Specific Cerebrospinal Fluid SerpinA1 Isoform Pattern in Alzheimer's Disease.

SerpinA1 (α1-antitrypsin) is a soluble glycoprotein, the cerebrospinal fluid (CSF) isoforms of which showed disease-specific changes in neurodegenerative disorders that are still unexplored in Alz-heimer's disease (AD). By means of capillary isoelectric focusing immunoassay, we investigated six serpinA1 isoforms in CSF samples of controls (n = 29), AD-MCI (n = 29), AD-dem (n = 26) and Lewy body disease (LBD, n = 59) patients and correlated the findings with CSF AD core biomarkers (Aß42/40 ratio, p-tau, t-tau). Four CSF serpinA1 isoforms were differently expressed in AD patients compared to controls and LBD patients, especially isoforms 2 and 4. AD-specific changes were found since the MCI stage and significantly correlated with decreased Aß42/40 (p < 0.05) and in-creased p-tau and t-tau levels in CSF (p < 0.001). Analysis of serpinA1 isoform provided good di-agnostic accuracy in discriminating AD patients versus controls (AUC = 0.80) and versus LBD patients (AUC = 0.92), with best results in patients in the dementia stage (AUC = 0.97). SerpinA1 isoform expression is altered in AD patients, suggesting a common, albeit disease-specific, in-volvement of serpinA1 in most neurodegenerative disorders.

CSF SerpinA1 in Creutzfeldt-Jakob disease and frontotemporal lobar degeneration.

OBJECTIVE: SerpinA1 (alpha-1 antitrypsin) is an acute inflammatory protein, which seems to play a role in neurodegeneration and neuroinflammation. In Alzheimer's disease and synucleinopathies, SerpinA1 is overexpressed in the brain and the cerebrospinal fluid (CSF) showing abnormal patterns of its charge isoforms. To date, no comprehensive studies explored SerpinA1 CSF isoforms in Creutzfeldt-Jakob disease (CJD) and frontotemporal lobar degeneration (FTLD). METHODS: Using a capillary isoelectric focusing immunoassay, we analyzed CSF SerpinA1 isoforms in control cases (n = 31) and patients with a definite or probable diagnosis of CJD (n=77) or FTLD (n = 30), belonging to several disease subtypes. RESULTS: The overall SerpinA1 signal was significantly higher than in controls in CJD subtypes linked to abnormal prion protein (PrPSc ) type 1, such as sporadic CJD (sCJD) MM(V)1, and in FTLD-TDP. Moreover, CJD linked to PrPSc type 1 and FTLD-TAU groups showed a significant relative increase of acidic and basic isoforms in comparison with controls, thereby forming two distinct SerpinA1 isoform profiles. INTERPRETATION: CJD linked to PrPSc type 1 and FTLD show a differential upregulation and post-translational modifications of CSF SerpinA1. Further studies are needed to clarify whether these findings may reflect a common, albeit disease-specific, pathogenetic mechanism related to neurodegeneration.

Do fragments and glycosylated isoforms of alpha-1-antitrypsin in CSF mirror spinal pathophysiological mechanisms in chronic peripheral neuropathic pain? An exploratory, discovery phase study.

BACKGROUND: Post-translational modifications (PTMs) generate a tremendous protein diversity from the ~ 20,000 protein-coding genes of the human genome. In chronic pain conditions, exposure to pathological processes in the central nervous system could lead to disease-specific PTMs detectable in the cerebrospinal fluid (CSF). In a previous hypothesis-generating study, we reported that seven out of 260 CSF proteins highly discriminated between neuropathic pain patients and healthy controls: one isoform of angiotensinogen (AG), two isoforms of alpha-1-antitrypsin (AT), three isoforms of haptoglobin (HG), and one isoform of pigment epithelium-derived factor (PEDF). The present study had three aims: (1) To examine the multivariate inter-correlations between all identified isoforms of these seven proteins; (2) Based on the results of the first aim, to characterize PTMs in a subset of interesting proteins; (3) To regress clinical pain data using the 260 proteins as predictors, thereby testing the hypothesis that the above-mentioned seven discriminating proteins and/or the characterized isoforms/fragments of aim (2) would be among the proteins having the highest predictive power for clinical pain data. METHODS: CSF samples from 11 neuropathic pain patients and 11 healthy controls were used for biochemical analysis of protein isoforms. PTM characterization was performed using enzymatic reaction assay and mass spectrometry. Multivariate data analysis (principal component analysis and orthogonal partial least square regression) was applied on the quantified protein isoforms. RESULTS: We identified 5 isoforms of AG, 18 isoforms of AT, 5 isoforms of HG, and 5 isoforms of PEDF. Fragments and glycosylated isoforms of AT were studied in depth. When regressing the pain intensity data of patients, three isoforms of AT, two isoforms of PEDF, and one isoform of angiotensinogen "reappeared" as major results, i.e., they were major findings both when comparing patients with healthy controls and when regressing pain intensity in patients. CONCLUSIONS: Altered levels of fragments and/or glycosylated isoforms of alpha-1-antitrypsin might mirror pathophysiological processes in the spinal cord of neuropathic pain patients. In particular, we suggest that a putative disease-specific combination of the levels of two different N-truncated fragments of alpha-1-antitrypsin might be interesting for future CSF and/or plasma biomarker investigations in chronic neuropathic pain.

Particle-based N-linked glycan analysis of selected proteins from biological samples using nonglycosylated binders.

Glycosylation is one of the most common and important post-translational modifications, influencing both the chemical and the biological properties of proteins. Studying the glycosylation of the entire protein population of a sample can be challenging because variations in the concentrations of certain proteins can enhance or obscure changes in glycosylation. Furthermore, alterations in the glycosylation pattern of individual proteins, exhibiting larger variability in disease states, have been suggested as biomarkers for different types of cancer, as well as inflammatory and neurodegenerative diseases. In this paper, we present a rapid and efficient method for glycosylation analysis of individual proteins focusing on changes in the degree of fucosylation or other alterations to the core structure of the glycans, such as the presence of bisecting N-acetylglucosamines and a modified degree of branching. Streptavidin-coated magnetic beads are used in combination with genetically engineered immunoaffinity binders, called VHH antibody fragments. A major advantage of the VHHs is that they are nonglycosylated; thus, enzymatic release of glycans from the targeted protein can be performed directly on the beads. After deglycosylation, the glycans are analyzed by MALDI-TOF-MS. The developed method was evaluated concerning its specificity, and thereafter implemented for studying the glycosylation pattern of two different proteins, alpha-1-antitrypsin and transferrin, in human serum and cerebrospinal fluid. To our knowledge, this is the first example of a protein array-type experiment that employs bead-based immunoaffinity purification in combination with mass spectrometry analysis for fast and efficient glycan analysis of individual proteins in biological fluid.

Reduced levels of alpha-1-antitrypsin in cerebrospinal fluid of amyotrophic lateral sclerosis patients: a novel approach for a potential treatment.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative motor neuron disease that involves activation of the immune system and inflammatory response in the nervous system. Reduced level of the immuno-modulatory and anti-inflammatory protein alpha-1-antitrypsin (AAT) is associated with inflammation-related pathologies. The objective of the present is to determine AAT levels and IL-23 in the cerebrospinal fluid (CSF) of ALS patients and control group. FINDINGS: CSF samples from newly diagnosed ALS patients and age-matched controls were analyzed for AAT and IL-23 by ELISA and magnetic luminex screening, respectively. A statistically significant reduction of 45 % in mean AAT levels was observed in the CSF of ALS patients (21.4 µg/ml) as compared to the control group (mean 38.8 µg/ml, p = 0.013). A statistically significant increase of 30.8 % in CSF mean levels of the pro-inflammatory cytokine IL-23 was observed in ALS patients (1647 pg/ml) in comparison to the controls (1259 pg/ml, p = 0.012). A negative correlation coefficient (r = -0.543) was obtained by linear regression analysis of the two measured parameters (p = 0.036). CONCLUSIONS: Reduced AAT and elevated IL-23 CSF levels support the notion of neuroinflammatory process occurring in ALS patients. Increasing AAT levels in the patients' nervous system should be further investigated as a new therapeutic approach and a novel potential tool for ALS treatment.

Modified serpinA1 as risk marker for Parkinson's disease dementia: Analysis of baseline data.

Early detection of dementia in Parkinson disease is a prerequisite for preventive therapeutic approaches. Modified serpinA1 in cerebrospinal fluid (CSF) was suggested as an early biomarker for differentiation between Parkinson patients with (PDD) or without dementia (PD). Within this study we aimed to further explore the diagnostic value of serpinA1. We applied a newly developed nanoscale method for the detection of serpinA1 based on automated capillary isoelectric focusing (CIEF). A clinical sample of 102 subjects including neurologically healthy controls (CON), PD and PDD patients was investigated. Seven serpinA1 isoforms of different charge were detected in CSF from all three diagnostic groups. The mean CSF signals of the most acidic serpinA1 isoform differed significantly (p < 0.01) between PDD (n = 29) and PD (n = 37) or CON (n = 36). Patients above the cut-off of 6.4 have a more than six times higher risk for an association with dementia compared to patients below the cut off. We propose this serpinA1 CIEF-immunoassay as a novel tool in predicting cognitive impairment in PD patients and therefore for patient stratification in therapeutic trials.

Differential sialylation of serpin A1 in the early diagnosis of Parkinson's disease dementia.

The prevalence of Parkinson's disease (PD) increases with age. Up to 50% of PD show cognitive decline in terms of a mild cognitive impairment already in early stages that predict the development of dementia, which can occur in up to 80% of PD patients over the long term, called Parkinson's disease dementia (PDD). So far, diagnosis of PD/PDD is made according to clinical and neuropsychological examinations while laboratory data is only used for exclusion of other diseases. The aim of this study was the identification of possible biomarkers in cerebrospinal fluid (CSF) of PD, PDD and controls (CON) which predict the development of dementia in PD. For this, a proteomic approach optimized for CSF was performed using 18 clinically well characterized patients in a first step with subsequent validation using 84 patients. Here, we detected differentially sialylated isoforms of Serpin A1 as marker for differentiation of PD versus PDD in CSF. Performing 2D-immunoblots, all PDD patients could be identified correctly (sensitivity 100%). Ten out of 24 PD patients showed Serpin A1 isoforms in a similar pattern like PDD, indicating a specificity of 58% for the test-procedure. In control samples, no additional isoform was detected. On the basis of these results, we conclude that differentially sialylated products of Serpin A1 are an interesting biomarker to indicate the development of a dementia during the course of PD.

Reduced levels of amyloid-beta-binding proteins in cerebrospinal fluid from Alzheimer's disease patients.

Amyloid-beta(Abeta) aggregation is a major hallmark of Alzheimer's disease (AD). Previous studies have suggested that only unbound Abeta can take part in the aggregation process. Therefore, endogenous Abeta-binding proteins may have an important role in preventing AD. Here, we analyzed cerebrospinal fluid (CSF) samples from 35 subjects with AD, 18 subjects with frontotemporal dementia (FTD) and 29 non-demented controls to test if reduced Abeta-binding capacity in CSF is a specific feature of AD. A panel of known Abeta-binding CSF proteins, including beta-trace/prostaglandin D2 synthase (beta-trace), transthyretin (TTR), cystatin C (CysC) and alpha(1)-antitrypsin (AAT), were quantified and related to diagnosis and CSF levels of Abeta(1-38), Abeta(1-40) and Abeta(1-42). AD patients displayed a mild reduction in the CSF levels of beta-trace (p=0.020), CysC (p=0.017), AAT (p=0.019) and TTR (p=0.012) compared with controls. While the reductions in AAT and TTR were AD-specific, the levels of beta-trace and CysC were also reduced in FTD. As expected, CSF Abeta(1-42) was reduced in AD compared with controls (p=0.00005) and with FTD patients (p=0.015). Positive correlations between Abeta(1-42) and beta-trace, CysC and TTR, respectively, were seen only in the AD group, suggesting that deficient Abeta-binding capacity in CSF may contribute to the amyloidogenic process in AD.

Comparative proteomics analysis of cerebrospinal fluid of patients with Guillain-Barré syndrome.

To better understand the pathophysiologic mechanisms underlying Guillain-Barré syndrome (GBS), Comparative proteomic analysis of cerebrospinal fluid (CSF) between patients with GBS (the experiment group) and control subjects suffering from other neurological disorders (the control group) was carried out using two-dimensional gel electrophoresis (2-DE) technique, in combination with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and database searching to determine abnormal CSF proteins in GBS patients. Image analysis of 2-DE gels silver stained revealed that 10 protein spots showed significant differential expression between the two groups of CSF samples. The expression of cystatin C, transthyretin, apolipoprotein E and heat shock protein 70 were decreased. However, haptoglobin, alpha-1-antitrypsin, apolipoprotein A-IV and neurofilaments were elevated. The subsequent ELISA measured the concentration of cystatin C and confirmed the result of the proteomic analysis. These identified proteins may be involved in the pathophysiological process of GBS and call for further studying the role of these proteins in the pathogenesis of the disease.

Plasma and CSF serpins in Alzheimer disease and dementia with Lewy bodies.

OBJECTIVE: Serine protease inhibitors (serpins), the acute phase reactants and regulators of the proteolytic processing of proteins, have been recognized as potential contributors to the pathogenesis of Alzheimer disease (AD). We measured plasma and CSF levels of serpins in controls and patients with dementia. METHODS: Using rocket immunoelectrophoresis, ELISA, and Luminex xMAP technology, we analyzed plasma levels of alpha(1)-antichymotrypsin and alpha(1)-antitrypsin, and CSF levels of alpha(1)-antichymotrypsin, alpha(1)-antitrypsin, and neuroserpin along with three standard biomarkers (total tau, tau phosphorylated at threonine-181, and the A beta(1-42)) in patients with AD (n = 258), patients with dementia with Lewy bodies (DLB; n = 38), and age-matched controls (n = 37). RESULTS: The level of CSF neuroserpin was significantly higher in AD compared with controls and DLB, whereas CSF alpha(1)-antichymotrypsin and alpha(1)-antitrypsin were significantly higher in both AD and DLB groups than in controls. Results from logistic regression analyses demonstrate a relationship between higher CSF levels of alpha(1)-antichymotrypsin and neuroserpin and increased predicted probability and odds ratios (ORs) of AD (OR 5.3, 95% CI 1.3 to 20.8 and OR 3.3, CI 1.3 to 8.8). Furthermore, a logistic regression model based on CSF alpha(1)-antichymotrypsin, neuroserpin, and A beta(1-42) enabled us to discriminate between AD patients and controls with a sensitivity of 94.7% and a specificity of 77.8%. CONCLUSIONS: Higher CSF levels of neuroserpin and alpha(1)-antichymotrypsin were associated with the clinical diagnosis of Alzheimer disease (AD) and facilitated the diagnostic classification of AD vs controls. CSF serpin levels did not improve the diagnostic classification of AD vs dementia with Lewy bodies.

Changes in concanavalin A-reactive proteins in neurological disorders.

Changes of glycosylation of cerebrospinal fluid proteins such as alpha2-macroglobulin, and prostaglandin D synthase were studied by lectin blotting, using concanavalinA, in multiple sclerosis (n = 42) and neuropathies (n = 20) in comparison to neurological controls (n = 22). The concanavalinA-reactivity of alpha2-macroglobulin, which was increased in the neuropathies but not in multiple sclerosis compared to controls, correlated with the total concanavalinA-reactivity in controls and neuropathies but not in multiple sclerosis, indicating that the protein could be abnormally glycosylated in the latter disease. Although the concentration and the concanavalinA-reactivity of prostaglandin D synthase were not significantly different in the three groups, the two parameters correlated only in neuropathies but not in controls or multiple sclerosis, probably due to the high heterogeneity of the protein. These changes deserve to be studied in further detail in view of their potential clinical applications.

[Usefulness of establishing chosen acute phase proteins concentrations in serum and cerebrospinal fluid for differential diagnosis and monitoring of purulent meningitis in adults. I]. / Przydatnosc oznaczania stezen wybranych bialek ostrej fazy w surowicy krwi i plynie mózgowo-rdzeniowym do diagnostyki róznicowej i monitorowania przebiegu ropnych zapalen opon mózgowo-rdzeniowych u doroslych. I. Stezenie bialek ostrej fazy w surowicy krwi.

40 adult patients were examined: 24 with purulent meningitis and 16 with lymphocytic meningitis. The control group consisted of 100 healthy people. In purulent meningitis patients in the 1st, 3rd, 5th, 7th, 14th and 28th day of the disease, concentrations of the following acute phase proteins were measured in serum: C-reactive protein, alpha 1-antitripsin, alpha 1-orosomucoid, alpha 2-ceruloplasmin, alpha 2-macroglobulin and alpha 2-haptoglobin. In lymphocytic meningitis patients concentrations of the above mentioned acute phase proteins were measured only in the 1st day of the disease. Usefulness of establishing alpha 2-haptoglobin, alpha 1-antitripsin, alpha 2-ceruloplasmin and particularly C-reactive protein concentrations for differential diagnosis of purulent and lymphatic meningitis was proved. Evaluation of C-reactive protein and alpha 1-antitripsin concentration kinetics proved to be fully useful for monitoring of seriousness of the course of purulent meningitis, and together with evaluation of the clinical condition of the patient it can constitute a valuable marker of effectiveness of the disease treatment.

[Usefulness of establishing chosen acute phase proteins concentrations in serum and cerebrospinal fluid for differential diagnosis and monitoring of purulent meningitis in adults. II]. / Przydatnosc oznaczania stezen wybranych bialek ostrej fazy w surowicy krwi i plynie mózgowo-rdzeniowym do diagnostyki róznicowej i monitorowania przebiegu ropnych zapalen opon mózgowo-rdzeniowych u doroslych. II. Stezenie bialek ostrej fazy w plynie mózgowo-rdzeniowym.

40 adult patients were examined: 24 with purulent meningitis and 16 with lymphocytic meningitis. In the course of purulent meningitis concentrations of the following acute phase proteins were measured in the cerebrospinal fluid: C-reactive protein, alpha 1-antitripsin, alpha 1-orosomucoid, alpha 2-ceruloplasmin, alpha 2-macroglobulin and alpha 2-haptoglobin in the 1st, 3rd, 5th, 7th, 14th and 28th day of the disease. In lymphocytic meningitis patients concentrations of the above mentioned acute phase proteins were measured only in the 1st day of the disease. Full usefulness of establishing concentrations of all the above mentioned acute phase proteins within the first five days of the purulent meningitis for differential diagnosis of purulent and lymphatic meningitis was proved. Evaluation of concentration kinetics of acute phase proteins in cerebrospinal fluid for monitoring of the course of purulent meningitis is of a limited value.

Aging and Alzheimer's disease: protease inhibitors in cerebrospinal fluid.

Recent advances suggested that proteases and their inhibitors could be implicated in the genesis and/or maturation of insoluble deposits associated with Alzheimer's disease (AD). This study was designed to measure the level of alpha 1-antichymotrypsin (ACT) and alpha 1-antitrypsin (AT) in cerebrospinal fluid (CSF) of patients with AD and nondemented humans at various ages. Our analysis failed to demonstrate a significant relationship between inhibitor content and disease. However, a positive correlation was observed between age and the ACT level for the normal control group. Such observation suggests a specific association of ACT with the mechanisms of brain aging.

Proteinase-antiproteinase imbalance in meningitis: determination of alpha 1 proteinase inhibitor (alpha 1PI), elastase-alpha 1PI complex, and elastase inhibition capacity in cerebrospinal fluid.

Mortality and long-term neurologic sequelae are still frequent complications of meningitis despite effective antibiotic treatment. This suggests that pathogen-independent inflammatory mechanisms may play an important role in the course of this illness. Neutrophil granulocytes form the primary immune defense in meningitis. Once activated, these cells release elastase into the cerebrospinal fluid (CSF). Elastase may induce tissue damage if local antiproteinase capacity is low as under normal conditions. To define the relevance of this mechanism we studied 22 patients with meningitis. Concentrations of elastase in complex with the main antiproteinase alpha 1-proteinase inhibitor (elastase-alpha 1 PI), alpha 1-proteinase inhibitor (alpha 1PI), and elastase inhibition capacity (EIC) were measured in CSF of 9 patients with bacterial meningitis (BM), aged 1 month-14 years; 13 patients with non-bacterial meningitis (NBM), aged 1 month-15 years; and 20 patients in whom meningitis was excluded after spinal tap (control group), aged 6 months-15 years. The concentration of elastase-alpha 1PI in the BM group (median 552 micrograms/l) was significantly higher than in either the NBM group (median 30 micrograms/l, p less than 0.01) or the control group (median 30 micrograms/l, p less than 0.01). Similarly, the alpha 1PI-concentration in the BM group was significantly higher (median 113 mg/l) than either the NBM group (median 13.7 mg/l, p less than 0.025) or the control group (median 6.3 mg/l, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[The value of granulocyte elastase in the early diagnosis of infantile meningitis]. / Utilidad de la elastasa granulocitaria en el diagnóstico precoz de las meningitis infantiles.

Elastase-alpha 1-proteinase inhibitor complex (E-alpha 1-PI) was evaluated in blood and cerebrospinal fluid in 176 patients between 1 month and 15 years old. They were divided in three groups: group 1 (n = 61) children without meningitis, group 2 (n = 69) non bacterial meningitis and group 3 (n = 46) bacterial meningitis. The CSF values of E-a 1-PI complex (P50: P2.5; P97.5) (micrograms/L) were (2.85: 0.1; 19.1) in group 1 (31.5: 0.88; 735) in group 2 and (247: 2.6; 10370) in group 3. Significant differences were found in it (p less than 0.001). We didn't find any differences between non bacterial meningitis group and bacterial meningitis group when the granulocytes count were below 100 X mm3. The blood values of E-a 1-PI complex (P50: P2.5; P97.5) (micrograms/L) were (1122: 337; 5005) in group 3, significantly greater (p less than 0.001) than in group 2 (346: 136; 1612). In CSF E-alpha 1-PI complex showed us a sensitivity of 89% and a specificity of 27.7% in the diagnosis of bacterial meningitis, while in blood stream, it was 85.3% and 85.4 respectively.

Cerebrospinal fluid alpha-1-antitrypsin alpha-1-antitrypsin-elastase complex levels in meningitis.

Alpha-1-antitrypsin (A-1-AT) and A-1-AT-elastase complex levels in cerebrospinal fluid have been evaluated in 11 children with viral meningitis (VM), 14 with bacterial meningitis (BM), 10 with tuberculous meningitis (TBM) and 10 investigated for, but found not to have meningitis (NM). A-1-AT concentrations in the NM group were lower than in the BM group (P = 0.0002) and the TBM group (P = 0.0005) but did not differ from the concentrations in VM; those in the VM group were lower than in the BM group (P = 0.0001) and the TBM group (P = 0.003) but no difference was found between the BM and TBM groups. A-1-AT-elastase complex concentrations in CSF were lower in the NM group than the BM group (P = 0.0001) or the TBM group (P = 0.0089), however those in the BM group were significantly higher than in the TBM group (P = 0.0001). A significant correlation existed in CSF between the protein concentrations and neutrophil counts as well as the A-1-AT and A-1-AT-elastase complex concentrations.

Lactoferrin, C-reactive protein, alpha-1-antitrypsin and immunoglobulin GA in cerebrospinal fluid in meningitis.

Cerebrospinal fluid measurements of lactoferrin and alpha-1-antitrypsin showed significant elevation in bacterial meningitis in children. 8 of 10 lactoferrin values and 6 of 11 alpha-1-antitrypsin values were above the upper range of controls. Both proteins correlated well with the total number of leukocytes in the cerebrospinal fluid. C-reactive protein, measured by either agglutination or radial immunodiffusion in the cerebrospinal fluid, failed to demonstrate any usefulness in diagnosing bacterial meningitis. Neither elevated serum C-reactive protein in cases of bacterial meningitis, nor sepsis, gave detectable concentrations of C-reactive protein in the cerebrospinal fluid.

Alpha 1-antitrypsin in cerebrospinal fluid of patients with neurologic diseases.

Proteases and their inhibitors have been implicated in the pathogenesis of neuroimmunologic diseases, particularly multiple sclerosis (MS). We measured the immunochemical level and functional activity of alpha 1-antitrypsin (AAT) in cerebrospinal fluid (CSF) and serum in patients with MS and other neurologic diseases. Increases in the immunochemical level of AAT in CSF correlated directly with disturbances in the blood-brain barrier, as reflected by the ratio of albumin in CSF to that in serum. The AAT activity in CSF directly correlated with the immunochemical level when all patients were compared. However, the AAT activity in patients with inflammatory diseases tended to be decreased relative to the immunochemical level, suggesting inactivation of AAT in these disorders. The AAT activity was not significantly altered in patients with MS, despite reports of increased protease activity in active MS.