Multiple Sera Research Articles

Serum CA125 and HE4 levels as predictors for optimal interval surgery and platinum sensitivity after neoadjuvant platinum-based chemotherapy in patients with advanced epithelial ovarian cancer.

BackgroundThe aim of this study is to evaluate a new tumour marker, HE4, and to compare it with CA125 in predicting optimal cytoreduction and response to chemotherapy. Thirty patients with advanced epithelial ovarian cancer and multiple sera harvested during neoadjuvant chemotherapy (NAC) were included.ResultsBased on ROC curves analysis, CA125 ≤ 75 UI/ml and HE4 ≤ 252 pmol/L after the 3rd cycles of NAC, with a sensitivity of 93.7 % and a specificity of 92.3 % (PPV = 93.7 % and NPV = 92.3 %), offered the best combination for predicting optimal cytoreduction. In addition, the HE4 value of 115 pmol/L is the best cut-off level for identifying platinum-sensitive patients.ConclusionsThe introduction of HE4 as a new tool for predicting platinum-sensitivity and interval optimal cytoreduction is promising.

Soluble B-Cell Maturation Antigen Mediates Tumor-Induced Immune Deficiency in Multiple Myeloma.

Reduced uninvolved immunoglobulin (Ig) levels are a hallmark of multiple myeloma. We previously showed that B-cell maturation antigen (BCMA) is solubilized and at high levels in multiple myeloma patient serum. We hypothesize that soluble BCMA binds B-cell-activating factor (BAFF) preventing its function to stimulate late B cells, and would result in lower polyclonal antibody levels in these patients. Mice were dosed with recombinant human BCMA (rhBCMA) and BCMA-BAFF complexes were analyzed in plasma, and its effects on antibody and Ig heavy chain mRNA levels determined. Using flow cytometry, BAFF binding to B cells was examined in the presence of rhBCMA and sera from multiple myeloma patients. In multiple myeloma sera, BCMA-BAFF complex formation and BCMA, IgA, IgG levels, and heavy-light chain isoform pair levels were determined. rhBCMA-BAFF complexes formed in immune-competent and deficient mice. Mice with human multiple myeloma xenografts, which contain plasma hBCMA and hBCMA-BAFF complexes, showed reduced plasma-free BAFF levels. rhBCMA administered to immune competent mice markedly reduced plasma IgA, IgG, and IgM levels and splenic Ig heavy chain mRNA levels. In serum from multiple myeloma patients, BCMA-BAFF complexes were detected and BAFF levels were reduced. Multiple myeloma patient sera containing BCMA prevented binding of BAFF to B cells. There is an inverse correlation between serum BCMA and uninvolved polyclonal Ig level in multiple myeloma patients. Our results show that soluble BCMA sequesters circulating BAFF, thereby preventing it from performing its signaling to stimulate normal B-cell and plasma cell development, resulting in reduced polyclonal antibody levels in multiple myeloma patients. Clin Cancer Res; 22(13); 3383-97. ©2016 AACR.

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Posttransplant (postTX) determination of de novo donor antigen specific antibody (DSA) has been monitored traditionally by conventional Luminex single antigen bead assays (LSAB-IgG). Correlation of DSA detected by the LSAB C1q binding assay and clinical outcomes remains to be investigated in our heart recipient population. Sera from 48 recipients transplanted between Jan 1994 and Oct 2012 were included in this study. All recipients were transplanted with a negative CDC xm with 3 having weak flow cytometric xms. Multiple postTX sera were tested by LSAB-IgG and for C1q binding and were shown to have DSAs. The postTX sera were received at routine clinic visits and at the time of biopsy. Biopsies were graded based on the new ISHLT grading scale. Two major patterns of DSA binding were observed:. 1) Persistent C1q binding DSA patterns, none of which reverted to C1q negative binding patterns (N=29) and 2). Persistent C1q negative binding patterns (N=19)(Table 1). The antibody patterns were shown to be persistent an average of 18 mo. (range 1 and 54 mo.). The predominant DSA specificity was class II: DQ alone (N=32), DRB3/4/5 (N=4), DQ+ DRB3 or 4 (N=6), DRB1 (N=1). Patients with the persistent C1q binding DSA had a higher incidence of AMR, CMR, NF-MACE, and a significantly higher incidence of CAV. Predominant class II, specifically anti-HLA DQ DSA patterns, were observed. No C1q positive pattern resolved to negative. Thus, some antibody patterns may be easier to resolve after therapy for rejection. Not all patients with the C1q binding DQ DSA profile have experienced a clinical event to date suggesting antibodies to non-HLA or a possible subclinical event.[figure1]

Implications of an indeterminate HIV antibody result - a case series

In Sri Lanka Immunoassays using either viral lysate (Western Blot) or recombinant/synthetic antigen (Line Immunoassay) for anti-HIV capture are still the preferred methods to confirm HIV infection. Three patients infected with HIV-1 presented with Acquired Immunodeficiency Syndrome (AIDS) defining illnesses. Laboratory tests were performed using the routine commercial kits on multiple sera of one patient and same sera from the other two. All patients were strongly positive on the Enzyme Linked Immuno Sorbent Assay (ELISA) test. Yet, HIV-1 infection could not be confirmed using the routine Line Immunoassay. Eventually HIV infection was confirmed in two patients using the Western blot assay but in one patient that was also indeterminate. We were unable to test further due to non-availability of other tests such as nucleic acid testing (NAT) assays to confirm the presence of HIV RNA. This highlights the fact that in resource poor countries, indeterminate results may delay the diagnosis of HIV, if only Line Immunoassays are available. Some end stage HIV/ AIDS patients may not produce antibodies to specific HIV antigens and may give indeterminate or negative results. DOI: http://dx.doi.org/10.4038/sljv.v2i1.5402 Sri Lanka Journal of Venereology Vol.2(1) 2009 pp.25-28

Differential Cytokine Release from Brain Microvascular Endothelial Cells Treated with Dexamethasone and Multiple Sclerosis Patient Sera

Objective: Multiple sclerosis (MS) is a neurodegenerative disorder of the central nervous system (CNS). Damage of the blood-brain barrier integrity is a key pathogenic event leading to the migration of lymphocytes into the CNS and subsequent demyelination. This process is tightly regulated by chemokines and cytokines which are target of therapeutic strategies in MS, such as anti-inflammatory glucocorticosteroid treatment. Here, we examine the effects of dexamethasone-treatment and MS patient sera on the expression of cytokines and chemokines in brain microvascular cell line, cEND in vitro. Methods: We conducted 96-well Mouse Cytokines and Receptors qPCR arrays to quantitatively compare the cytokine and chemokine expression profiles after treatment with dexamethasone. For selected cytokines, we studied the effects of pre-treatment with MS patient sera from active phase of disease (exacerbation) or in relapse (remission) in combination with dexamethasone. Results: After dexamethasone treatment, colony stimulating factor 3 (Csf3) and interleukin 17F (IL17f) were significantly up-regulated, whereas the chemokine (C-C motif) ligand 12 (CCL12/MCP-5), chemokine (C-X-C motif) receptor 3 (CXCR3) and kit oncogene (Kit) were significantly down-regulated. These results were confirmed in qRT-PCR using gene-specific primers. For Csf3 and CCL12 we analyzed the dexamethasone-mediated changes in protein levels secreted into the cell culture medium. Dexamethasone treatment increased the release of Csf3 into the culture medium and decreased the release of CCL12 by cEND. Additionally, we examined the effects of MS-patient sera on dexamethasone-induced cytokine secretion. Pretreatment with MS-patient serum from exacerbation phase augmented dexamethasone effects on Csf3 and CCL12 release in cEND cells. The expression of Csf3- and CCL12-receptors was demonstrated on protein and mRNA level in cEND cells. Conclusion: We identified Csf3 (G-Csf) and CCL12 as cytokines differentially regulated by dexamethasone on mRNA and protein level. This effect was even more pronounced after pretreatment with MS patient serum, especially from patients with acute relapses.

Designed Glucopeptides Mimetics of Myelin Protein Epitopes As Synthetic Probes for the Detection of Autoantibodies, Biomarkers of Multiple Sclerosis

We previously reported that CSF114(Glc) detects diagnostic autoantibodies in multiple sclerosis sera. We report herein a bioinformatic analysis of myelin proteins and CSF114(Glc), which led to the identification of five sequences. These glucopeptides were synthesized and tested in enzymatic assays, showing a common minimal epitope. Starting from that, we designed an optimized sequence, SP077, showing a higher homology with both CSF114(Glc) and the five sequences selected using the bioinformatic approach. SP077 was synthesized and tested on 50 multiple sclerosis patients' sera, and was able to detect higher antibody titers as compared to CSF114(Glc). Finally, the conformational properties of SP077 were studied by NMR spectroscopy and structure calculations. Thus, the immunological activity of SP077 in the recognition of specific autoantibodies in multiple sclerosis patients' sera may be ascribed to both the optimized design of its epitopic region and the superior surface interacting properties of its C-terminal region.

Kallikrein 6 Regulates Early CNS Demyelination in a Viral Model of Multiple Sclerosis

Kallikrein 6 (Klk6) is a secreted serine protease that is elevated in active multiple sclerosis lesions and patient sera. To further evaluate the involvement of Klk6 in chronic progressive demyelinating disease, we determined its expression in the brain and spinal cord of SJL mice infected with Theiler's murine encephalomyelitis virus (TMEV) and assessed the effects of Klk6-neutralizing antibodies on disease progression. Klk6 RNA expression was elevated in the brain and spinal cord by 7 days postinfection (dpi). Thereafter, Klk6 expression persisted primarily in the spinal cord reaching a peak of fivefold over controls at mid-chronic stages (60 dpi-120 dpi). Significant elevations in Klk6 RNA were also induced in splenocytes stimulated with viral capsid proteins in vitro and in activated human acute monocytic leukemia cells. Klk6-neutralizing antibodies reduced TMEV-driven brain and spinal cord pathology and delayed-type hypersensitivity (DTH) responses when examined at early chronic time points (40 dpi). Reductions in spinal cord pathology included a decrease in activated monocytes/microglia and reductions in the loss of myelin basic protein (MBP). By 180 dpi, pathology scores no longer differed between groups. These findings point to regulatory activities for Klk6 in the development and progression of central nervous system (CNS) inflammation and demyelination that can be effectively targeted through the early chronic stages with neutralizing antibody.

The antinuclear antibody assay: developing criteria for reflexive anti-dsDNA antibody testing in a laboratory setting

We examined the relationship between antinuclear antibody (ANA) data and the presence of anti-double stranded DNA antibodies (anti-dsDNA). De-identified demographic, ANA and anti-dsDNA data were available for 30,196 individuals aged ≥ 20 years, whose sera were submitted sequentially to our laboratory. When multiple sera were received for the same subject, data from the earliest sample were used. Anti-dsDNA frequency was stratified by ANA titer and pattern, sample referral source, and by the patient's age, gender, and diagnosis. For sera with ANA titer ≥ 256 and an accompanying diagnosis of systemic lupus erythematosus, anti-dsDNA frequency was 53.7%, 35.3%, and 37.5% for homogeneous, speckled, or multiple ANA patterns, respectively. Among remaining sera with ANA titer ≥ 256, anti-dsDNA frequency was highest for the homogeneous pattern (15.9%). Anti-dsDNA frequency was three-fold higher among sera submitted by rheumatologists compared with other providers. However, its relative distribution by ANA pattern and titer was similar between these groups. Patient age and gender had no significant effect on anti-dsDNA frequency after ANA data were taken into account. ANA pattern and titer, together with the diagnosis submitted with the serum sample, can be used to guide decisions for reflexive anti-dsDNA testing in a clinical laboratory setting.

Angiopoietin-2 Levels Are Associated with Disease Progression in Metastatic Malignant Melanoma

The blood vessel-destabilizing Tie2 ligand angiopoietin-2 (Ang-2) acts in concert with the vascular endothelial growth factor/vascular endothelial growth factor receptor system to control vessel assembly during tumor progression. We hypothesized that circulating soluble Ang-2 (sAng-2) may be involved in melanoma progression. Serum samples (n=98) from melanoma patients (American Joint Committee on Cancer stages I-IV), biopsies of corresponding patients, and human melanoma cell lines were analyzed for expression of Ang-2 and S100beta. Multiple sera of a subcohort of 33 patients were tested during progression from stage III to IV. Small interfering RNA-based loss-of-function experiments were done to assess effects of Ang-2 on melanoma cells. Circulating levels of sAng-2 correlate with tumor progression in melanoma patients (P<0.0001) and patient survival (P=0.007). Analysis of serum samples during the transition from stage III to IV identified an increase of sAng-2 up to 400%. Comparative analyses revealed a 56% superiority of sAng-2 as predictive marker over the established marker S100beta. Immunohistochemistry and reverse transcription-PCR confirmed the prominent expression of Ang-2 by tumor-associated endothelial cells but identified Ang-2 also as a secreted product of melanoma cells themselves. Corresponding cellular experiments revealed that human melanoma-isolated tumor cells were Tie2 positive and that Ang-2 acted as an autocrine regulator of melanoma cell migration and invasion. The experiments establish sAng-2 as a biomarker of melanoma progression and metastasis correlating with tumor load and overall survival. The identification of an autocrine angiopoietin/Tie loop controlling melanoma migration and invasion warrants further functional experiments and validate the angiopoietin/Tie system as a promising therapeutic target for human melanomas.

Failure to confirm HIV infection in two end‐stage HIV/AIDS patients using a popular commercial line immunoassay

Immunoassays using either viral lysate (Western blot) or recombinant/synthetic antigen (immunoblot) for anti-HIV capture are still the preferred method to confirm HIV infection. Two cases of HIV-1-infected patients presented with acquired immunodeficiency syndrome (AIDS)-defining illnesses. Laboratory tests were performed using multiple commercial HIV test kits on multiple sera from both patients over several weeks. Both patients were strongly positive on the anti-HIV/p24 antigen combined screening assay. Yet, HIV-1 infection could not be confirmed using a popular commercial immunoassay. Eventually, HIV infection was confirmed using an alternative commercial Western blot assay as well as an HIV quantitative PCR test. In laboratories without nucleic acid testing (NAT) for HIV, indeterminate results may delay confirmation of HIV infection, if commercial line immunoassays alone are available. Some end-stage HIV/AIDS patients may not produce antibodies to specific HIV antigens and may therefore give indeterminant or negative results on some immunoassays, depending on the type of antigen used. This report highlights the utility of having NAT available when diagnosing difficult cases of HIV infection, especially in light of the recent Centers for Disease Control and Prevention move towards more universal, routine, HIV testing.

Ferrocenyl glycopeptides as electrochemical probes to detect autoantibodies in multiple sclerosis patients' sera

Glycopeptide analogues of CSF114(Glc), modified at N-terminus with new ferrocenyl carboxylic acid and a new ferrocenyl-thiphosphino amino acid, were used to implement a new electrochemical biosensor for autoantibody detection in multiple sclerosis. The ferrocenyl moiety of these "electrochemical probes" did not affect autoantibody recognition both in SP-ELISA and in inhibition experiments. By electrochemical monitoring the interactions of the modified peptides Fc-CSF114(Glc) and 4-FcPhP(S)Abu-CSF114(Glc) with the autoantibodies, we demonstrated that autoantibodies could be detected with a sensitivity comparable to ELISA method. The new electrochemical probes can be proposed to characterize autoantibodies as biomarkers of multiple sclerosis by a simple, rapid, and reproducible cyclic voltammetry-based diagnostic methodology.

Use of Sera from Humans and Dolphins with Lacaziosis and Sera from Experimentally Infected Mice for Western Blot Analyses of Lacazia loboi Antigens

Antibodies in the sera of patients with lacaziosis recognized an approximately 193-kDa antigen and other Lacazia loboi antigens. Paracoccidioides brasiliensis gp43 antigen was detected by all evaluated sera, but they failed to detect a protein with the same molecular mass in L. loboi extracts. This study is the first to examine the humoral response to L. loboi antigens by using multiple host sera.

Association of Elevated Pretransplant sCD30 Levels With Graft Loss in 206 Patients Treated With Modern Immunosuppressive Therapies After Renal Transplantation

Recent reports suggest that high pretransplant serum levels of soluble CD30 (sCD30) are a risk factor for rejections after kidney transplantation. The aim of our study was to elucidate the predictive value of pretransplant sCD30 levels for kidney transplantation outcome in a single-center patient cohort that has been treated with modern immunosuppressive therapies after transplantation. We retrospectively analyzed sCD30 in multiple pretransplant sera from 206 patients, of whom 174 were transplanted with a cadaveric kidney and 32 patients received an allograft from a living donor. Renal function after transplantation was estimated by measuring serum creatinine and by rejection diagnosis. We could demonstrate a statistically significant association between increased pretransplant sCD30 values and graft failures (P=0.005). Receiver operating curve analysis revealed a cutoff value of 124 U/mL pretransplant sCD30. A multivariate analysis confirmed pretransplant sCD30 values >124 U/mL (P=0.011) and rejection episodes (P<0.0001) as independent risk factors for graft loss. Our study revealed a strong correlation between pretransplant sCD30 levels and the incidence of graft failure, but we could not confirm that the development of rejection episodes is correlated with pretransplant sCD30 values.

Combined testing of antibody titer and affinity improves insulin autoantibody measurement: Diabetes Antibody Standardization Program

The aim of the workshop was to assess whether four laboratories could reproducibly measure insulin autoantibody (IAA) affinity in coded sera from non-diabetic relatives of patients with type 1 diabetes, newly diagnosed patients, and healthy blood donors, and whether combining affinity with autoantibody titer could improve concordance and performance of IAA assays. IAA affinity was measured by competitive binding using constant amounts of Tyr 14A [ 125I] human insulin and increasing quantities of unlabeled human insulin. There was high concordance between laboratories in distinguishing high, moderate, and low affinity IAA, although IAA binding to insulin varied with assay format. Multiple islet autoantibody-positive and patient sera were identified by high affinity IAA regardless of laboratory-designated IAA status. Combining affinity and titer significantly improved sensitivity, specificity, and concordance of IAA measurement. This workshop has demonstrated that different laboratories are able to reproduce IAA affinity results and that considering IAA affinity is likely to improve the diagnostic performance of IAA assays.

Conformation−Activity Relationship of Designed Glycopeptides as Synthetic Probes for the Detection of Autoantibodies, Biomarkers of Multiple Sclerosis

Sera from patients suffering from autoimmune disorders often contain multiple types of autoantibodies, some of which can be exclusive of a disease and thus used as biomarkers for diagnosis. Identification of these autoantibodies, as disease biomarkers, should be achieved using native antigens in simple biological assays. However, posttranslational modifications, such as glycosylation, may play a fundamental role for specific autoantibody recognition. In line with these observations, we described synthetic glycopeptides able to detect high autoantibody titers in sera of patients affected by multiple sclerosis, an inflammatory, demyelinating disease of the central nervous system. We describe here the conformation-activity relationship of a focused library of glycopeptides based on structural diversity, with the aim of defining the structural requirements for the interaction of these glycopeptide antigens with specific autoantibodies. The final goal is the optimization of an antigenic probe for multiple sclerosis, to be used in the development of a simple diagnostic test based on an immunoenzymatic assay. The reported results clearly indicate that glycopeptides able to reveal high antibody titers in multiple sclerosis sera are characterized by a type I' beta-turn around the minimal epitope Asn(Glc), which allows an efficient exposure of this moiety to antibodies interactions, in the context of a solid-phase immunoenzymatic assay.

Serum autoantibodies to cell surface determinants in multiple sclerosis: a flow cytometric study.

Multiple sclerosis is thought to be an autoimmune, inflammatory, cell-mediated disease. However, there is evidence suggesting that autoantibodies could play a role in the pathogenesis of multiple sclerosis. Many studies have looked for antibodies to candidate antigens such as myelin basic protein or myelin-oligodendrocyte glycoprotein, with inconclusive results. In order to determine whether antibodies to cell surface determinants on oligodendrocyte or neuronal cells were present in multiple sclerosis, we used flow cytometry to detect antibody binding to intact cultured human cell lines, comparing sera from multiple sclerosis patients with sera from patients with other inflammatory CNS diseases. Sera from healthy individuals were used to determine a normal range. Significant surface binding of IgG or IgM antibodies to oligodendrocyte precursor (OPC)-derived cell lines was seen in 50% of multiple sclerosis sera with no significant difference between secondary progressive (SPMS) and relapsing-remitting (RRMS) subgroups. In contrast, binding to a neuronal cell line, SK-N-SH, was seen with 70% of SPMS sera compared with 25% of RRMS sera (P < 0.001). No significant difference in antibody binding between multiple sclerosis sera and control sera was seen when OPCs were differentiated or when the cells were permeabilized to expose intracellular antigens. Results from all nine patients with 'benign' multiple sclerosis were indistinguishable from controls. This study represents a systematic approach to begin to define new antigenic targets in multiple sclerosis and demonstrates that antibodies to accessible antigens on the cell surface of both OPCs and neurons are present in some patients. The results lend support to the possibility that autoantibody-mediated processes are important in a subgroup of multiple sclerosis patients. Identification of the cell surface determinants to which the antibodies bind may shed light on new targets for therapeutic intervention.

Analysis of Antibody Response to Cryptococcus neoformans in Five Patients with AIDS and Cryptococcosis by Immunoblotting

Objectives: The serological response of five patients with AIDS and cryptococcosis to non capsular antigens from Cryptococcus neoformans var. neoformans has been investigated.Methods:Pressates of different isolates of C. neoformans were used as antigenic preparation for immunoblotting of patient samples.Results: Multiple sera and cerebrospinal fluids sequentially collected from five AIDS patients with cryptococcosis showed a wide heterogeneity in antibody response with bands at 48, 43, 38 and 26 kD being present in all clinical samples of all five patients. The variation in banding patterns of the sequential samples from three patients was correlated with a decrease of the antigen titre and with an amelioration of the cryptococcal infection.Conclusions: We identified antibodies to four immunodominant non-capsular antigens, which might represent major target molecules of the humoral response of patients with cryptococcosis.

Post-obstruction rat sperm autoantigens identified by two-dimensional gel electrophoresis and western blotting

Although antisperm autoantibody responses to obstruction of the male reproductive system have been documented, information on the nature of the cognate sperm autoantigens has been limited. In the present study, the patterns of sperm autoantigens recognized by sera from rats after obstruction of the vas deferens or epididymis were studied by high resolution two-dimensional (2-D) gel electrophoresis and western blotting. Comparisons of patterns of autoantigens stained on 2-D western blots of sera from prepubertal vasectomy, prepubertal epididymal ligation and adult vasectomy groups revealed both similarities and differences. Sera from sham-operated animals showed no detectable reaction or much lighter staining of a small number of spots. Visualization of sperm autoantigens on 2-D western blots supported the hypothesis that there is a relatively small set of sperm proteins that can be regarded as dominant post-obstruction sperm autoantigens because they are recognized by multiple post-obstruction sera. The 2-D analysis revealed previously undetected distinctions in the autoantigens recognized after adult and prepubertal vasectomy, as well as variations with the site of obstruction. These differences in the response may be due in part to changes in antigens of spermatozoa in different parts of the tract and at different ages, as well as variations in exposure of sperm cell proteins to the immune system resulting from the sites of spermatic granulomas. Preparative 2-D gels and western blotting with post-obstruction sera are now being used to identify specific sperm autoantigens by microsequencing of selected proteins.

A critical evaluation of enzyme immunoassays for detection of antinuclear autoantibodies of defined specificities. I. Precision, sensitivity, and specificity.

To determine the performance characteristics of enzyme-based immunoassay (EIA) kits for the detection of antinuclear and other autoantibodies of defined specificities. Nine manufacturers of EIA kits to detect antibodies of defined specificities participated in a study in which they received coded sera from the Centers for Disease Control and Prevention. These coded sera contained different dilutions of antibody of one specificity mixed with sera containing antibodies of other specificities. The manufacturers were asked to use their standard technology to determine antibody content and send the data to a committee of the International Union of Immunological Societies for analysis. The data were analyzed for sensitivity and specificity in the detection of anti-double-stranded DNA (anti-dsDNA), anti-single-stranded DNA, antihistone, anti-Sm, anti-U1 RNP, anti-SSA/Ro, anti-SSB/La, anti-Scl-70 (DNA topoisomerase I), anticentromere, and anti-Jo-1 antibodies. In addition, replicate samples were included in the coded sera to evaluate the precision of each EIA method. Lack of sensitivity and specificity was most evident in the anti-dsDNA and anti-Sm kits, although 2 kits for anti-dsDNA achieved acceptable sensitivity and specificity. Generally, anti-SSA/Ro, anti-SSB/La, anti-Scl-70, anticentromere, and anti-Jo-1 kits performed well. Many false-positive results were obtained with a multiple myeloma serum containing cryoprecipitates, but multiple myeloma sera without cryoprecipitates presented no problem in the EIA system. Precision, based on evaluation of replicate samples, varied from very good to poor. No single manufacturer was clearly superior to others in terms of their products' overall sensitivity, specificity, and precision. Areas that needed improvement were in kits for the detection of antibodies to dsDNA and to Sm antigen. Some EIA kits achieved good sensitivity and specificity. Individual manufacturers were informed of the performance of their respective kits so they could take measures to correct perceived deficiencies and thus improve the reliability of a group of important diagnostic assays used in the evaluation of systemic rheumatic diseases.

With regard to glycohemoglobin measurement: are we sure that high-performance liquid chromatography currently works in the clinical routine?

The clinical usefulness of glycated hemoglobin (HbA1C) depends crucially on the accuracy and precision of its assay. When we compared an immunological bench-top analyzer (DCA 2000, Bayer Diagnostici, Milan) to the high-performance liquid chromatography (HPLC) reference method used in a routine hospital laboratory (Diamat and Fast Diamat, Bio-Rad Lab., Milan) by assaying multiple control sera, we found so many sources of systematic analytical errors in the routine use of HPLC as to compromise between-assay precision. DCA 2000 showed intra- and interassay coefficients of variation (CV) of 1.1% and 2.3% with the normal standard serum, 1.0% and 4.2% with the pathological one; Diamat yielded CVs of 1.3% and 7.0%, 1.3% and 5.7%, respectively. Although the measurement of 161 blood samples showed that Diamat usually overestimated HbA1C (paired t-test, P<0.001), a great variability of Diamat performance became evident when the relationship Diamat vs DCA was evaluated day by day over 17 days of observation (analysis of variance, ANOVA, P<0.001). Intra- and interassay CVs of Fast Diamat initially (new instrument still on approval) were 0.6% and 2.5% (normal standard serum), 0.3% and 1.9% (high standard serum), yet after 6 months of routine laboratory use, they became 3.1% and 3.2%, 1% and 12.3%, respectively. Main sources of error were: inaccurate autodilution, unsuitable parameter settings, disregard of the maintenance schedule. We conclude that the tendency to overlook major critical aspects in the routine use of HPLC is detrimental to the quality of HbA1C determination and implies the loss of HbA1C value in clinical practice. Both carefully supervising laboratory quality and checking the likelihood of the analytical result with the clinical setting appear even more important.