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PubMed2004

[Latex agglutination system for the rapid diagnosis of leptospirosis in Cuba].

OBJECTIVES: To assess the sensitivity, specificity, reproducibility, and stability of five latex agglutination systems for detecting antibodies against leptospira in human and animal sera, by using the Leptospira serotypes that are most widely prevalent in Cuba. METHODS: We performed an analytic and descriptive study with 706 human sera (65 tested positive for antibodies against leptospira with microagglutination (MAT) and hemagglutination (HA) techniques; 156 sera that tested negative with MAT and HA); 485 sera from 424 patients who had clinical or epidemiologic signs of leptospirosis; and 29 animal sera (16 from equines, 6 from bovines, 5 from porcines, 1 from a canine, and 1 from an ovine). All of the samples were tested with five latex conjugates made from whole cells of Leptospira interrogans, specifically the four serogroups that circulated most widely in Cuba from 2002 to 2004. The cells obtained from cultured cell lines yielded four specific conjugates (latex-canicola, latex-icterohemorrhagiae, latexpomona, and latex-sejroe), as well as one latex conjugate made from a combination of all four serogroups in equal quantities (latex-pool). In addition, samples were tested with the commercial latex agglutination Lepto Tek Tri Dot (bioMeriuex, France) kit. The stability and reproducibility of the latex conjugates were assessed through monthly controls over a period of 6 months with positive and negative sera. RESULTS: Of the systems that were assessed, the best combination of sensitivity and specificity was obtained with the latex-Pool conjugate (93,8% and 90,4%, respectively). The best combination of positive and negative predictive values was seen with the latex-Sejroe conjugate (90,9% and 95,8%), respectively), followed by the latex-Pool conjugate (94.2% and 96.6%, respectively). The positive and negative predictive values of the Lepto Tek Dri Dot commercial system were 78.5% and 88.4%, respectively. Among the 137 patient samples that tested positive for one of the serotypes when MAT was used, latex conjugates succeeded in correctly identifying 107 (78.1%), whereas the latex-Pool conjugate detected 116 (84.7%) positive sera. When animal sera were tested, the latex-Pool conjugate detected the greatest number of positive serum samples and showed the greatest concordance with MAT (93.1%). The conjugates studied showed good stability and reproducibility. CONCLUSIONS: Latex conjugates made from whole cells of the most widely circulating leptospira in Cuba showed a degree of concordance with MAT that was similar to or better than that seen with the Lepto Tek Dri Dot commercial system, both in human and animal sera. We recommend more widespread use of the latex-Pool conjugate in Cuba in the initial screening for antibodies against leptospira.

Animals↗
PubMed2006

Development of a specific latex agglutination test based on a recombinant hemagglutinin protein to detect antibodies to H5 avian influenza viruses.

A latex agglutination test (LAT) was developed for rapid detection of antibodies to H5 avian influenza viruses (AIVs). The hemagglutinin protein of H5 AIV was covalently linked to carboxylated latex by ethyl-dimethyl-amino-propyl carbodiimide to prepare the sensitized latex beads. The LAT was evaluated with the hemagglutination inhibition (HI) assay as the reference test. The H5-LAT showed a sensitivity of 87.0% and specificity of 88.9% in detecting 126 serum samples from experimentally infected chickens and a sensitivity of 82.5% and specificity of 86% in detecting 587 field chicken serum samples from mostly vaccinated chickens. The agreement ratio between H5-LAT and HI was found to be 87.3% and 83.1% for the two groups of samples, respectively. Difficulty with background agglutination in stored chicken sera was overcome by serum pretreatment with either dried chicken liver powder or dilution buffer containing detergent Tween-20. The H5-LAT has advantages over a previously reported whole-virus LAT in terms of biosafety in preparation, chemical stability, and higher specificity. It is a rapid and simple test suitable for field monitoring of antibodies to H5-type AIV.

Animals↗
PubMed2004

Prevalence of agglutinating antibodies to Sarcocystis neurona in raccoons (Procyon lotor) from an urban area of Virginia.

Equine protozoal myeloencephalitis is the most important protozoan disease of horses in North America and is usually caused by Sarcocystis neurona. Natural and experimentally induced cases of encephalitis caused by S. neurona have been reported in raccoons (Procyon lotor) and raccoons are an intermediate host for this parasite. A 3-yr-long serological survey was conducted to determine the prevalence of agglutinating antibodies to S. neurona in raccoons collected from Fairfax County, Virginia, a suburban-urban area outside Washington, D.C. Samples from 469 raccoons were examined, and agglutinating antibodies (> or = 1:50 dilution) were found in 433 (92.3%) of the raccoons. This study indicates that exposure to S. neurona is high in this metropolitan area.

Animals↗
PubMed1997

Agglutination-inhibition assay for the detection of recombinant proteins tagged with peptide epitopes.

We have demonstrated that the expression of recombinant proteins labeled with an immunoreactive epitope can be rapidly assessed and quantitated using a modified haemagglutination inhibition assay in enzyme-linked immunosorbent assay (ELISA) trays. The agglutination of erythrocytes from a droplet of whole blood provided a simple visual assay. The additional reagents required for the assay were a recombinant anti-human erythrocyte Fab fragment fused to a peptide epitope and a bivalent antibody with specificity to the same epitope. In this report, we found that a convenient and sensitive epitope was the octapeptide FLAG in conjunction with the M2 anti-FLAG antibody, which had affinity to FLAG incorporated either at the C-terminus or N-terminus of the recombinant protein. The agglutination-inhibition (AI) assay was configured to detect as little as 1 mg/L of soluble recombinant protein in a 30-min assay. Since the AI assay was substantially more rapid and convenient than dot-blot or Western blot analyses, our laboratory now uses this method routinely for the assay of FLAG-labeled recombinant products following protein expression and subsequent small- and large-scale purification procedures.

Alkaline Phosphatase↗
PubMed2001

Measurement of serum amyloid A in the neonatal foal using a latex agglutination immunoturbidimetric assay: determination of the normal range, variation with age and response to disease.

This paper describes the use of a latex agglutination assay to measure serum amyloid A (SAA) in the neonatal foal. The normal range and response to clinical disease was determined. This retrospective study evaluated SAA concentrations over the first 3 days postpartum of 226 Thoroughbred foals judged to be clinically healthy. The normal range for each day was determined; levels were found to be significantly highest on Day 2 (Day 1 vs. Day 2 P<0.0001). The 95th percentile for Days 1-3 was 27.1 mg/l. Clinical records of 133 foals, presented as first or second opinion cases, were evaluated. Foals were divided into 4 groups; septicaemia (S), focal infection (FI), failure of passive transfer (FPT) and noninfectious disease (NI). There was a statistically significant difference (P<0.0001) between SAA concentrations of control foals compared to Groups S and FI. There was no statistically significant difference between controls and Groups FPT and NI. When Group NI was compared to Groups S and FI, there was a statistically significant difference (P<0.0001). The authors suggest that SAA determined by this latex agglutination assay might be a helpful aid in the diagnosis of septicaemia and focal infection in neonatal foals; levels >100 mg/l are highly suggestive of infection in young foals.

Age Factors↗
PubMed1985

Ristocetin-induced platelet agglutination in four Chinese patients with Glanzmann's thrombasthenia.

We studied the degree of Ristocetin-induced platelet agglutination in 4 Chinese patients with Glanzmann's thrombasthenia. At Ristocetin concentrations of 1.2-2.0 mg/ml (final concentration) variable, abnormal responses were observed. The most notable feature in 3 of 4 patients studied was the phenomenon of dose dependent, cyclic platelet agglutination-disagglutination. However, this phenomenon could be reproduced in only one of the 2 patients who were investigated on 2 separate occasions. Variable, but often characteristic responses of thrombasthenic platelets to different concentrations of Ristocetin are a useful additional diagnostic marker for this disease.

Blood Platelet Disorders↗
PubMedDate not supplied

Implication of sperm head agglutination induced by a V3 peptide (fragment 307-330, HIV-1 envelope protein gp120) solution.

Human semen is the main vehicle for the transmission of human immunodeficiency virus (HIV); therefore, the interaction of HIV with the sperm is worthy of study. The motile sperm head fixation method was used as an in vitro model system to demonstrate the interaction of sperm with the peptide of HIV envelope protein. A micropipette loaded with semen was put into phosphate-buffered saline (PBS) containing V3 peptide (HIV-1IIIB envelope protein, fragment 307-330) or C2 peptide (HIV-1IIIB envelope protein, fragment 254-274). The V3 peptide caused a significant number of head-to-head binding sperm while the C2 peptide did not. This V3 peptide carries a high positive charge, which may overcome the electrostatic resistance on the cell to bring the sperm together. An HIV-CD4+ cell attachment inhibitor, dextran sulfate (DS, molecular weight about 5000), enhanced the sperm head agglutination induced by the V3 peptide. DS is presumed able to bind with specific sites near the V3 domain of gp120 to induce conformational change so as to prevent the binding of anti-V3 monoclonal antibodies or CD4+ cells to the V3 domain. This study suggests that DS interacts directly with the V3 peptide to enhance the sperm head agglutination.

Amino Acid Sequence↗
PubMed1984

Dynamic evaluation of aggregation and agglutination of red blood cells.

Viscoelastic evaluation of aggregation and agglutination of red blood cells was attempted. A concentric double cylinder viscoelastometer was used for determining the dynamic rigidity modulus and loss modulus of blood sample. The dynamic rigidity modulus of horse blood were measured over a wide range of hematocrit. The relation between the viscoelastic behavior and the erythrocyte sedimentation was examined. The change in the amount of surface charge of enzyme treated red blood cells was qualitatively estimated from the measurements of dynamic viscoelasticity of red blood cells suspension with added poly-L-lysine. The dynamic rigidity modulus of red blood cells agglutinated by adding lectin (concanavalin A) were also measured.

Animals↗
PubMedDate not supplied

Agglutination-induced erythrocyte deformation by two blood group A-specific lectins: studies by light and electron microscopy.

The adhesive energy in lectin-induced agglutination can be assessed by the deformation of erythrocytes in aggregates. Helix pomatia (HPA) and Dolichos biflorus (DBA) specifically agglutinated blood group A erythrocytes and induced a change in curvatures of cells at the end of the aggregates. The curvatures changed from concavity to convexity with increasing lectin concentrations. HPA-induced aggregates achieved the theoretical maximal end cell curvature of 0.27 microns-1 at 2-3 micrograms/ml; DBA-induced aggregates approached 0.23 microns-1, requiring 400 micrograms/ml. At any given lectin concentration, HPA showed greater surface binding, caused higher cell curvatures, induced larger aggregate size, and had greater adhesive energies, as compared to DBA. HPA and DBA are globular proteins with a diameter of approximately 5.5 nm and approximately 6.1 nm, respectively, as revealed by the negative staining electron microscopy. The former induced uniform intercellular spacing (approximately 15 nm), whereas the latter induced both smooth (approximately 20 nm) and ruffled spacings. The uniform intercellular spacing was not a function of lectin concentrations. Microscopic studies of erythrocyte deformation provided morphological correlates of biophysical findings of differential adhesive energies induced by these two blood group A-specific lectins.

ABO Blood-Group System↗
PubMed2004

Comparison of dio-bacit, bacitracin-trimethoprim/ sulphamethoxazole and latex agglutination in the diagnosis of Group A beta-hemolytic streptococci.

Not only is Group A beta-hemolytic Streptococcus (GAS) the most frequent cause of bacterial pharyngitis, it is also the culprit in various skin and systemic infections, acute rheumatic fever, post streptococcal glomerulonephritis, and other disorders and complications. A new, ready-to-use media, Dio-Bacit, in a two section plate containing 5% sheep blood agar on one side and sheep blood agar with bacitracin (2 microg/ml) on the other was compared for its efficiency in identifying GAS with bacitracin and bacitracin + sulphamethaxazole / trimethoprim disk tests applied after isolation of beta-hemolytic colonies. We also used the latex-agglutination test as the gold standard method for differentiating GAS from streptococci belonging to other groups. Compared with the latex-agglutination test, we found the sensitivity and specificity of the Dio-Bacit method to be 92.0% and 96.9%, respectively. Dio-Bacit plates provide an easy and very useful way to identify GAS within one day, saving time, labor, and money for routine diagnostic microbiology laboratories.

Adult↗
PubMed1999

Coexistence of erythrocyte agglutination and EDTA-dependent platelet clumping in a patient with thymoma and plasmocytoma.

For 8 years, EDTA-dependent pseudothrombocytopenia was observed in a 55-year-old woman with a history of rheumatoid arthritis who had undergone surgery for lymphoepithelial thymoma 11 years earlier. The clinical picture was characterized by the presence of platelet clumps and antiplatelet antibodies of the IgM class. With the recent appearance of a solitary extramedullary plasmocytoma in the right retrobulbar region and the detection of an IgGlambda monoclonal gammopathy, blood examination also revealed erythrocyte agglutinates alongside the platelet clumps and the presence of a cold IgG antibody with antiI specificity. Both phenomena were observed in vitro when the sample temperature declined to 20 degrees C to 25 degrees C, but not at 37 degrees C. While the EDTA-dependent antiplatelet antibodies did not appear to be chronologically correlated with the patient's diseases, the cold antierythrocyte autoantibodies were strictly related to the plasmocytoma and the IgGlambda monoclonal component in serum. To our knowledge, this is the first description of an association between EDTA-dependent platelet and erythrocyte agglutinates, with a clinical picture of pseudothrombocytopenia and pseudoerythrocytopenia due to cold agglutinins.

Blood Cell Count↗
PubMed1979

Mixed cell agglutination reaction of ABO substances in the saliva and determination of human-type ABO blood groups in the cynomolgus monkey.

For detection of ABO substances in the saliva of the cynomolgus monkey, the mixed cell agglutination reaction (MCAR) gave specific and clear results with a very small amount of saliva. Anti-A and anti-B antibodies in the sera of the same species showed the clearest hemagglutination by the saline agglutination method. The combined use of both methods was demonstrated to be easily and accurately applicable to the determination of human-type ABO blood groups of the cynomolgus monkey.

ABO Blood-Group System↗
PubMed1998

Human African trypanosomiasis: a latex agglutination field test for quantifying IgM in cerebrospinal fluid.

LATEX/IgM, a rapid agglutination test for the semi-quantitative detection of IgM in cerebrospinal fluid of patients with African trypanosomiasis, is described in this article. The lyophilized reagent has been designed for field use and remains stable at 45 degrees C for one year. The test has been evaluated on cerebrospinal fluid samples from trypanosome-infected and non-infected patients, by comparison with commercial latex agglutination, radial immunodiffusion, and nephelometry. All test systems yielded similar results.

Evaluation Studies as Topic↗
PubMed1999

Inverse association between IgG-anti-kappa and antierythrocyte autoantibodies in patients with cold agglutination.

It has been known for a long time that IgG-anti-F(ab')(2) antibodies (Abs) are able to suppress the B-cell response. We showed that natural IgG-anti-F(ab')(2) autoantibodies appear in the serum of patients with cold agglutination. If the anti-F(ab')2 Ab suppresses cold agglutinin (CA)-producing B cells, one would expect an inverse correlation between the titers of these two Abs. Our study confirmed this correlation. Subsequent experiments showed that some anti-F(ab')(2) Abs bind to the hinge region of IgG. It was difficult to explain how this Ab suppresses CA-producing B cells, which are of IgM isotype. Here we show that patients with cold agglutination have an IgG-anti-kappa light chain autoantibody in their serum. This is another member of the anti-F(ab')(2) Ab group. Because the vast majority of CAs are IgM-kappa Abs, the anti-kappa Ab might suppress CA-producing B cells. If this is the case, there should be an inverse association between the titer of anti-kappa Ab and CA. In a group of 302 patients, we found that high titers of the anti-kappa Ab correlate with low titers of CA and vice versa (P =.009). Interestingly, this association is found only in patients whose disease is caused by noninfectious agents, including mainly B-cell proliferations (P =.0058). Our data show that the inverse correlation is not confined to a particular CA autoantibody specificity. The results are discussed in the light of recent findings showing that anti-IgM Abs may either inactivate or kill tumoral B cells by apoptosis.

Anemia, Hemolytic, Autoimmune↗
PubMed1999

Automated latex agglutination and ELISA testing yield equivalent D-dimer results in patients with recent myocardial infarction. THROMBO Research Investigators.

Our previous prospective study of post-infarction patients described a strong and significant association of increased plasma D-dimer concentrations in those who experienced a subsequent coronary death or non-fatal myocardial infarction. In the present study, we compare results on stored plasma obtained two months after the index myocardial infarction from 1,038 patients of this trial, using a simple automated latex agglutination (LA) assay in parallel with the standard ELISA test. Results show a somewhat higher mean value for the LA assay (702+/-1092 vs. 638+/-986 ng/ml, p = 0.0002), a strong linear correlation of the two assays (r = 0.86) and 88% agreement for values below 500 ng/ml by the ELISA test. D-dimer concentrations determined by each assay were highly correlated in patients with subsequent coronary artery events (p = 0.93) and quartile values for both the LA and ELISA were equally predictive of such events (p = 0.003 and p = 0.001, respectively). This is the first demonstration that a latex agglutination assay for D-dimer can be used to assess the prognostic risk of recurrent coronary thrombotic disease after myocardial infarction

Adult↗
PubMed1999

Meningitis antigen detection: interpretation of agglutination by ultrasound-enhanced latex immunoassay.

Detailed instructions for performance and interpretation of ultrasound-enhanced latex agglutination tests for the rapid identification of bacteria causing meningitis are described. This recently developed technique, which enhances the sensitivity of most latex immunoagglutination assays, has been studied mainly in the context of detection of antigens of meningitis-causing bacteria. The test concentrates on the Wellcogen bacterial antigen kit (Murex Diagnostics Ltd) that contains five latex suspensions specific for Haemophilus influenzae type b, Neisseria meningitidis ACYW135, N. meningitidis B/Escherichia coli K1, Streptococcus group B and Streptococcus pneumoniae. Light photomicrographs of positive agglutination are shown. Particular attention is paid to the appearance of the latex in negative control samples following exposure to ultrasound. Guidance is given on interpretation and assessment in clinical samples.

Antigens, Bacterial↗
PubMed2000

[Evaluation of the usefulness for the latex agglutination test for serodiagnosis of Mycoplasma pneumoniae infections].

The usefulness of latex agglutination test prepared in our laboratory for the diagnosis of M. pneumoniae infections was assessed. A total of 628 serum samples obtained from patients with respiratory tract infections were tested by complement fixation test and by latex test, from among them 274 serum samples were additionally tested by ELISA--Ig A/--IgG/--IgM and by immunoelectroprecipitation test. The highest sensitivity and specificity was displayed by the latex test in relation to ELISA when determining mycoplasmal antibodies of IgM class (respectively 82.1% and 89.6%) and to the complement fixation test (81.0% and 89.0%). Positive latex test results in our investigations were associated only with the presence of IgM antibodies and were not dependent on the IgA and IgG antibody classes. The latex agglutination test may be used in routine serodiagnosis of mycoplasmosis under condition that the results obtained in this test will be confirmed by the complement fixation test or ELISA.

Enzyme-Linked Immunosorbent Assay↗
PubMed2001

[Polystyrene latexes in agglutination tests: preparation and sensibilization].

A method for preparing polystyrene latexes for slide agglutination test is described. The latexes were used for preparing latex slide tests for evaluating C-reactive protein and myoglobin. Effects of such factors as pH, temperature, antibody concentration, and latex particles concentration, on sensitization and agglutination have been studied. The proposed approaches allow detection of the antigen in a concentration of less than 200 micrograms/liter for myoglobin and less than 8 mg/liter for C-reactive protein.

Animals↗