David J. Warren

Heterophilic antibody interference in immunometric assays

Immunometric assays are inherently vulnerable to interference from heterophilic antibodies, endogenous antibodies that bind assay antibodies. The consequences of such interference can be devastating. In this review, we discuss strategies that reduce the damage caused by heterophilic antibodies. Clinicians should only order blood tests that are indicated for the patient and clinical setting at hand, and have the confidence to question laboratory results discordant with the clinical picture. Laboratorians should familiarize themselves with the vulnerability of the assays they offer, and be able to perform and interpret adequate confirmatory measures correctly. When designing immunoassays, the immunoassay industry should invest the necessary resources in specific protective measures against heterophilic antibody interference. Examples include using antibody fragments and the addition of effective blockers to assay reagents. The increasing use of modified monoclonal mouse antibodies both in therapy and diagnostics could present a particular challenge in the future.

Switching from Remicade® to Remsima® is well Tolerated and Feasible: A Prospective, Open-label Study

Background and Aims A biosimilar version of infliximab [CT-P13/Remsima®] recently entered the European market. The clinical data on its use in inflammatory bowel disease [IBD] are sparse, especially on switching from the originator Remicade®. In this study, we aimed to prospectively investigate the feasibility, safety and immunogenicity of switching from Remicade to Remsima in a real-life IBD population. Methods All adult patients who were treated with Remicade in the Department of Gastroenterology at Oslo University Hospital were switched to Remsima. The follow-up lasted for 6 months. In addition, a retrospective registration was performed with a start time of 6 months before switching drugs. The primary endpoints were [i] the proportion of patients remaining on medication 6 months after switching and [ii] adverse events during the 6 months after switching. The secondary endpoints included [i] disease activity scores [Harvey-Bradshaw Index and Partial Mayo Score], C-reactive protein, haemoglobin, faecal calprotectin, infliximab dose and interval, and p-infliximab and [ii] the development of antidrug antibodies. Results In total, 143 IBD patients were switched, 99 with Crohns disease and 44 with ulcerative colitis. The large majority [97%] remained on the medication throughout follow-up. A low number of adverse events were observed. No change in disease activity, C-reactive protein, haemoglobin, faecal calprotectin, infliximab dose and interval or p-infliximab was detected. Three patients developed new detectable antidrug antibodies. Conclusions Switching from Remicade to Remsima was feasible and with few adverse events, including very limited antidrug antibody formation and loss of response.

Preparation of highly efficient electrocompetent Escherichia coli using glycerol/mannitol density step centrifugation

Traditional protocols for preparing Escherichia coli for electroporation are laborious and often deliver highly variable transformation efficiencies. Many laboratories resort to purchasing expensive commercially prepared cells. This article describes a simple method for producing electrocompetent E. coli by centrifuging bacteria through a glycerol/mannitol density cushion. The method is rapid and replaces tedious multistep procedures with two 15-min centrifugations. Standard cloning strains consistently produce more than 8×10(9)transformants/μg pUC18, whereas the strains TG1 and LE392 display efficiencies of more than 3×10(10)/μg DNA.

The new molecular markers DDIT3, STT3A, ARG2 and FAM129A are not useful in diagnosing thyroid follicular tumors

Preoperative characterization of thyroid follicular lesions is challenging. Fine-needle aspiration specimens cannot differentiate follicular carcinomas from benign follicular neoplasias. Recently, promising markers have been detected using modern molecular techniques. We conducted a retrospective study to confirm the usefulness of immunohistochemical staining for the protein markers, DDIT3, STT3A (ITM1), ARG2 and FAM129A (C1orf24) in separating benign and malignant thyroid follicular lesions. Formalin-fixed, paraffin-embedded thyroid tissue from 30 in-house cases (15 follicular carcinomas and 15 follicular adenomas), as well as 8 follicular carcinomas and 21 follicular adenomas on tissue microarray slides were stained immunohistochemically for DDIT3, STT3A, ARG2 and FAM129A expression. Control tissue consisted of thyroid parenchyma adjacent to the tumors and 11 separate cases of normal thyroid parenchyma. All in-house cases of follicular adenomas, follicular carcinomas and adjacent normal thyroid tissue showed positive immunostaining with anti-DDIT3 and anti-STT3A. Anti-ARG2 and anti-FAM129A polyclonal antibodies showed positive staining in 20 and 60% of in-house follicular adenomas, and 40 and 87% of in-house follicular carcinomas, respectively. Monoclonal anti-FAM129A demonstrated positive staining in 13 and 33% of in-house follicular adenomas and follicular carcinomas, respectively. Polyclonal anti-DDIT3, -STT3A and -FAM129A antibodies showed positive staining in all tissue microarray slides of follicular carcinoma and in 76, 85 and 81% of the follicular adenomas, respectively. Monoclonal anti-STT3A stained 81% of the follicular adenoma cores. Anti-ARG2 stained positive in 13% of follicular carcinomas and 10% of follicular adenomas on the tissue microarray slides. In conclusion, DDIT3, STT3A, ARG2 and FAM129A immunohistochemistry does not appear to be useful in the diagnosis of thyroid follicular neoplasias, as they do not reliably distinguish follicular thyroid carcinoma from follicular thyroid adenoma.

Separation principles of cycling temperature capillary electrophoresis

High throughput means to detect and quantify low‐frequency mutations (<10−2) in the DNA‐coding sequences of human tissues and pathological lesions are required to discover the kinds, numbers, and rates of genetic mutations that (i) confer inherited risk for disease or (ii) arise in somatic tissues as events required for clonal diseases such as cancers and atherosclerotic plaque.While throughput of linear DNAsequencing methods has increased dramatically, such methods are limited by high error rates (>10−3) rendering them unsuitable for the detection of low‐frequency risk‐conferring mutations among the many neutral mutations carried in the general population or formed in tissue growth and development. In contrast, constant denaturing capillary electrophoresis (CDCE), coupled with high‐fidelity PCR, achieved a point mutation detection limit of <10−5 in exon‐sized sequences from human tissue or pooled blood samples. However, increasing CDCEthroughput proved difficult due to the need for precise temperature control and the time‐consuming optimization steps for each DNAsequence probed. Both of these problems have been solved by the method of cycling temperature capillary electrophoresis (CTCE). The data presented here provide a deeper understanding of the separation principles involved in CTCEand address several elements of a previously presented two‐state transport model.

Studies on multiple forms of proGRP in serum from small cell lung cancer patients.

To determine whether various forms of progastrin-releasing peptide (proGRP) exist in the human circulation, a panel of monoclonal antibodies was produced to construct immunometric assays for various proGRP fragments. In combination with liquid chromatography, this facilitated the determination of fragment size distribution in the sera of patients with small cell lung cancer (SCLC). Separation of proGRP peptides from SCLC cell lines and patient samples by ion exchange and gel filtration resulted in the identification of several C-terminal fragments with wide differences in the relative amounts of each cleavage product. The high specificity of our immunometric assays for the various serum proGRP fragments indicates that they are promising tools for future investigations on the relationship between fragment distribution and diagnosis and prognosis.

A Man with Abdominal Pain: Enough Evidence for Surgery?

A 53-year-old man experienced periodic abdominal discomfort and a decreased capacity to work. His primary physician ordered a broad range of laboratory tests as part of the initial workup. The results revealed a greatly increased adrenocorticotropic hormone (ACTH)7 concentration of >1250 pg/mL (>278 pmol/L) [reference interval <46 pg/mL (<10.2 pmol/L)]. Cortisol was within the reference interval. Repeat measurements 4 weeks later confirmed the increased ACTH. Investigators rapidly excluded 2 well-known conditions associated with increased ACTH concentrations: Cushing disease (ACTH-producing pituitary tumor) and Addison disease (adrenal insufficiency) (1, 2). An investigation for an ectopic source of ACTH was begun (3). Over the next 18 months, the patient underwent a plethora of imaging studies. A series of conventional studies failed to provide an explanation for the increased ACTH, and ultimately a positron emission tomography/computed tomography (PET/CT) scan using a relatively new radiotracer, 68Ga-labeled 1,4,7,10-tetraazacyclododecane- N,N ′, N ′′, N ′′′ - tetraacetic acid-d-Phe1-Tyr3-octreotide (68Ga-DOTATOC), was performed (4). A 3.3-cm area in the head of the pancreas with an increased uptake of radiotracer was observed (Fig. 1). In light of the persistently increased ACTH concentration, this finding raised the suspicion of a pancreatic ACTH-secreting neuroendocrine tumor, a rare ectopic source of ACTH (3). Although MRI and conventional CT evaluations did not confirm the presence of a tumor, the patient was offered immediate surgical treatment. The patient declined the offer and subsequently sought second and third opinions at medical facilities in 2 different countries. In both facilities, a neuroendocrine tumor was deemed the likely cause of his problems, and surgery was again suggested. Wishing minimally invasive treatment, the patient contacted the Interventional Centre at our hospital, which offers laparoscopic resection of the pancreas. Fig. 1. 68Ga-DOTATOC PET/CT scan from June 2009 showing increased uptake of radiotracer in the processus uncinatus of the pancreas (arrow), with a maximum standardized uptake value (SUVmax) of 9. Physiological accumulation in the liver (L) and kidneys (K). ### QUESTIONS TO CONSIDER 1. Why …

The Detection of Hamster Connexins: A Comparison of Expression Profiles with Wild-Type Mouse and the Cancer-Prone Min Mouse

The open reading frames of 17 connexins from Syrian hamster (using tissues) and 16 connexins from the Chinese hamster cell line V79, were fully (Cx30, Cx31, Cx37, Cx43 and Cx45) or partially sequenced. We have also detected, and partially sequenced, seven rat connexins that previously were unavailable. The expression of connexin genes was examined in some hamster organs and cultured hamster cells, and compared with wild-type mouse and the cancer-prone Min mouse. Although the expression patterns were similar for most organs and connexins in hamster and mouse, there were also some prominent differences (Cx29 and 30.3 in testis; Cx31.1 and 32 in eye; Cx46 in brain, kidney and testis; Cx47 in kidney). This suggests that some connexins have species-specific expression profiles. In contrast, there were minimal differences in expression profiles between wild type and Min mice. Species-specific expression profiles should be considered in attempts to make animal models of human connexin-associated diseases.

Combining Anti-TNF-α and Vedolizumab in the Treatment of Inflammatory Bowel Disease: A Case Series

Background Anti-tumor necrosis factor α (anti-TNF-α) is important in the treatment of inflammatory bowel disease, but some patients experience only a partial response. In these patients, a combination of anti-TNF-α and vedolizumab (VDZ) may act as a bridge until the full VDZ effect occurs. At present, clinical data on combination treatment with anti-TNF-α and VDZ are not available. The aim of this case series was to evaluate the safety and clinical response of combination therapy with anti-TNF-α and VDZ in clinical practice. Methods All patients started on combination treatment with anti-TNF-α and VDZ from November 2015 to July 2016 were prospectively followed for at least 12 months. Results Six patients with ulcerative colitis and four patients with Crohns disease received combination treatment. These patients were followed for a median of 1712-20 months. No more adverse events than expected with anti-TNF-α alone were observed during combination treatment. At the end of follow-up, all patients were in clinical remission, and 8 patients could discontinue anti-TNF-α treatment and receive VDZ monotherapy. Two of the patients with Crohns disease required combination treatment throughout follow-up to obtain sustained remission. Conclusion Our findings suggest that combination treatment with anti TNF-α and VDZ is safe and might represent a long-term treatment option in selected patients.

TD-12 workshop report: characterization of monoclonal antibodies to neuron-specific enolase.

Twelve antibodies to neuron-specific enolase (NSE) have been evaluated by four working groups. Human brain γγ-enolase, neuroblastoma-derived αγ-enolase, and recombinant γγ-enolase were used to determine antibody specificity and binding kinetics. All antibodies were found to be specific for the γ-isoform. It was possible to assign 11 of the antibodies to at least five epitope groups based on cross-inhibition experiments, QCM and SPR technology, and immunoassay combinations. Antibodies 9601 and 9602 showed the highest affinity for both native and recombinant γγ-enolase. Immunometric assays for both γγ- and αγ-enolase could be made by pairing 9601 with most of the other ISOBM antibodies. Antibodies differed in their ability to recognize native αγ-enolase, native γγ-enolase, and recombinant γγ-enolase. Some immunometric assay combinations appear to favor the detection of heterodimeric αγ-enolase over the homodimeric γγ-enolase. Although the majority of the antibodies failed to detect human NSE or recombinant NSE in Western blots, mAb 9601 recognized both, while E17 and 18E5 were specific for human NSE.