The Subclass Nature and Clinical Significance of the IgG Antibody Response in Patients Undergoing Allergen-Specific Immunotherapy

The purpose of this paper is to discuss the methodological difficulties in quantitation of human IgG subclass antibodies to allergens, to describe the subclass nature of the IgG antibody response in patients undergoing allergen-specific immunotherapy, and to discuss the possible immunological functions and clinical significance of allergen-specific IgG antibodies of different subclasses. Based on results obtained by use of assays with documented specificity it is concluded that the IgG antibody response during allergen-specific immunotherapy is IgG1 and IgG4 restricted, although low levels of IgG2 and IgG3 antibodies to some allergens may occur. In most patients the early IgG antibody response is IgG1 dominated and the late IgG4 dominated. A too early or too pronounced IgG4 dominated antibody response seems to indicate a poor clinical outcome of immunotherapy with inhalant allergens, whereas a pronounced early IgG1 antibody production has been found to be associated with a decrease in synthesis of IgE antibodies to an insect venom. It is therefore proposed that an early IgG1 dominated response is necessary to induce suppression of the ongoing IgE antibody production, which in its turn may be a prerequisite for long-lasting clinical effect. The possibility of induction of an early IgG1 dominated response in every patient by use of alternative immunotherapy procedures is discussed.     

Demystifying Analytical Approaches for Urine Drug Testing to Evaluate Medication Adherence in Chronic Pain Management

ABSTRACT

This comprehensive review of analytical methods used for urine drug testing for the support of pain management describes the methods, their strengths and limitations, and types of analyses used in clinical laboratories today. Specific applications to analysis of opioid levels are addressed. Qualitative versus quantitative testing, immunoassays, chromatographic methods, and spectrometry are discussed. The importance of proper urine sample collection and processing is addressed. Analytical explanations for unexpected results are described. This article describes the scientific basis for urine drug testing providing information which will allow clinicians to differentiate between valid and questionable claims for urine drug testing to monitor medication adherence among chronic pain patients.     

The detection of influenza A and B viruses in clinical specimens using a quartz crystal microbalance

Detection of human immunodeficiency virus (HIV) infections has been enhanced by incorporating p24 antigen detection with current HIV antibody detection using enzyme immunoassays (EIAs). However, screening for HIV antibodies has increased through the use of rapid, lateral-flow HIV antibody detection assays that currently do not have the capability to detect HIV p24 antigen. In this report, a lateral-flow based assay using super-paramagnetic particles as the detection marker was developed for the detection of HIV-1 p24 antigen. This magnetic immuno-chromatographic test (MICT) uses an inexpensive, low-maintenance instrument that detects the magnetic moment of the super-paramagnetic particles in a magnetic field. MICT is simple to perform, provides a numerical output for easier determination of reactive results and can be completed in 40 min. The lower limit of detection for HIV-1 p24 spiked into assay sample buffer and 50% plasma was 30 pg/ml for both. Detection of HIV-1 p24 antigen at 50 pg/ml was reproducible in both inter-run and intra-run assays with coefficients of variation of <13%. Furthermore, the MICT p24 assay was able to detect intact virus spiked into 50% plasma (lower detection limit of 250,000 viral RNA copies/ml). MICT detection of increasing HIV-1 p24 levels in commercially available seroconversion panels by MICT was only slightly later than that detected by much more complex EIAs. MICT could provide a simple, low-cost, and portable method for rapid HIV-1 p24 detection in a variety of testing environments.     

The sera of patients with acquired immunodeficiency syndrome contain specific antibodies in a latent state

Latent antibodies reacting with antigens of human immunodeficiency virus are detected in patients with acquired immunodeficiency syndrome. Antibodies are detected by ion-exchange chromatography on QAE-Sephadex. A relationship is noted between the disease stage and the level of latent antibodies. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny Vol. 121, N ^o 3, pp. 315–316, March, 1996 Presented by A. F. Tsyb, Member of the Russian Academy of Medical Sciences     

血清抗体检测在一起本地传播新冠肺炎聚集性疫情溯源调查中的应用

目的 在深圳市一起本地传播COVID - 19聚集性疫情溯源调查中,对重点涉疫人群开展抗体检测,帮助明确疫情扩散范围,追踪可能的源头。方法 采用流行病学调查、大数据手段锁定重点涉疫人群,除对其开展SARS - COV - 2核酸检测外,采用化学发光法检测抗体,对阳性者进一步开展流行病学调查和中和抗体检测,判断其在疫情传播中的作用。结果 该疫情的9名个案在病程中均检测到IgM抗体、IgG抗体阳性。5 606名涉疫人员检测了抗体,26人阳性,初筛阳性率为0.47%,其中11人IgG抗体阳性,15人IgM抗体阳性;但中和抗体实验和核酸检测均阴性。3人曾经出现过呼吸道症状,均否认与深港货车司机、国外入境人员、冷冻进口货物和发热呼吸道病例接触史。某口岸附近小区阳性率高于其他场所,差异有统计学意义（χ2 = 8.29,P = 0.004）。结论 通过核酸和抗体检测结果可判断,本起疫情传播范围较为局限;化学发光抗体检测法有一定假阳性率,可以作为新冠肺炎疫情溯源调查的辅助方法,对有流行病学史的涉疫人员进行筛查,但不宜对一般人群进行大规模筛查。     

Heparin-induced thrombocytopenia: evaluation of IgG and IgGAM ELISA assays

Background: Heparin‐induced thrombocytopenia (HIT) is a rare complication of heparin therapy resulting from antibody production to platelet factor 4 and heparin complexes (H‐PF4). Methods: We have evaluated four enzyme‐linked immunosorbent assay (ELISA)‐based screening tests to identify the best assay(s) with the highest specificity but without underdiagnosis of HIT. As functional assays are difficult to perform, ELISAs are useful to provide clinicians with a timely answer. Over a 10‐month period, all samples (N = 107) referred to our laboratory were tested for HIT antibodies using four commercially available ELISA kits, two detecting IgG/A/M anti‐H‐PF4 antibodies and the other two IgG specific. Results: Twenty‐eight samples were positive by at least one assay; IgGAM ELISAs were found to be more sensitive with 24 samples positive by Asserachrom IgGAM and 23 by Zymutest IgGAM. Only 18 samples were positive by GTI‐PF4‐IgG and Zymutest IgG. The gold standard serotonin release assay (SRA) was used as a confirmation assay, and 11/28 samples tested positive. All these SRA‐positive samples were positive by all four assays. None of the IgGAM‐only‐positive samples was found to be positive by SRA suggesting a better specificity for the IgG‐only assays. Conclusion: Our data strongly support the use of IgG‐only assays for the detection of HIT antibodies.     

International study to compare antigen-specific methods used for the measurement of antiplatelet autoantibodies

Platelet-associated and plasma autoantibodies against platelet glycoproteins (GP) have been demonstrated in patients with autoimmune thrombocytopenia (AITP) using various methods. Eight laboratories in seven countries participated in this international study to evaluate the interlaboratory agreement using glycoprotein-specific immunoassays for these autoantibodies. The participating laboratories received blind samples of frozen washed platelets and plasma from 22 normal donors and 22 AITP patients. Platelet-associated and plasma autoantibodies against GPIIb–IIIa and GPIb–IX were measured by MAIPA, immunobead assay or modified antigen capture assay. Of the control samples, 96.0% and 97.2% of all results for platelet-associated and plasma autoantibodies to GPIIb–IIIa/GPIb–IX, respectively, were negative. The mean variation coefficient of the control samples of platelet-associated and plasma autoantibodies was 89.5% (range 11.1–272.9%) and 46.5% (range 21.0–78.0%), respectively. In 20/22 patient samples, platelet-associated autoantibodies to either glycoprotein were noted by at least two laboratories. The mean degree of agreement in these samples was 74.0%. There was a significant correlation in the individual antibody measurements between all laboratories (Kendall coefficient of concordance 0.60 and 0.38, P < 0.001; Spearman rank order test, range of correlation coefficient 52.3–94.0% and 42.2–85.0%, P < 0.05, for anti-GPIIb–IIIa and anti-GPIb–IX, respectively). In contrast, plasma autoantibodies to either glycoprotein were noted by at least two laboratories in only 13/22 patient samples. Moreover, the degree of agreement was poor (50.1%) and a significant correlation was noted between only six pairs of laboratories. We conclude that methods used in this study yield good interlaboratory agreement in measuring platelet-associated autoantibodies against GPIIb–IIIa and GPIb–IX. In contrast, poor agreement was found in detecting plasma autoantibodies to the same glycoproteins.     

Polymorphism in the C-reactive protein (CRP) gene affects CRP levels in plasma and one early marker of atherosclerosis in men: The Health 2000 Survey

The gastrointestinal hormone gastrin is measured in plasma in physiological, pathophysiological and diagnostic investigations. In the diagnosis of hypergastrinaemic diseases such as gastrinomas and gastric achlorhydria, measurement of gastrin concentrations in circulation is crucial. Gastrin circulates, however, not as a single peptide but as a mixture of peptides of different lengths and amino acid derivatizations. Moreover, in hypergastrinaemia the peptide pattern changes. Consequently, diagnostic gastrin measurements require immunoassays that recognize the pathological plasma patterns, which are characterized by a predominance of the large peptides (gastrin‐34 and gastrin‐71) and less, if any, of the shorter main form of gastrin in normal tissue, gastrin‐17. Alternatively, and in specific cases, “processing‐independent assays” (PIA) for progastrin may be considered, since hypersecreting gastrin cells also release substantial amounts of biosynthetic precursors and processing intermediates. Recently, gastrin kits that do not take the pathological plasma patterns into account have been marketed and may miss the diagnosis. Therefore, proper diagnosis of gastrinomas and other hypergastrinaemic diseases requires insight into cellular gastrin synthesis and peripheral metabolism, and also into the design of useful immunoassays. This review discusses the art of measuring gastrin in plasma with adequate diagnostic specificity.     

Diagnostic ability of different human milk fat globule antigens in breast cancer

Human mammary epithelial antigens (HME-Ags) are released into the circulation by breast tumors and not by normal breast tissue (Proc. Natl. Acad. Sci. USA 74: 582–586, 1977). This characteristic made them valuable, together with other breast cancer related antigens later identified, to develop immunoassays useful in the follow-up of breast cancer. Assays for these antigens in serum have less than complete sensitivity and partial specificity, and as a result of this have not been totally successful in studying the relapsing breast cancer patient. In the present work, correlations are made among 3 assays available for breast cancer disease follow-up. They detect HME-Ags, CEA, and the heavy molecular weight mucin of the human milk fat globule (HMFG). Values for sensitivity and specificity for the 3 assays were obtained from approximately 300 samples of patients whose clinical diagnosis at the time of blood drawing was rigorously established. A small but definite advantage in sensitivity is demonstrated for the HME-Ags assay over the other two. A similar advantage is also demonstrated in the sequential follow-up of breast cancer patients, where HME-Ags respond more rapidly in most instances to changes in tumor burden. Further, the ability of increases in levels of these assays to predict relapse was studied in 15 patients who relapsed. HME-Ags demonstrated a predictive value of 73%, while CEA and the heavy molecular weight mucin remained at 47%.The present study exemplifies the search for novel antigens (Ags) with maximal ability to detect breast cancer relapse and with improved sensitivity to monitor tumor burden changes. Here, assays for different antigens to be compared are tested in the same serum samples obtained from carefully staged patients. The results suggest a role as breast cancer markers for antigens of lower molecular weight than the epithelial mucin-like components studied previously.