SEARCH · PubMed Health

Results for “ELISA assay variability”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources

PubMed1990

A sensitive antiviral neutralization bioassay for measuring antibodies to interferons.

An improved bioassay for measuring neutralizing antibodies to interferons (IFN) is described. The assay is based upon an objective and precise quantification of the viral cytopathic effect. This effect is measured via the dehydrogenase-system in cells, and quantified spectrophotometrically. Virus-infected cells, in contrast to non-infected cells, possess low enzyme activity resulting in low OD signals. This fall in OD can be prevented by the addition of a small, but fixed amount of IFN before the addition of virus. Anti-IFN sera will neutralize the protective effect of IFN. This effect can be quantified by measurement of the reduction in the OD signals. Antibodies to recombinant IFN were found to cross-react with human leukocyte IFN although to a ten-fold lower degree. The assay requires no expensive reagents, it is performed in 96-well microtrays and the results can be measured in an ordinary ELISA scanner. The assay is highly reproducible, yielding inter- and intra-assay variability of less than 10%. The sensitivity is much higher than that reported previously for the CPE technique and that of ELISA techniques.

Animals↗

PubMed1995

Serologic responses of dogs naturally exposed to or vaccinated against Borrelia burgdorferi infection.

OBJECTIVE: To characterize the serologic responses of dogs naturally exposed to or vaccinated against Borrelia burgdorferi and to assess responses at intervals after antibiotic treatment. DESIGN: Prospective, controlled clinical trial. ANIMALS: 19 dogs of various breeds and ages with narrowly defined clinical criteria of limb/joint borreliosis and 10 control dogs of equivalent age were used to determine serologic responses following natural exposure to the organism. Eight seronegative dogs were used to determine serologic responses following vaccination. PROCEDURE: Serologic responses to B burgdorferi and recombinant outer surface protein (Osp)A, flagellin, and P39 were assessed by means of ELISA and western immunoblot. Passive protective activity was assessed by use of a mouse protection assay. RESULTS: Naturally exposed dogs were seropositive, but had variable ELISA titers and immunoblot profiles. Immunoblot analysis did reveal consistent reactions to flagellin, P39, and a 22 kd protein, but not to OspA. Antibody responses did not change appreciably up to 13 weeks after antibiotic treatment. Vaccinated dogs had strong reactions to OspA and OspB, but not to P39. CLINICAL IMPLICATIONS: Dogs with clinical borreliosis are seropositive and remain seropositive after antibiotic treatment, emphasizing that serologic testing is not a useful means of measuring clinical response. Serologic responses of infected dogs can be discriminated from those of vaccinated dogs by means of immunoblot analysis, and recombinant P39 is a potentially useful antigen for that purpose.

Animals↗

PubMed2003

Monoclonal antibodies to human cartilage oligomeric matrix protein: epitope mapping and characterization of sandwich ELISA.

BACKGROUND: Cartilage oligomeric matrix protein/thrombospondin 5 (COMP/TSP 5) is one of the most promising serologic markers with regard to an ability to prognose development of osteoarthritis (OA). Our aim was to map the epitopes of three monoclonal antibodies (mAb) to COMP and to develop and characterize a sandwich enzyme-linked immunosorbent assay (ELISA) for measuring COMP levels in human body fluids. METHODS: COMP was digested with trypsin and the NH(2)-terminal sequence of the fragments recognized by each of the mAbs was determined. Steric competition among the mAbs was tested with an antibody capture assay. A sandwich ELISA was developed using unlabeled mAb 16-F12 as a capture antibody, and mAb 17-C10 labeled with biotin as the second antibody. RESULTS: Epitopes of the three mAbs were mapped to three different domains within the COMP subunit (16-F12, NH(2)-terminal domain; 17-C10, EGF-like domain; 12-C4, COOH-terminal domain). These epitopes did not overlap. mAbs 17-C10 and 12-C4 yielded similar serum COMP results when used as the secondary antibodies. Serum COMP levels measured with the new sandwich ELISA using mAbs 16-F12 and 17-C10 correlated strongly with results based on an inhibition ELISA with mAb 17-C10 alone (r(2) = 0.836; P < 0.0001). We characterized the new sandwich ELISA with regards to inter- and intra-assay variability, the range of COMP levels that can be expected in human synovial fluids (SF) and sera (controls and OA and rheumatoid arthritis (RA) patients), and the day-to-day and diurnal variability of COMP levels in sera. CONCLUSIONS: We have developed and characterized a sandwich ELISA for COMP that is sensitive and yields highly reproducible COMP results upon analysis of human sera and synovial fluids.

Antibodies, Monoclonal↗

PubMed2005

Comparison of milk-ELISA and serum-ELISA for the diagnosis of Brucella melitensis infection in sheep.

Milk and blood samples from 704 lactating ewes were examined for the diagnosis of Brucella melitensis infection by milk-ELISA, serum-ELISA, RBPT, SAT and culture of milk. Of these ewes, 209 were from brucellosis free sheep flock, 443 from brucellosis infected sheep flock and 52 were from private sheep flocks of which status for brucellosis was not known. All the 209 ewes belonging to uninfected sheep flock were found negative in all the tests and of the remaining 495 ewes 105 were positive in serum-ELISA, 103 in milk-ELISA, 92 in RBPT, 85 in SAT, and B. melitensis biovar-1 was isolated from the milk of 29 ewes. Of the 105 serum-ELISA positive ewes, 99 were positive and 6 were negative in milk-ELISA, whereas of the 103 milk-ELISA positive ewes, 4 were negative in serum-ELISA. All together, 99 ewes were positive and 386 were negative in both the assays while 10 ewes yielded variable results. The specificity of milk-ELISA in brucellosis free flock was 100% and sensitivity and positive predictive value were 96.11% and 94.28%, respectively, in infected flocks. The Brucella antibody levels in milk and serum samples as determined by milk-ELISA and serum-ELISA were correlated significantly. The milk-ELISA for brucellosis appears to be an attractive alternative of serum-ELISA particularly in the lactating ewes.

Agglutination Tests↗

PubMed2004

Production of a functional chicken single-chain variable fragment antibody derived from caecal tonsils B lymphocytes against macrogamonts of Eimeria tenella.

Avian coccidiosis is due to a protozoan intracellular parasite belonging to the genus Eimeria which multiplies in the intestine of the host. In order to identify Eimeria antigens which reflect the natural avian humoral immune response, chicken hybridomas were produced by fusion of myeloma MuH1 with B lymphocytes from Eimeria tenella infected chicken. B lymphocytes used for fusions were isolated from tonsils at the basis of caeca where the parasite develops. One of the clones (G1F5) recognised oocyst antigens and the macrogamont stage of the parasite in ELISA and immunofluorescence assay. A single-chain variable fragment (scFv) antibody was cloned from the light chain variant region (VL) and heavy chain variant region (VH) genes of the hybridoma. This recombinant antibody (scFv G1F5) exhibited antigen binding specificity to oocysts and macrogamonts of E. tenella equivalent to the mAb produced by the clone G1F5. Nucleotide sequence analysis of VL genes from scFv G1F5 compared to the germ-line revealed vestiges of gene conversion. scFv derived from chicken B lymphocytes isolated from the gut-associated lymphoid tissue following experimental infection can reveal specific antigens recognised by the avian immune response.

Animals↗

PubMed2004

Osteopontin is an adhesive factor for myeloma cells and is found in increased levels in plasma from patients with multiple myeloma.

BACKGROUND AND OBJECTIVES: Osteopontin (OPN) is a non-collagenous matrix protein produced by various cells including osteoblasts, osteoclasts and several types of tumor cells. It is involved in a number of physiologic and pathologic events including adhesion, angiogenesis, apoptosis, inflammation, wound healing and tumor metastasis. We wanted to investigate the potential role of OPN in multiple myeloma. DESIGN AND METHODS: Myeloma cells and stromal cells from myeloma patients were investigated as potential OPN-producers. Furthermore, OPN was tested in proliferation, migration and adhesion assays with myeloma cells. Serum and plasma OPN in myeloma patients were measured by enzyme-linked immunosorbent assay (ELISA). OPN levels were correlated to disease variables at diagnosis and to disease outcome. RESULTS: Myeloma cells produce OPN, and stromal cells from myeloma patients express higher levels of OPN than stromal cells from healthy controls. The myeloma cell lines ANBL-6 and INA-6 adhered to OPN. NOD/SCID mice inoculated with OPN-producing ANBL-6 cells had elevated levels of murine OPN in serum, whereas human OPN was not detectable. Plasma and serum levels of OPN were significantly higher in myeloma patients than in healthy individuals. Interpretation and Conclusions. Myeloma cell lines adhere to OPN, indicating that elevated stromal expression of OPN may be one of the factors responsible for the retention of myeloma cells in the bone marrow. The elevated plasma OPN levels in myeloma patients could be due to both production of OPN by the tumor cells and tumor-induced production of OPN by non-tumor cells.

Adult↗

PubMed1992

Elementary school students' performance with two ELISA test systems.

OBJECTIVE: To examine analytic performance by previously untrained and inexperienced subjects using enzyme-linked immunosorbent assay (ELISA) tests developed for decentralized laboratories. Performance variability between tests assigned to the "simple" and "moderately complex" Health Care Financing Administration laboratory levels was evaluated. DESIGN: A nonrandomized trial of the Surecell Strep-A chorionic gonadotropin ELISA tests. Each subject processed nine unknown specimens (three negative, three weakly positive, and three strongly positive) for each ELISA test. Subjects were blinded to expected test results. SETTING: An elementary school. SUBJECTS: A convenience sample of 52 students enrolled in the sixth and seventh grades. This age group was chosen because of their ability to generally comprehend instructions and remain attentive to the testing task. INTERVENTIONS: Subjects were either self-trained by reading package insert directions or trained by a manufacturer's sales representative. MAIN OUTCOME MEASURES: Performance was measured as the percentage of correct test results for the unknown specimens. The sensitivity and specificity for each test by operator group were calculated. RESULTS: Subjects demonstrated an overall sensitivity of 97.1% and specificity of 94.7% for human chorionic gonadotropin unknown specimens and a 95.9% sensitivity and 96.8% specificity for group A streptococcus unknown specimens. No significant differences between the self-trained group and the representative-trained group were observed for either group A streptococcus or human chorionic gonadotropin tests. Performance was so high with the first specimen that improvement over time (ie, a "learning curve") could not be demonstrated. CONCLUSION: These ELISA test systems are able to achieve high levels of performance by subjects with no formal laboratory background, no previous method specific experience, and limited self-training.

Adolescent↗

PubMed1991

The repertoire diversity and magnitude of antibody responses to bacterial antigens in aged mice: I. Age-associated changes in antibody responses differ according to the mouse strain.

Aging influences the host immune responses in various ways. In aging mice we have studied the antibody responses to two unrelated bacterial antigens. Streptococcus pneumoniae R36a vaccine (Pn) and TNP coupled to Brucella abortus (TNP-BA). Aged animals (20-24 months old) of the C57BL/6 strain had markedly reduced numbers of IgM antibody plaque-forming cells (PFC) to Pn as compared to young/adult mice (2-3 months old). In contrast, the anti-Pn IgM PFC responses of aged BALB/c mice were consistently higher than they were in the young/adult mice. The increased anti-Pn responses were not due to a nonspecific immunostimulation, because the responses of aged BALB/c mice to TNP-BA were lower as compared to the adults. However, the aged BALB/c mice responded relatively poorly to Pn challenge, and their IgG responses (as determined by ELISA plaque assay) demonstrated a very high individual variability. The clonotypic diversity of anti-Pn response in young BALB/c and C57BL/6 is limited, such that the majority of PFC produce antibody that express all idiotopes (Id) of the T15 immunoglobulin encoded in the VH-S107/Vk22 genes. In contrast, the PFC from aged mice are diverse, expressing incomplete T15 Id or none at all, suggesting that the antibodies are encoded by altered T15 genes and by different, non-T15 genes. Our data demonstrate that the age-related changes in the magnitude of antibody response to certain antigens are influenced by the host genetic make-up, and that the changes in magnitude and diversity of antibody response may be unrelated to each other.

Aging↗

PubMed2002

Enhanced enzyme-linked immunosorbent assay for detection of antibodies to virus-like particles of human papillomavirus.

Measurement of antibodies to human papillomavirus (HPV) is complicated by many factors. Although enzyme-linked immunosorbent assays (ELISAs) that use virus-like particles (VLPs) have proved useful, the assays have, in general, had moderate sensitivities and low signal-to-noise ratios. To enhance the performance of the assay, a systematic investigation was undertaken to examine key variables used in ELISAs for the detection of antibodies to VLPs of HPV. Incorporation of two vinyl polymers, polyvinyl alcohol (molecular weight, 50,000) (PVA-50) and polyvinylpyrrolidone (molecular weight, 360,000) (PVP-360), was found to increase the sensitivity as well as the specificity of the assay for the detection of antibodies to VLPs of HPV. In particular, the addition of PVA-50 to the blocking solution reduced the amount of nonspecific binding of antibodies to VLPs and the microplate surface, whereas the addition of PVP-360 increased the sensitivity of antibody detection. The new ELISA demonstrated increased sensitivity and specificity for the detection of cervical HPV type 16 infection compared to those of a prototype assay with coded clinical serum samples from women with known cervicovaginal HPV infection status. It is anticipated that the enhanced ELISA conditions will have wide application to a large number of clinical diagnostic assays.

Animals↗

PubMed1997

Standardization of an opsonophagocytic assay for the measurement of functional antibody activity against Streptococcus pneumoniae using differentiated HL-60 cells.

Host protection against pneumococcal disease i primarily mediated by phagocytosis. We developed and standardized an opsonophagocytic assay using HL-60 cells (human promyelocytic leukemia cells). Fifty-five serum samples were analyzed for the presence of functional antibody against seven pneumococcal serogroups or serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) by using differentiated HL-60 cells (granulocytes) and peripheral blood leukocytes (PBLs). Six of the 55 serum samples were from unvaccinated adult volunteers, 31 serum samples were from adults who received one dose of the 14-valent or the 23-valent polysaccharide vaccine, and 18 serum samples were from 16-month-old infants who received four doses of an investigational 7-valent polysaccharide-protein conjugate vaccine. The results of an opsonophagocytic assay with HL-60 cells correlated highly with those of an assay with PBLs as effector cells (median r for seven serotypes = 0.87: P < 0.01). Opsonophagocytic titers were compared with the immunoglobulin G antibody concentrations determined by enzyme-linked immunosorbent assay (ELISA). The r values for serogroups or serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F were 0.61, 0.60, 0.67 0.90, 0.61, 0.39, and 0.57, respectively, when HL-60 cells were used as effector cells and 0.56, 0.47, 0.61, 0.90, 0.71, 0.31, and 0.62, respectively, when PBLs were used. The assay requires small amounts of serum (40 microliters per serotype), making this test suitable for assaying infant sera. Culturable cells aid in assay standardization and likely reduce donor-to-donor variability. This standardized assay, in combination with the standardized ELISA, can be used to evaluate current and developing pneumococcal vaccines, in which functional opsonophagocytic antibody activity may correlate with protection against pneumococcal disease.

Adult↗

PubMed1996

Absorption and imagery locate immune responses in the body.

Imagery instructions specifying mucosal immunity should alter mucosal immunoglobulin A (m-IgA) levels in high absorbers, whose intent concentration evokes intense physiological responses. After screening for health status, 121 high or low absorbers were randomly assigned to either Relaxation Alone (R), Relaxation with Mucosal Immune Imagery (RI), or Vigilance Task control (VT). Before and after one 60-min intervention, subjects reported theory-relevant psychological variables and provided 5 ml whole saliva, which was immediately frozen and assayed later en masse with enzyme-linked immunoabsorbence (ELISA). MANOVA analysis of psychological variables replicated past research. ANOVA on residualized m-IgA found Time x Absorption interaction and Condition main effects. High more than low absorbers responded to relaxation with mucosal immune imagery by producing higher m-IgA. High absorbers appear able to locate where their immune systems will respond. Individual differences like absorption level need to be emphasized in diagnosis and treatment responsiveness.

Absorption↗

PubMedDate not supplied

Antigenic proteins in latex glove extracts: sources of variability.

Antigenic protein levels in commercially available latex medical gloves were studied. For comparison, the gloves were divided into four main groups; powdered examination, powder-free examination, powdered surgical, and powder-free surgical. Residual protein levels of 91 different glove brands were determined using the LEAP (latex ELISA for antigenic proteins) assay and found to be extremely variable. The possible sources of variability were investigated. Lot-to-lot variability was determined by testing multiple lots of five different brands of surgical gloves. The authors also determined glove-to-glove variability, variability within an individual glove, and test-method variability. It was observed that lot-to-lot variability (25-61% relative standard deviation--RSD) and glove-to-glove variability (51% RSD) were of similar magnitude and accounted for most of the variability found within a given brand of gloves. However, the greatest source of variability identified was brand-to-brand variability (143-283% RSD).

Antigens↗

PubMed1994

Use of combined Shewhart-CUSUM control charts in internal quality control of enzyme-linked immunosorbent assays for the typing of foot and mouth disease virus antigen.

An enzyme-linked immunosorbent assay (ELISA) for the typing of foot and mouth disease virus (FMDV) antigen was employed for the routine laboratory diagnosis of FMD at a regional veterinary laboratory in northern Thailand. An objective procedure was developed to monitor the test performance of the ELISA, using absolute test control limits in a Shewhart-CUSUM (cumulative sum) control chart method. The procedure detected significant data trends and 'beyond control limit' situations for each antigen typing system (types O, A and Asia 1), using an assay variable (gamma i). Retrospective analysis using Shewhart-CUSUM control charts of data from 42 ELISAs demonstrated that control limits were exceeded in two assays for FMDV type A. The Shewhart-CUSUM control chart is a simple and reliable internal quality control method for the detection of significant random and systematic variation in assays.

Animals↗

PubMedDate not supplied

Major allergen measurements: sources of variability, validation, quality assurance, and utility for laboratories, manufacturers, and clinics.

The isolation and characterization of prominent allergenic proteins or glycoproteins is an important step in the development of allergenic extracts exhibiting improved definition, consistency, and clinical utility. Quantitative analyses specific for major allergenic components currently are being performed in numerous corporate and academic laboratories but have not been validated within or across laboratories in a systematic manner. In our laboratory, validation of double-bind (sandwich) ELISA assays for a diverse group of major allergens or extract components revealed a number of critical assay variables and reagent incubation conditions that directly influenced the precision, accuracy, specificity, and robustness of these tests. Data from ELISA methods for six allergens (Dermatophagoides farinae Der f 1, Alternaria Alt a 1, dog albumin, dog Can f 1, fire ant Sol i 3, and yellow jacket venom Ves 5) showed that up to twofold differences in results were observed when analysts or microplates were varied. Analyses of dog allergens using multiple reagents and concentrations indicated that twofold variations in results also can be produced by distinct combinations of materials or incubations from different assay steps. Data from Can f 1 and egg white analyses produced up to fivefold differences in antigen concentrations based on changes in the capture antibody source (mouse monoclonal versus rabbit polyclonal) or storage buffer. These results suggest that differences in major allergen concentrations reported by different testing laboratories may be related to assay differences as well as extract variations and raise questions as to the accuracy of major allergen concentrations and therapeutic dose recommendations reported at regional and national allergy meetings. Validated double-bind ELISA methods may be well suited for consistency monitoring and standardization of extracts provided that reference materials, reagent qualifications, and interlaboratory comparability are defined precisely.

Allergens↗

PubMed2002

Seroprevalence of toxoplasma infection among primigravid women attending antenatal clinic at a secondary level hospital in North India.

A study was carried out among primigravid women attending a secondary level hospital in a district of North India. The objective of the study was to determine seroprevalence rate of Toxoplasma gondii infection using enzyme-linked immunosorbent assay (ELISA) test. Associations between toxoplasma seropositivity and selected variables (socio-demographic and biologically plausible variables) were also studied. Five hundred three women were enrolled from the antenatal clinic between August, 1996 and September, 1997. Of these, 210 women (41.75%) were seropositive for Toxoplasma gondii infection. These results indicate that a large number of the study subjects were vulnerable to toxoplasma infection. If these infections had occurred during the pregnancy, their foetuses would have been at high risk of infection. There was no statistically significant association between toxoplasma seropositivity and the variables studied except, in the case of type of meat usually consumed. There is a need to provide health education to pregnant women in order to prevent primary toxoplasma infection during pregnancy.

Adolescent↗

PubMed2006

Use of age and milk production data to improve the ability of enzyme-linked immunosorbent assay test results to predict Mycobacterium avium ssp. paratuberculosis fecal culture status.

Cows from 2 California dairies were tested for paratuberculosis at the end of lactation by using fecal culture and a commercially available serum enzyme-linked immunosorbent assay (ELISA) test kit. Individual cow characteristics and production variables were evaluated along with ELISA testing results as predictors of fecal culture status. In multivariable logistic regression analysis, age and a herd-standardized version of 305-day mature equivalent (305 ME) milk production were significant predictors of fecal culture status after adjusting for herd, quarter of the study year, and ELISA sample-to-positive (S/P) ratio. The area under a nonparametric receiver operating characteristic curve was significantly greater for a multivariable model that included age and the level of milk production when compared with a model without these covariates. In conclusion, consideration of cow-level covariates was useful as an aid in predicting Mycobacterium avium ssp. paratuberculosis (MAP) fecal culture status. For a given ELISA S/P ratio, older cows and those with lower 305 ME milk production relative to other cows in the herd were significantly more likely to be shedding MAP in their feces at the end of lactation.

Age Factors↗

PubMed1997

Amphotericin B enzyme-linked immunoassay for clinical use: comparison with bioassay and HPLC.

OBJECTIVE: To evaluate a new enzyme-linked immunosorbent assay (ELISA) for amphotericin B in serum samples. Results are compared with those obtained by HPLC and bioassay. DESIGN: Comparison of results obtained by ELISA, HPLC, and bioassay. METHODS: We developed a new ELISA using a polyclonal rabbit antibody to measure serum amphotericin B concentrations. Blinded samples of amphotericin B in concentrations of 0.15-78 micrograms/mL were prepared in human serum and assayed simultaneously by the ELISA, HPLC, and bioassay. The results of each assay were derived from standard curves and evaluated by using the Table Curve 2D computer program. These data were compared by using correlation analysis with evaluation of Pearson's correlation coefficient by Student's t-test. RESULTS: ELISA and bioassay compared favorably at amphotericin B concentrations of 0.3-20 micrograms/mL with a correlation coefficient of r = 0.993, while ELISA and HPLC compared with a correlation coefficient of r = 0.944. The average coefficient of variation over the range 0.3-20.0 micrograms/mL was 28% +/- 7% for HPLC, 26% +/- 9% for ELISA, and 13% +/- 4% for bioassay. Comparison of all three assays revealed the highest correlation with the ELISA assay (r = 0.998) for the range of concentrations (0.3-20 micrograms/mL) routinely achieved. Samples containing concentrations in excess of 20 micrograms/mL could be diluted. Desiccation for concentrations less than 0.3 microgram/mL was not tested. CONCLUSION: The determination of serum amphotericin B concentrations by ELISA gave results similar to those obtained by a bioassay and HPLC technique. Although variability appears greater with ELISA, the ease of performing yjis assay expedites the evaluation of amphotericin B concentrations from lipid formulations without interference from coadministered antibacterials of azole antifungals.

Amphotericin B↗

PubMed2000

Western blotting is useful in the salivary diagnosis of Helicobacter pylori infection.

BACKGROUND: The salivary diagnosis of Helicobacter pylori infection offers attractive possibilities for the epidemiological study of infection in children. Salivary enzyme linked immunosorbent assay (ELISA) is less reliable then serum ELISA, owing to variable transudation of immunoglobulin. In addition, children are more difficult to study because of lower specific serum antibody concentrations to H pylori. The performance of salivary western blotting in comparison with serum western blotting and serum ELISA was investigated in school children. SUBJECTS AND METHODS: Paired serum and saliva specimens were obtained from 669 [corrected] school children aged 9-11 in 10 British towns. All saliva and serum specimens were first analysed by ELISA; subsequently, western blotting of both specimens was performed on 31 and 34 specimens, respectively, to establish the criteria for positivity for western blotting. The remaining 121 specimens were then tested blindly and saliva was compared with the serum. RESULTS: The sensitivity and specificity of salivary ELISA in the 669 [corrected] specimens was 32 of 50 (64%) and 530 of 619 (86%) [corrected], respectively, when compared with serum ELISA. The western blotting validation was performed on 28 subjects with positive serum and positive salivary ELISA, 28 saliva positives with negative serum, 16 saliva negatives with positive serum, and 50 doubly negative subjects. Compared with serum western blots, the sensitivity and specificity of salivary western blots was 38 of 47 (81%) and 68 of 75 (91%), respectively. Using serum ELISA as the gold standard, the sensitivity and specificity were 32 of 44 (73%) and 72 of 78 (92%), respectively, the specificity being significantly higher than salivary ELISA (p < 0.001). CONCLUSION: Salivary western blotting for IgG is useful in the diagnosis of H pylori infection and is superior to ELISA. It also permits the identification of pathogenic strains.

Blotting, Western↗