase. Serum titers of streptokinase were elevated 64-fold for IgG, 16-fold for IgM, and 4-fold for IgA compared to controls. Clinical symptoms of Guillain-Barré syndrome are thought to result from streptokinase antibody complex mediated damage to the local blood-nerve barrier. The pathogenic relevance of autoantibodies to albumin and proteins of the central and peripheral nervous systems, occurring early after onset of symptoms, remains to be determined.

GFAP-specific oligoclonal bands in the CSF of a patient with acute myelitis

The specificity for GFAP (glial fibrillary acidic protein) of oligoclonal IgG bands in the CSF of a patient with acute myelitis was demonstrated by isoelectric focusing and affinity blotting. Findings were confirmed by western blotting using a monoclonal antibody to GFAP as a reference. Immune reactions to this astrocyte protein are considered as arising secondary to spinal cord tissue lesion.

Intrathecal synthesis of specific antibodies in neuroborreliosis. Comparison of different ELISA techniques and calculation methods

The sensitivity of six different ELISA techniques and calculation methods for the determination of intrathecal synthesis of IgG antibodies specific to Borrelia burgdorferi was investigated in paired CSF and serum specimens from 33 patients with neuroborreliosis. The diagnostic value of the Antibody Index (AI) was compared with the meaningfulness of serum antibodies to B. burgdorferi (Bb), established by immunofluorescence assay (IFA). The AI, as a standard for intrathecal antibody synthesis was determined from specific antibody ratios (QBb) in the CSF and serum and the CSF/serum ratio of IgG (QIgG) or albumin (QAlb). Using Western blotting with identical concentrations of IgG in the CSF and serum all patients displayed intrathecal synthesis of specific antibodies to at least two B. burgdorferi proteins. The different ELISA methods and calculation procedures were almost equivalent in demonstrating intrathecal synthesis of specific antibodies (32 and 33/33). Calculation of AI from IFA titers was somewhat less sensitive (30/33). In 5 patients titers of serum IgG- and IgM-antibodies to B. burgdorferi determined by IFA were within the normal range or borderline, while elevated AIBb values indicated an autochthonous immune response to B. burgdorferi in the CSF. In uncertain cases of neuroborreliosis calculation of AI from ELISA titers will be useful in clarifying the diagnosis.

Intrathecal synthesis of IgM and IgA in neurological diseases: comparison of two formulae with isoelectric focusing

The intrathecal IgM and IgA immune response was studied by detecting oligoclonal IgM and IgA bands in CSF and by determining both the IgM/IgA indices as well as the intrathecal production of IgM and IgA by the Reiber formula. A good correlation was found between the demonstration of oligoclonal IgM (r = 0.890) and IgA bands (r = 0.927) and the Reiber formula. Compared with the finding of oligoclonal IgM/IgA bands calculation of an intrathecal IgM/IgA synthesis by the Reiber formula was less sensitive (86%). In two out of 22 controls and in 12 of 19 patients with polyradiculitis IgM and IgA indices were elevated while the other evaluation methods were negative. Even though oligoclonal IgM and IgA bands are considered to be a useful diagnostic tool in detecting intrathecal synthesis of IgM and IgA, i.e. in meningoencephalitis or neuroborreliosis for clinical practice, the Reiber formula provides reliable results. Detection sensitivity of assays for CSF-IgM and -IgA should be at least 1.0 mg/l.

Intrathecal synthesis of anti-Borrelia burgdorferi antibodies in neuroborreliosis: a study with special emphasis on oligoclonal IgM antibody bands

Pre- and post-treatment (up to 3-26 months after antibiotic therapy) humoral immune responses were investigated in five neuroborreliosis patients. Anti-Borrelia (B.) burgdorferi IgG and IgM antibodies in CSF and serum were quantitated by capture ELISA. Agarose gel isoelectric focusing (AIF) and protein blotting were used to detect oligoclonal IgG and IgM bands as well as oligoclonal anti-B. burgdorferi IgG and IgM antibodies. These latter components were visualized by transfer to antigen-coated membranes (immunoblot) and immunoenzymatic staining. By ELISA, intrathecal anti-B. burgdorferi IgG and IgM antibody synthesis was detected in all initial specimens and continued 3-26 months after antibiotic therapy in four and three cases, respectively. AIF with protein blotting showed oligoclonal bands of total IgG as well as total IgM in the initial CSF specimens of all patients and persistence of such components occurred in four and five cases, respectively. By AIF and immunoblot, oligoclonal anti-B. burgdorferi IgG and IgM antibody bands could be detected in the CSF of every patient. IgG antibody bands were present in all initial CSF samples. The first specimen of one patient was negative for IgM antibody bands but such components appeared 3 weeks later. Oligoclonal CSF anti-B. burgdorferi IgG antibody components persisted over the entire follow-up periods in all but one case where they disappeared 6 weeks after treatment. The oligoclonal IgM antibodies in CSF vanished in two cases (after being present up to 4 and 11 months after antibiotic therapy) while they persisted over the entire (3-6 months after antibiotic therapy) follow-up periods in three cases. The specificity of the IgM antibody immunoblot technique was corroborated by control experiments, including antibody absorption studies and use of 41 kDa flagellar antigen.