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Objectives Patients with Systemic Lupus Erythematosus are known to have dysregulated immune responses and may have reduced response to vaccination against COVID-19 while being at risk of severe COVID-19 disease. The aim of this study was to identify whether vaccine responses were attenuated in SLE and to assess disease- and treatment-specific associations. Methods Patients with SLE were matched by age, sex and ethnic background to healthcare worker healthy controls (HC). Anti-SARS-CoV-2 spike glycoprotein antibodies were measured at 4–8 weeks following the second COVID-19 vaccine dose (either BNT162b2 or ChAdOx1 nCoV-19) using a CE-marked combined ELISA detecting IgG, IgA and IgM (IgGAM). Antibody levels were considered as a continuous variable and in tertiles and compared between SLE patients and HC and associations with medication, disease activity and serological parameters were determined. Results Antibody levels were lower in 43 SLE patients compared to 40 HC ( p < 0.001). There was no association between antibody levels and medication, lupus disease activity, vaccine type or prior COVID infection. Higher serum IgA, but not IgG or IgM, was associated with being in a higher anti-SARS-CoV-2 antibody level tertile (OR [95% CI] 1.820 [1.050, 3.156] p = 0.033). Similarly, higher lymphocyte count was also associated with being in a higher tertile of anti-SARS-CoV-2 (OR 3.330 [1.505, 7.366] p = 0.003) Conclusion Patients with SLE have lower antibody levels following 2 doses of COVID-19 vaccines compared to HC. In SLE lower lymphocyte counts and serum IgA levels are associated with lower antibody levels post vaccination, potentially identifying a subgroup of patients who may therefore be at increased risk of infection.

BACKGROUND AND AIMS A variety of auto-antibody assays are available as part of the clinical care of patients with liver disease. We sought to better understand the clinical utility of immune serological testing in patients with primary biliary cholangitis (PBC). METHODS We retrospectively analysed data from 2846 patients investigated for liver disease at a UK liver centre between 2001 and 2017. A total of 499 patients with PBC were identified. Immune serology results were examined for their diagnostic utility and prognostic significance to predict transplant-free survival. RESULTS Antimitochondrial antibodies (AMAs) were specific (94.5%) and sensitive (85.6%) for PBC; antinuclear antibodies (ANAs) against glycoprotein 210 (gp210) and sp100 were specific (>98%) but not sensitive (

Genome sequencing is a powerful tool for identifying SARS-CoV-2 variant lineages; however, there can be limitations due to sequence dropout when used to identify specific key mutations. Recently, ThermoFisher Scientific has developed genotyping assays to help bridge the gap between testing capacity and sequencing capability to generate real-time genotyping results based on specific variants. Over a 6-week period during the months of April and May 2021, we set out to assess the ThermoFisher TaqMan mutation panel genotyping assay, initially for three mutations of concern and then for an additional two mutations of concern, against SARS-CoV-2-positive clinical samples and the corresponding COVID-19 Genomics UK Consortium (COG-UK) sequencing data. We demonstrate that genotyping is a powerful in-depth technique for identifying specific mutations, is an excellent complement to genome sequencing, and has real clinical health value potential, allowing laboratories to report and take action on variants of concern much more quickly.

Variants of SARS-CoV-2 may evade natural and vaccine induced immunity and monoclonal antibody immunotherapeutics. There is an urgent need to know how well antibodies, induced by healthy and Clinically Extremely Vulnerable (CEV) patients, will bind and thus help reduce transmission and severity of infection from variants of concern (VOC). This study determines the cross-reactive binding of serum antibodies obtained prior to and 28 days after a third vaccination in three cohorts; a health care worker cohort who received three doses of Pfizer-BioNtech (PPP), a cohort of CEV patients received two doses of the AstraZeneca-ChAdOx1-nCoV-19 (AAP) vaccine, followed by a third PFZ vaccine and a haemodialysis cohort that had a mixture of two AZ or PFZ vaccines followed by a PFZ booster. Six months post second vaccine there was evidence of antibody waning with 58.9% of individuals in the HD cohort seropositive against Wuhan, 34.4% Delta and 62.2% Omicron strains. For the AAP cohort, equivalent figures were 62.5%, 45.8% and 91.7% and the PPP cohort 92.2%, 90% and 91.1%. Post third dose vaccination there were universal increases in seropositivity and median optical density. For the HD cohort, 98.8% were seropositive to the Wuhan strain, 97.6% against Delta and 100% against Omicron strains. For the PPP and AAP cohorts, 100% were seropositive against all 3 strains. Lastly, we examined the WHO NIBSC 20/136 standard and there was no loss of antibody binding to either VOC. Similarly, a dilution series of Sotrovimab (GSK) found this therapeutic monoclonal antibody bound similarly to all VOC.HighlightsIgG anti-SARS-CoV-2 Omicron spike glycoprotein antibody levels were high in 100% of health care workers (HCW), a general practice population considered clinically extremely vulnerable (CEV) and haemodialysis patients (HD) 4 weeks after a third SARS-CoV-2 vaccine dose (Pfizer-BioNtech-PFZ).For both Delta and Omicron variant spike glycoproteins these antibody levels were highest in the CEV cohort who had previously received two doses of AstraZeneca ChAdOx1 nCoV-19 vaccine (AAP), lower in HCW who had previously received two doses of PFZ (PPP) and lowest in HD who had a mix of vaccines for the first and second dosePrior to this third vaccine dose and 6 months post second vaccine dose there was evidence of significant waning of antibodies against VOC.

Genome sequencing is a powerful tool for identifying SARS-CoV-2 variant lineages, however there can be limitations due to sequence drop-out when used to identify specific key mutations. Recently, Thermo Fisher Scientific have developed genotyping assays to help bridge the gap between testing capacity and sequencing capability to generate real-time genotyping results based on specific variants. Over a 6-week period during the months of April and May 2021, we set out to assess the Thermo Fisher TaqMan Mutation Panel Genotyping Assay, initially for three mutations of concern and then an additional two mutations of concern, against SARS-CoV-2 positive clinical samples and the corresponding COG-UK sequencing data. We demonstrate that genotyping is a powerful in-depth technique for identifying specific mutations, an excellent complement to genome sequencing and has real clinical health value potential allowing laboratories to report and action variants of concern much quicker.

Detecting antibody responses during and after SARS‐CoV‐2 infection is essential in determining the seroepidemiology of the virus and the potential role of antibody in disease. Scalable, sensitive and specific serological assays are essential to this process. The detection of antibody in hospitalized patients with severe disease has proven relatively straightforward; detecting responses in subjects with mild disease and asymptomatic infections has proven less reliable. We hypothesized that the suboptimal sensitivity of antibody assays and the compartmentalization of the antibody response may contribute to this effect. We systematically developed an ELISA, optimizing different antigens and amplification steps, in serum and saliva from non‐hospitalized SARS‐CoV‐2‐infected subjects. Using trimeric spike glycoprotein, rather than nucleocapsid, enabled detection of responses in individuals with low antibody responses. IgG1 and IgG3 predominate to both antigens, but more anti‐spike IgG1 than IgG3 was detectable. All antigens were effective for detecting responses in hospitalized patients. Anti‐spike IgG, IgA and IgM antibody responses were readily detectable in saliva from a minority of RT‐PCR confirmed, non‐hospitalized symptomatic individuals, and these were mostly subjects who had the highest levels of anti‐spike serum antibodies. Therefore, detecting antibody responses in both saliva and serum can contribute to determining virus exposure and understanding immune responses after SARS‐CoV‐2 infection., This manuscript describes the development of a highly sensitive ELISA, optimizing different antigens and amplification steps, in serum and saliva from non‐hospitalized SARS‐CoV‐2‐infected subjects. Using a trimeric spike glycoprotein, rather than nucleocapsid, enabled detection of responses in individuals with mild‐to‐moderate infection. The detection of antibodies in both serum and saliva can contribute to determining virus exposure and understanding immune responses to SARS‐CoV‐2.

Background Frequently SARS-CoV-2 results in mild or moderate disease with potentially lower concentrations of antibodies compared to those that are hospitalised. Here, we validated an ELISA using SARS-CoV-2 trimeric spike glycoprotein, with targeted detection of IgG, IgA and IgM (IgGAM) using serum and dried blood spots (DBS) from adults with mild or moderate disease. Methods Targeting the SARS-CoV-2 trimeric spike, a combined anti-IgG, IgA and IgM serology ELISA assay was developed using 62 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 624 COVID-19 negative samples. The assay was validated using 73 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 359 COVID-19 negative serum samples with an additional 81 DBSs. The assay was further validated in 226 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 426 COVID-19 negative clinical samples. Results A sensitivity and specificity of 98.6% (95% CI, 92.6–100.0), 98.3% (95% CI, 96.4–99.4), respectively, was observed following validation of the SARS-CoV-2 ELISA. No cross-reactivities with endemic coronaviruses or other human viruses were observed, and no change in results were recorded for interfering substances. The assay was stable at temperature extremes and components were stable for 15 days once opened. A matrix comparison showed DBS to correlate with serum results. Clinical validation of the assay reported a sensitivity of 94.7% (95% CI, 90.9–97.2%) and a specificity of 98.4% (95% CI, 96.6–99.3%). Conclusions The human anti-IgGAM SARS-CoV-2 ELISA provides accurate and sensitive detection of SARS-CoV-2 antibodies in non-hospitalised adults with mild or moderate disease. The use of dried blood spots makes the assay accessible to the wider community.

Lateral flow devices (LFDs) are quickly being implemented for use in large-scale population surveillance programs for SARS-CoV-2 infection in the United Kingdom. These programs have been piloted in city-wide screening in the city of Liverpool and are now being rolled out to support care home visits and the return home of University students for the Christmas break. Here, we present data on the performance of LFDs to test almost 8,000 students at the University of Birmingham between December 2 and December 9, 2020. The performance is validated against almost 800 samples using PCR performed in the University Pillar 2 testing lab and theoretically validated on thousands of Pillar 2 PCR testing results performed on low-prevalence care home testing samples. Our data show that LFDs do not detect infections presenting with PCR Ct values over 29 to 30 as determined using the Thermo Fisher TaqPath asssay. This may be of particular importance in detecting individuals that are either at the early, or late stages of infection, and reinforces the need for frequent, recurrent testing., Antigen-detecting lateral flow tests are faster than PCR tests in detecting SARS-CoV-2 infection and are being implemented for use in large-scale population surveillance in the UK. An evaluation of the performance of the lateral flow devices, validated using PCR, concludes that lateral flow devices do not detect infections presenting with higher PCR Ct values, reinforcing the need for frequent, recurrent testing.

A SARS-CoV-2 variant B1.1.7 containing mutation Δ69/70 has spread rapidly in the United Kingdom and shows an identifiable profile in ThermoFisher TaqPath RT-qPCR, S gene target failure (SGTF). We analyzed recent test data for trends and significance. Linked cycle threshold (Ct) values for respiratory samples showed that a low Ct for ORF1ab and N were clearly associated with SGTF. Significantly more SGTF samples had higher inferred viral loads between 1×107 and 1×108. Our conclusion is that patients whose samples exhibit the SGTF profile are more likely to have high viral loads, which may explain higher infectivity and rapidity of spread.

Birmingham University Turnkey laboratory is part of the Lighthouse network responsible for testing clinical samples under the UK government ‘Test & Trace’ scheme. Samples are analysed for the presence of SARS-CoV-2 in respiratory samples using the Thermofisher TaqPath RT-QPCR test, which is designed to co-amplify sections of three SARS-CoV-2 viral genes.Since more recent information became available regarding the presence of SARS-CoV-2 variants of concern (S-VoC), which can show a suboptimal profile in RT-QPCR tests such as the ThermoFisher TaqPath used at the majority of Lighthouse laboratories, we analysed recently published data for trends and significance of the S-gene ‘dropout’ variant.Results showed that:the population of S-gene dropout samples had significantly lower median Ct values of ORF and N-gene targets compared to samples where S-gene was detectedon a population basis, S-gene dropout samples clustered around very low Ct values for ORF and N targetslinked Ct values for individual samples showed that a low Ct for ORF and N were clearly associated with an S-dropout characteristicwhen conservatively inferring relative viral load from Ct values, approximately 35% of S-dropout samples had high viral loads between 10 and 10,000-fold greater than 1 × 106, compared to 10% of S-positive samples.This analysis suggests that patients whose samples exhibit the S-dropout profile in the TaqPath test are more likely to have high viral loads at the time of sampling. The relevance of this to epidemiological reports of fast spread of the SARS-CoV-2 in regions of the UK is discussed.

Lateral flow devices are quickly being implemented for use in large scale population surveillance programs for SARS-CoV-2 infection in the United Kingdom. These programs have been piloted in city wide screening in the city of Liverpool, and are now being rolled out to support care home visits and the return home of University students for the Christmas break. Here we present data on the performance of Lateral Flow devices to test almost 8,000 students at the University of Birmingham between December 2nd and December 9th 2020. The performance is validated against almost 800 samples using PCR performed in the University Pillar 2 testing lab, and theoretically validated on thousands of Pillar 2 PCR testing results performed on low-prevalence care home testing samples. Our data shows that Lateral Flow Devices do not detect infections presenting with PCR Ct values over 29-30, meaning that only 3.2% (95% CI 0.6% to 15.6%) of total cases in the student population were detected, but that as many of 85% of cases tested in the Pillar 2 PCR lab would have been detected theoretically

BackgroundFrequently SARS-CoV-2 results in mild or moderate disease with potentially lower concentrations of antibodies compared to those that are hospitalised. Here, we validated an ELISA using SARS-CoV-2 trimeric spike glycoprotein, with targeted detection of IgG, IgA and IgM (IgGAM) using serum and dried blood spots (DBS) from adults with mild or moderate disease.MethodsTargeting the SARS-CoV-2 trimeric spike, a combined anti-IgG, IgA and IgM serology ELISA assay was developed using 62 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 624 COVID-19 negative samples. The assay was validated using 73 PCR-confirmed non-hospitalised COVID-19 and 359 COVID-19 negative serum samples with an additional 81 DBSs, and further validated in 226 PCR-confirmed non-hospitalised COVID-19 and 426 COVID-19 negative clinical samples.ResultsA sensitivity and specificity of 98.6% (95% CI, 92.6–100.0), 98.3% (95% CI, 96.4–99.4), respectively, was observed following validation of the SARS-CoV-2 ELISA. No cross-reactivities with endemic coronaviruses or other human viruses were observed, and no change in results were recorded for interfering substances. The assay was stable at temperature extremes and components were stable for 15 days once opened. A matrix comparison showed DBS to correlate with serum results. Clinical validation of the assay reported a sensitivity of 94.7% (95% CI, 90.9-97.2%) and a specificity of 98.4% (95% CI, 96.6-99.3%).ConclusionsThe human anti-IgGAM SARS-CoV-2 ELISA provides accurate and sensitive detection of SARS-CoV-2 antibodies in non-hospitalised adults with mild or moderate disease. The use of dried blood spots makes the assay accessible to the wider community.Supplementary MaterialNo

BackgroundDetecting antibody responses during and after SARS-CoV-2 infection is essential in determining the seroepidemiology of the virus and the potential role of antibody in disease. Scalable, sensitive and specific serological assays are essential to this process. The detection of antibody in hospitalized patients with severe disease has proven straightforward; detecting responses in subjects with mild disease and asymptomatic infections has proven less reliable. We hypothesized that the suboptimal sensitivity of antibody assays and the compartmentalization of the antibody response may contribute to this effect.MethodsWe systemically developed an ELISA assay, optimising different antigens and amplification steps, in serum and saliva from symptomatic and asymptomatic SARS-CoV-2-infected subjects.ResultsUsing trimeric spike glycoprotein, rather than nucleocapsid enabled detection of responses in individuals with low antibody responses. IgG1 and IgG3 predominate to both antigens, but more anti-spike IgG1 than IgG3 was detectable. All antigens were effective for detecting responses in hospitalized patients. Anti-spike, but not nucleocapsid, IgG, IgA and IgM antibody responses were readily detectable in saliva from non-hospitalized symptomatic and asymptomatic individuals. Antibody responses in saliva and serum were largely independent of each other and symptom reporting.ConclusionsDetecting antibody responses in both saliva and serum is optimal for determining virus exposure and understanding immune responses after SARS-CoV-2 infection.FundingThis work was funded by the University of Birmingham, the National Institute for Health Research (UK), the NIH National Institute for Allergy and Infectious Diseases, the Bill and Melinda Gates Foundation and the University of Southampton.

Background In January 2020 reports of unidentified severe respiratory illness were described in Wuhan, China. A rapid expansion in cases affecting most countries around the globe led to major changes in the way people live their daily lives. In the United Kingdom, the Department of Health and Social Care directed healthcare providers to establish additional resources to manage the anticipated surge in cases that could overwhelm the health services. A priority area was testing for SARS-CoV-2 RNA and its detection by qualitative RT-PCR. Design A laboratory workflow twinning research environment with clinical laboratory capabilities was implemented and validated in the University of Birmingham within 4 days of the project initiation. The diagnostic capability was centred on an IVD CE-marked RT-PCR kit and designed to provide surge capacity to the nearby Queen Elizabeth Hospital. The service was initially tasked with testing healthcare workers (HCW) using throat swabs, and subsequently the process investigated the utility of using saliva as an alternative sample type. Results Between the 8th April 2020 and the 30th April 2020, the laboratory tested a total of 1282 HCW for SARS-CoV-2 RNA in throat swabs. RNA was detected in 54 % of those who reported symptoms compatible with COVID-19, but in only 4% who were asymptomatic. Conclusion This capability was established rapidly and utilised a cold-chain free methodology, applicable to a wide range of settings, and which can provide surge capacity and support to clinical laboratories facing increasing pressure during periods of national crisis.

Introduction Immunoserologic investigation is of clinical use in the discrimination of liver disease of autoimmune aetiology from alternate causes. We sought to investigate the diagnostic utility of immune serology in patients investigated for liver disease. Method We analysed the immunoprofile of patients investigated for liver disease at a tertiary centre between 2001 and 2017. We compared Results for patients clinically coded with a diagnosis of autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), or primary sclerosing cholangitis (PSC) against those without, amongst patients investigated by our liver services. Overlap features (o/l) were included if clinically documented. Results We evaluated Results from 2874 patients. Patients with AIH (n=556; incl. o/l (19.3%)) were predominantly female (3 F: 1 M), with a bimodal age distribution at presentation (≈18, 62 years). Antinuclear (ANA) and smooth muscle antibodies (SMA) were both sensitive (92.3%, 86.6% respectively) for a diagnosis of AIH, but poorly specific (23.6%, 27.2%). Amongst patients with T1AIH, 39 patients had antibodies to soluble liver antigen (SLA). Of these, 36 (92%) had concordance to Ro-52 antibodies. 2.3% of patients with AIH had T2AIH, defined by antibodies to liver-kidney microsome-1 (LKM); of the 13 patients, 4 had SMA and 8 have ANA reactivity. Patients with PBC (n=527; incl. o/l (18.3%)) were primarily female (9 F: 1 M), and in their 6th decade (mean=56 years). Anti-mitochondrial antibody (AMA) testing was both sensitive (70.6%) and specific (91.2%). In patients who were AMA negative at testing, anti-glycoprotein 210 (gp210) (sens 40.7%, spec 95%) and anti-SP100 (sens 40.3%, spec 96.3%) proved useful diagnostic adjuncts. Patients with PSC (n=291; incl. o/l (10.1%)) were predominantly male (3 M: 2 F) with a bimodal age distribution at presentation (≈25, 58 years). Perinuclear anti neutrophil cytoplasmic antibody was seemingly specific for PSC (93.9%), as compared to non-autoimmune liver patients, and found in 23.3% of patients. To differentiate between PSC and AIH, anti-SLA, -LC1, -Ro-52, ds-DNA and f-actin all had a PPV >95% for AIH;>85% in patients who were negative for SMA. Similarly, to distinguish PBC from PSC, AMA, anti Ro-52, -gp210 and -SP100 all have a PPV >90% for PBC; this was also true for anti-Ro52 and -SP100 in patients who were AMA-negative. Conclusion The optimal use of immunoserology requires careful evaluation of test parameters in the population served by a liver disease programme.

Background High-throughput high-sensitivity ELISAs for autoantibodies associated with CTD, such as extractable nuclear antigens (ENA), are used widely. Anti-Jo-1 (anti-histidyl-tRNA synthetase), one of this panel, is believed to confer a poor prognosis due to an association with interstitial lung disease (ILD) and myositis. Objectives To describe: the pattern of anti-ENA positive tests; frequency of repeated requests; stability and repeatability of anti-Jo-1 tests; clinical characteristics of anti-Jo-1 +ves compared with controls; and diagnostic value of anti-Jo-1 for ILD. Methods All anti-ENA test requests, from any hospital department, between Jan 2013 and Dec 2014 were identified. Serum samples are screened for ENA (Quanta Lite® ENA profile, Inova Diagnostics) and positive samples have specific ENA antibodies levels quantified. Data from anti-Jo-1 positive patients and controls was extracted from electronic records allowing a minimum of 12 months after first test. Results 4009 samples from 3581 patients were tested. The first sample tested, chronologically, was designated test of interest. 616 (17.2%) patients were anti-ENA screen +ve, and 40 (1.1%) anti-Jo-1 +ve (>20 AU/mL). Anti-ENA tests were done more than once for 350/3581 (9.8%) patients (428/4009 (10.7%) samples) and for 7/40 (17.5%) of anti-Jo-1 +ve patients. The median interval between 1st and 2nd requests: 124 days (IQR 233 days). The Table shows data for anti-Jo-1 patients and randomly selected ENA -ve controls. The frequency of ILD, myositis and Raynaud9s was comparable. Sensitivity and specificity of Jo-1 for ILD, a key feature of “anti-synthetase syndrome”, were 50% (CI 19–81%) and 68% (CI 59–77%) respectively. Positive predictive value 12.5% (CI 4 to 27%) and negative predictive value 93.8% (CI 86–98%). Of patients with the highest anti-Jo1 titres (≥40 AU/mL, 10/40 patients, 25%): 3 had ILD, 1 myositis and 2 had a malignancy (disseminated melanoma and CML). Bland-Altman plots show that anti-Jo-1 values remained stable when patients were re-tested at another time but re-testing available stored samples from +ve patients showed important variation (Figure). Conclusions Anti-Jo-1 is uncommon in a heterogenous hospital population and is only weakly predictive for ILD. When tested repeatedly levels remain stable over many months. Repeated testing for anti-ENA is common and potentially unnecessary. Controls over repeated requests could yield cost savings. Disclosure of Interest None declared

Background Polyclonal FLCs can be used as a biomarker of inflammation and immune activation in a range of diseases. This study evaluated the performance of new FLC ELISAs (Seralite FLC ELISA) for the quantitation of polyclonal κ and λ FLC, including comparisons to existing assays. Methods Technical performance was assessed for the ELISA and reference ranges were generated using healthy donor serum (N = 91). Patients with a range of conditions associated with polyclonal FLC dysregulation (N = 164) were measured across platforms. Results The ELISAs generated references ranges of: 8.72–23.0 mg/L κ FLC, and 8.52–25.24 mg/L for λ FLC. ELISAs demonstrated linearity across the calibration range and intra-assay (≤ 8.7%) and inter-assay (≤ 12.3%) imprecision was low. The limit of detection was 0.63 mg/L for κ and 0.57 mg/L for λ FLC. Minimal cross-reactivity was observed for interference agents, alternate FLC and whole immunoglobulin (median change ≤3.6 mg/L). Assays showed good batch-to-batch consistency. For patient samples, methods generated different κ and λ FLC concentrations and differences were seen between methods for the number of patients classified as below, with and above references ranges for κ and λ FLC. There was no significant difference in the FLC sum between the different techniques. Conclusions The ELISAs displayed good analytical and technical performance. The quantification of individual κ and λ FLC appears inherently different between platforms. These differences are attenuated if using the FLC sum, which was similar between methods and provided agreement in relation to patients having normal or elevated FLCs.

Item does not contain fulltext BACKGROUND: Serum free light chains (FLC) are sensitive biomarkers used for the diagnosis and management of plasma cell dyscrasias, such as multiple myeloma (MM), and are central to clinical screening algorithms and therapy response criteria. We have developed a portable, near-patient, lateral-flow test (Seralite(R)) that quantitates serum FLC in 10 min, and is designed to eliminate sample processing delays and accelerate decision-making in the clinic. METHODS: Assay interference, imprecision, lot-to-lot variability, linearity, and the utility of a competitive-inhibition design for the elimination of antigen-excess ('hook effect') were assessed. Reference ranges were calculated from 91 healthy donor sera. Preliminary clinical validation was conducted by retrospective analysis of sera from 329 patients. Quantitative and diagnostic results were compared to Freelite(R). RESULTS: Seralite(R) gave a broad competitive-inhibition calibration curve from below 2.5 mg/L to above 200 mg/L, provided good assay linearity (between 1.6 and 208.7 mg/L for kappa FLC and between 3.5 and 249.7 mg/L for lambda FLC) and sensitivity (1.4 mg/L for kappa FLC and 1.7 mg/L for lambda FLC), and eliminated anomalous results from antigen-excess. Seralite(R) gave good diagnostic concordance with Freelite(R) (Roche Hitachi Cobas C501) identifying an abnormal FLC ratio and FLC difference in 209 patients with newly diagnosed MM and differentiating these patients from normal healthy donors with polyclonal FLC. CONCLUSIONS: Seralite(R) sensitively quantitates FLC and rapidly identifies clinical conditions where FLC are abnormal, including MM.

Objectives To compare the antibody response to a licenced polysaccharide and glycoconjugate vaccine against encapsulated bacteria in HIV-infected and HIV-uninfected adults in the UK Design Prospective cohort study Setting UK teaching hospital Participants 211 HIV-infected adults and 73 HIV-uninfected adults. Entry criteria: over 18 years of age. Exclusion criteria: previous pneumococcal, Hib or MenC vaccination. Interventions Vaccination with a 23-valent pneumococcal polysaccharide vaccine (PPV) and Haemophilus influenzae b/meningococcal C polysaccharide-tetanus toxoid conjugate vaccine (Hib/MenC-TT). Main outcome measures Concentration of IgG antibody responses to 12 pneumococcal, Hib and MenC polysaccharides and percentages of participants protected post-vaccination in HIV-infected participants compared with HIV-uninfected participants. Results Median IgG responses to Hib/MenC-TT were not significantly different between HIV-infected (3.74 and 2.88 g/ml) and HIV-uninfected groups (4.85 and 4.56 g/ml). PPV induced median IgGs above a 1.3 g/ml threshold for 10/12 serotypes among HIV-uninfected, and 5/12 in HIV-infected participants. HIV-uninfected adults had higher median post-vaccination IgGs than HIV-infected for serotypes 1, 7F, 18C and 23F (p Conclusions In a UK adult HIV-infected population, Hib/MenC-TT induced similar IgG responses to HIV-uninfected adults, while PPV induced comparatively poor responses. Lack of association with CD4 count or viral load supports early immunization. Further studies are required to guide vaccination policy in HIV-infected patients.

BACKGROUND Mast cell activation can lead to nonclassical activation of the Renin-Angiotensin-Aldosterone System. However, the relevance of this to human chronic kidney disease is unknown. We assessed the association between serum tryptase, a product of mast cell activation, and progression to end-stage renal disease or mortality in patients with advanced chronic kidney disease. We stratified patients by use of angiotensin-converting enzyme inhibitors/angiotensin receptor II blockers (ACEi/ARB). MATERIALS AND METHODS This was a prospective cohort study of 446 participants recruited into the Renal Impairment in Secondary Care study. Serum tryptase was measured at recruitment by sandwich immunoassay. Cox regression analysis was undertaken to determine variables associated with progression to end-stage renal disease or death. RESULTS Serum tryptase concentration was independently associated with progression to end-stage renal disease but not with death. In patients treated with ACEi or ARB, there was a strong independent association between higher tryptase concentrations and progression to end-stage renal disease; when compared to the lowest tertile, tryptase concentrations in the middle and highest tertiles had hazard ratios [HR] of 5·78 (95% confidence interval [CI] 1·19-28·03, P = 0·029) and 6·19 (95% CI 1·49-25·69, P = 0·012), respectively. The other independent risk factors for progression to end-stage renal disease were lower age, male gender, lower estimated glomerular filtration rate and higher urinary albumin creatinine ratio. CONCLUSION Elevated serum tryptase concentration is an independent prognostic factor for progression to end-stage renal disease in patients with chronic kidney disease who are receiving treatment with an ACEi or ARB.

Syndecan-1 (CD138) is a heparin sulphate proteoglycan that is over expressed on the surface of both normal and malignant plasma cells and actively shed from the cell surface (soluble syndecan-1). Soluble syndecan-1 has been shown to be an independent prognostic factor in myeloma but its role in prognostic classification requires further investigation. We have retrospectively measured soluble syndecan-1 in 324 presentation samples and 154 plateau phase samples from the UK Medical Research Council Myeloma VIth trial. Log-rank analysis showed that the presentation value of soluble syndecan-1 is a highly significant prognostic factor when assessing survival from entry (chi2=14.92, P

The measurement of antibody responses to vaccination is useful in the assessment of immune status in suspected immune deficiency. Previous reliance on enzyme-linked immunoabsorbent assays (ELISA) has been cumbersome, time-consuming and expensive. The availability of flow cytometry systems has led to the development of multiplexed assays enabling simultaneous measurement of antibodies to several antigens. We optimized a flow cytometric bead-based assay to measure IgG and IgM concentrations in serum to 19 antigens contained in groups of bacterial subunit vaccines: pneumococcal vaccines, meningococcal vaccines, Haemophilus influenzae b (Hib), and tetanus and diphtheria toxoid vaccines. 89-SF was employed as the standard serum. The assay was used to determine specific antibody levels in serum from 193 healthy adult donors. IgG and pneumococcal IgM antibody concentrations were measurable across 3 log10 ranges encompassing the threshold protective IgG antibody levels for each antigen. There was little interference between antibody measurements by the 19-plexed assay compared with monoplexed assays, and a lack of cross-reactive IgG antibody, but evidence for cross-reacting IgM antibody for 3/19 pneumococcal antigens. 90th centile values for 15/19 IgG concentrations and 12/12 IgM concentrations of the 193 adult sera were within these ranges and percentages of sera containing protective IgG antibody levels varied from 4% to 95% depending on antigen. This multiplexed assay can simultaneously measure antibody levels to 19 bacterial vaccine antigens. It is suitable for use in standard clinical practice to assess the in vivo immune response to test vaccinations and measure absolute antibody levels to these antigens.

Background Monoclonal free light chains (FLCs) frequently cause rapidly progressive renal failure in patients with multiple myeloma. Immunoassays which provide quantitative measurement of FLCs in serum, have now been adopted into screening algorithms for multiple myeloma and other lymphoproliferative disorders. The assays indicate monoclonal FLC production by the presence of an abnormal κ to λ FLC ratio (reference range 0.26–1.65). Previous work, however, has demonstrated that in patients with renal failure the FLC ratio can be increased above normal with no other evidence of monoclonal proteins suggesting that in this population the range should be extended (reference range 0.37–3.1). This study evaluated the diagnostic sensitivity and specificity of the immunoassays in patients with severe renal failure. Methods Sera from 142 patients with new dialysis-dependent renal failure were assessed by serum protein electrophoresis (SPE), FLC immunoassays and immunofixation electrophoresis. The sensitivity and specificity of the FLC ratio's published reference range was compared with the modified renal reference range for identifying patients with multiple myeloma; by receiver operating characteristic curve analysis. Results Forty one patients had a clinical diagnosis of multiple myeloma; all of these patients had abnormal serum FLC ratios. The modified FLC ratio range increased the specificity of the assays (from 93% to 99%), with no loss of sensitivity. Monoclonal FLCs were identified in the urine from 23 of 24 patients assessed. Conclusion Measurement of serum FLC concentrations and calculation of the serum κ/λ ratio is a convenient, sensitive and specific method for identifying monoclonal FLC production in patients with multiple myeloma and acute renal failure. Rapid diagnosis in these patients will allow early initiation of disease specific treatment, such as chemotherapy plus or minus therapies for direct removal of FLCs.

Introduction Monoclonal gammopathies are a disparate group of diseases from benign to malignant which are characterised by the proliferation of a single B cell clone that produces a homogeneous monoclonal immunoglobulin (M-Ig). The method of detection and quantification of the M-Ig will depend upon whether it is an intact immunoglobulin or present as serum free light chain only. Historically serum (SPEP) and urine (UPEP) electrophoresis were considered the gold standard for identifying intact M-Ig and FLC respectively. In 2001 the introduction of the Freelite test changed the diagnostic and monitoring paradigm. The assay is now recommended as a tool to diagnose and monitor patients with B cell disorders. However, the assay is sometimes confused with monospecific immunoassays for measuring total kappa and total lambda. Here we compare kappa & lambda Freelite with total kappa & lambda immunoassays alongside SPEP as tools to identify patients with monoclonal gammopathies. Materials and Methods Sera from 102 blood donors (55 males and 47 females, age range 18-67 years) and 103 patients with light chain associated gammopathies (44 males and 59 females, age range 38 to 88 years, 60 kappa / 43 lambda)taken during the course of their treatment were available. The sera was analysed retrospectively with FreeliteTM (The Binding Site Ltd, Birmingham, UK) on a SPAPLUSand Total Kappa &Lambda nephelometricassays (Beckman Coulter, USA) on an Immage.Monoclonality was identified by results falling outside of manufacturers normal ratio ranges (Freelite 0.256-1.65, Total light chain 1.53-3.29). Serum protein electrophoresis was performed and unexpectedly positive or negative results were assessed using immunofixation on the Hydrasys electrophoretic system (Sebia, France). Results Monoclonal production was identified in 80/103 light chain associated gammopathiesby Freelite, negative IFE confirmed the absence of monoclonal protein in 22/23 patients with normal FLC kappa/lambda ratios and 1/23 patients had an IgG lambda intact immunoglobulin. SPEP was positive in 30/103 patients, with total kappa/lambda immunoassays detecting monoclonal protein in just 26/103 samples. Freelite was positive in 6/102, SPEP in 2/102 and total kappa/lambda in 8/102 normal blood donor sera. Interestingly, in 1 patient with an abnormal FLC ratio and total kappa/lambda result had a lambda light chain identified using IFE.Comparisons between the performances of Freelite, Freelite + SPEP, Total kappa/lambda and total kappa/lambda + SPEP are shown in table 1). Conclusion In keeping with Kyle et al (1999) our study confirms the limitations of total kappa / lambda assays as tools to identify M-Igs. This is the first study looking to apply the recommended algorithm of Freelite + SPEP to the total kappa/lambda assays. The addition of SPEP to total kappa/lambda assays improved the performance to detect abnormalities, but even combined they were neither as sensitive, specific or accurate as the Freelite assay. Given the limitations of the total light chain assays identified in our study, it is important that physicians are aware of which assay is being utilised; one easy method to discriminate would be to look at the normal range of the assay being reported. Table 1: Comparison of Freelite, Freelite + SPEP, Total kappa/lambda, Total kappa/lambda + SPEP Freelite Freelite + SPEP Total Total + SPEP Sensitivity 77.67 81.55 25.24 43.69 Specificity 94.12 92.16 92.16 91.18 PPV 93.02 91.30 76.47 83.33 NPV 80.67 83.19 54.97 61.59 Accuracy 85.85 86.83 58.54 67.32 Disclosures No relevant conflicts of interest to declare.

Abstract 3964 Introduction: Monitoring multiple myeloma (MM) patients is required to help guide therapy and assess response. Currently the most commonly employed tests to monitor MM patients include serum protein electrophoresis (SPEP), immunofixation (IFE), 24hr urine and serum free light chain (FLC) analysis. Whilst electrophoretic tests are adequate for IgG MM, they may be inadequate for IgA MM where the monoclonal immunoglobulin co-migrates with other serum proteins (∼60% of cases). Recently the inclusion of FLC testing to identify patients in stringent complete response (sCR) has been recommended. Novel nephelometric reagents have become available that can quantify IgA kappa and IgA lambda immunoglobulins (HLC) in serum. Here we assess the use of these tests at maximum response to detect residual disease and comment on the prognostic value of sCR. Patients, materials and methods:196 IgA MM patient samples recruited from the MRC IX trial were assessed at maximum response. Briefly, patients were randomised on to intensive (I: induction therapy with CVAD or CTD followed by high-dose melphalan and ASCT) and non-intensive (NI: clodronate or zoledronic with MP or CTDa) arms. Median age was 59 years (range: 37–71) and 74 years (range: 65–89) for patients in the I and NI arms, respectively. 31% patients in the I arm and 39% in the NI arm presented with stage III disease. Samples were taken 3 months after autologous stem cell transplant or maximum response and analysed nephelometrically using serum FLC and HLC immunoassays. Ratios for both FLC and HLC were compared to normal ranges (FLC normal ratio= 0.256–1.65, IgAkappa/IgAlambda normal ratio=0.8–2.04). Additionally, isotype-matched immunoparesis was described as Results: 3 months post-therapy, patient responses were: I arm: progressive disease (PD): n=1( Response (3VGPR) was not associated with PFS in either arm (I, p=0.717; NI, p=0.236). By contrast, achievement of a sCR (p=0.013) was significantly associated with longer PFS in the I arm and tended towards significance in the NI arm (p=0.063). An abnormal HLC ratio was associated with shorter PFS in both arms (I, p=0.002; NI, p=0.032). In all patients achieving a 3VGPR, an abnormal HLC ratio was associated with shorter PFS (p>0.0001). Similarly, in patients achieving a 3CR an abnormal HLC ratio was also associated with shorter PFS (p=0.04). Furthermore, patients achieving a CR where both FLC and HLC ratios were normal had a significantly longer PFS than those with an abnormal FLC or HLC ratio (median PFS not reached v 18 months, p=0.007). Isotype-matched immunoparesis was associated with shorter PFS in all patients achieving a CR (p=0.061). By contrast, systemic immunoparesis of either IgG or IgM immunoglobulins were not associated with PFS (p=0.525 and p=0.964, respectively). Discussion: Novel therapies have dramatically improved MM patient outcomes, however improvements in the assessment of those outcomes has not followed a similar trajectory. Here we present data suggesting immunoglobulin HLC ratios may be better markers of residual disease than electrophoretic methods. In addition a response category based on normalisation of both FLC and HLC ratios may be more valuable than sCR. Finally, the identification of isotype matched immune reconstitution as a marker of outcome suggests a preferential suppression of immunoglobulin production not previously reported. Conclusion: Normalisation of the FLC and HLC ratio at maximum response is a better assessment of disease than IFE. Further work is required to validate these results and to assess FLC and HLC ratios against multi-parametric flow cytometry. Disclosures: Young: Binding Site: Employment.