The Missing Antibody: The pit-falls of ANCA testing Digby, James Wingfield, MBChB MRCP DTMH; Tinwell, Brendan, MBBCh FRCPath; Sheldon, Joanna, PhD FRCPath ...
The American journal of medicine,
2016
Journal Article
There are a number of pathological conditions in which tissue damage occurs in association with immune activation directed against components of normal tissue. The initial damaging events usually ...involve cells of the immune system, the T-cells, but the cell damage releases antigens that become targets for an antibody response. The detection and quantification of autoantibodies has become an important component in the diagnosis and management of autoimmune rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus, the systemic vasculitides and systemic sclerosis.
Each of these diseases is associated with a particular autoantibody or group of autoantibodies. They are usually detected by their reaction against tissue components using subjective methods such as indirect immunofluorescence. Any positive samples are further analysed using more specific and quantitative methods for the ‘quantification’ of the specific autoantibody concentration.
It is important that these autoantibodies are not considered to be ‘gold standard’ tests: they are no more than markers of the disease with significant limitations. They are best used as part of a diagnostic panel rather than as a marker indicating one particular disease. Techniques are gradually improving, giving numerical results rather than titres, but a lack of standardization makes these results extremely variable. Many of the markers show no correlation with disease activity. Their use should be restricted to the initial investigation and not repeated every time the patient is followed up. Other markers do, however, correlate with disease activity and can be used to monitor disease.
When investigating patients who have symptoms associated with autoimmune rheumatic diseases, analytes such as immunoglobulins, complement components and C-reactive protein may all be measured.
Non-typable
Haemophilus influenzae (NTHi) is an important human-specific respiratory pathogen colonizing the mucosa of the upper respiratory tract. The bacterium is a common cause of acute otitis ...media in children and exacerbations in patients with chronic obstructive pulmonary disease (COPD). An immunoglobulin (Ig) D-λ myeloma protein was found to detect a 16
kDa surface protein that we designated protein E (PE). The
pe gene was cloned using an NTHi genomic DNA library, and a truncated PE-derived protein lacking the endogenous signal peptide (PE22-160) was synthesized and produced in large amounts in
Escherichia coli. Interestingly, PE was expressed at the bacterial surface of NTHi as revealed by flow cytometry using the IgD-λ myeloma protein or PE-specific polyclonal antibodies. A PE-deficient NTHi mutant was produced and lost 50% of its adhesive capacity as compared to the wild-type counterpart when analysed for adhesion to type II lung alveolar epithelial cells. In parallel,
E.
coli expressing full-length PE1-160 adhered significantly more efficiently to epithelial cells as compared to wild-type
E.
coli. Recombinant IgD that recognized the chemical dansyl-chloride did not interact with PE indicating that the IgD-λ myeloma protein most likely was an antibody directed against the
H. influenzae surface epitope. In conclusion, we have discovered a novel NTHi outer membrane protein with adhesive properties using an IgD-myeloma protein.
In animal models, immunity to cryptococcal infection, as in many chronic fungal and bacterial infections, is associated with a granulomatous inflammatory response, intact cell-mediated immunity, and ...a Th1 pattern of cytokine release. To examine the correlates of human immunity to cryptococcal infection in vivo, we analyzed immune parameters at the site of infection over time and assessed the rate of clearance of infection by serial quantitative cerebrospinal fluid (CSF) fungal cultures in 62 patients in a trial of antifungal therapy for HIV-associated cryptococcal meningitis. CSF IL-6, IFN-gamma, TNF-alpha, and IL-8 were significantly higher in survivors compared with nonsurvivors. There were negative correlations between log TNF-alpha, IFN-gamma, and IL-6 levels and baseline cryptococcal CFU. Log IFN-gamma, G-CSF, TNF-alpha, and IL-6 were correlated positively with the rate of fall in log CFU/ml CSF/day. In a linear regression model including antifungal treatment group, baseline CFU, and these cytokines, only treatment group and log IFN-gamma remained independently associated with rate of clearance of infection. The results provide direct in vivo evidence for the importance of quantitative differences in IFN-gamma secretion in human immune control of granulomatous infections, and increase the rationale for adjunctive IFN-gamma in the treatment of refractory HIV-associated cryptococcosis.
Proinflammatory cytokines play a role in acute coronary events. However, the potential role of antiinflammatory cytokines in the modulation of the atherosclerotic process remains unknown. Interleukin ...(IL)-10, which is expressed in human atherosclerotic plaques, has potent deactivating properties in macrophages and T cells. The aim of this study was to assess whether serum concentrations of IL-10 differed between patients with unstable and stable angina pectoris.
A total of 95 patients with angina pectoris and angiographically documented coronary artery disease were studied. Of these, 50 patients had chronic stable angina (with stable symptoms over 3 months), and 45 patients had Braunwald class IIIB unstable angina with ST-segment changes. Serum IL-10 and IL-6 concentrations were measured on admission using commercially available immunoassays. Serum IL-10 concentrations were lower in unstable angina patients compared with those who had chronic stable angina (28.4 versus 14.0 pg/mL; 95% CI, 9.8 to 19.0; P<0.0001), even after adjustment for variables that were significantly different on univariate analysis. IL-6 concentrations were higher in the unstable angina group (20.9 versus 11.4 pg/mL; 95% CI, 1.0 to 12.6; P=0.04).
Patients with unstable angina had significantly lower serum IL-10 concentrations than did patients with chronic stable angina. This important finding is in keeping with previous data from animal model studies that suggest that IL-10 has a protective role in atherosclerosis.
Abstract
Background: Glioblastoma, the most common primary brain tumor, has variable prognosis. We aimed to identify serum biomarkers that predict survival of patients with glioblastoma.
Methods: In ...phase 1 (biomarker discovery), SELDI-TOF mass spectra were studied in 200 serum samples from 58 control subjects and 36 patients with grade II astrocytoma, 15 with anaplastic astrocytoma, and 91 with glioblastoma. To identify potential biomarkers, we searched for peptide peaks that changed progressively in size with increasing malignancy. One peak, identified as the B-chain of α2-Heremans-Schmid glycoprotein (AHSG), was less prominent with increasing tumor grade. We therefore investigated AHSG as a survival predictor in glioblastoma. We measured serum AHSG by turbidimetry and determined indices of malignancy, including tumor proliferation (Ki67 immunolabel) and necrosis (tumor lipids on magnetic resonance spectroscopy). In phase 2 (biomarker validation), the prognostic power of AHSG was validated in an independent group of 72 glioblastoma patients.
Results: Median survival was longer (51 vs 29 weeks) in glioblastoma patients with normal vs low serum AHSG concentrations (hazard ratio 2.7, 95% CI 1.5–5.0, P <0.001), independent of age and Karnofsky score. Serum AHSG inversely correlated with Ki-67 immunolabeling and tumor lipids. A prognostic index combining serum AHSG with patient age and Karnofsky score separated glioblastoma patients with short (<3 months) and long (>2 years) median survival. The prognostic value of serum AHSG was validated in a different cohort of glioblastoma patients.
Conclusions: We conclude that serum AHSG concentration, measured before starting treatment, predicts survival in patients with glioblastoma.
The balance between trophoblast cathepsin and decidual cystatin C expression is pivotal in physiological trophoblast development. Defective trophoblast invasion is characteristic of preeclampsia and ...may involve derangement of the cathepsin/cystatin C balance. We conducted a prospective nested case-control study of healthy women with singleton pregnancies in the first trimester of pregnancy. Maternal serum cystatin C concentrations in those subsequently developing preeclampsia (n = 30) were compared to controls with normal outcome (n = 90). The median cystatin C concentration in early pregnancy was significantly higher (P = .0001) in those who subsequently developed preeclampsia (median 0.65 mg/L) when compared to normal pregnancy (median 0.57 mg/L). Of the 30 women developing preeclampsia, 14 (47%) had cystatin C above the 80th centile (0.67 mg/L) for the controls. Maternal serum cystatin C concentrations in early pregnancy may be of value in identifying women at high risk of developing preeclampsia.
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