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At least 19 recordsLinked to original sources
PubMed1979

False-positive reactions in the rapid plasma reagin-card, fluorescent treponemal antibody-absorbed, and hemagglutination treponemal syphilis serology tests.

Sera from 628 nonsyphilitic individuals were tested with the Rapid Plasma Reagin-Card, Fluorescent Treponemal Antibody-Absorbed, and Hemagglutination Treponemal Test for Syphilis tests to ascertain the comparative specificity of these tests. Many sera were also tested with the quantitative Venereal Disease Research Laboratory test. Sera included in the study were from both normal individuals and patients with a variety of illnesses and conditions. The Hemagglutination Treponemal Test for Syphilis gave the lowest overall percentage of false-positive reactions (1.6%), followed by the Fluorescent Treponemal Antibody-Absorbed test (3.3%) and the Rapid Plasma Reagin-Card test (10.8%).

Adult↗
PubMed1979

False positive reactions in the indirect fluorescent antibody test for Legionnaires' disease eliminated by use of formolised yolk-sac antigen.

The indirect fluorescent antibody (FA) technique for the diagnosis of Legionnaires' disease was used to investigate an outbreak of respiratory disease in a military population. The outbreak was later shown to be caused by an adenovirus. High titres were obtained using the ether-killed antigen supplied by the Center for Disease Control (CDC), Atlanta, but not with a formolised yolk-sac antigen prepared in out laboratory. The reactivity of these sera with the CDC antigen was removed by absorption with a partly identified gram-positive bacterium, whereas sera from persons with true Legionnaires' disease were unaffected by such treatment, suggesting that such reactivity is not specific for Legionnaires' disease. The lack of reactivity with negative control sera and strong reactivity from a small group of patients in whom seroconversion was demonstrated has led us to conclude that formolised yolk-sac antigen is a reliable antigen for the diagnosis of Legionnaires' disease by the FA method. Measurement of the sensitivity and specificity of the formolised yolk-sac antigen is still in progress.

Adenovirus Infections, Human↗
PubMed1979

Evaluation of three serological tests for the diagnosis of hydatid disease.

A number of techniques is used for the serological diagnosis of hydatid disease; however previous investigations suggest variable degrees or reliability for each test. This study reports an evaluation of the sensitivity and specificity of three commonly used serological tests for hydatid disease; complement fixation (CF), haemagglutination (HA) and the fluorescent antibody (FA) techniques. The results of these serological tests are compared in a series of specimens from 116 hospital patients, 21 of whom were confirmed surgically as having hydatid disease. A similar high degree of sensitivity was found for each of the three serological tests examined. The CF and HA tests gave negative results in two patients with confirmed hydatid disease, and the result of the FA test was negative in only one patient. The HA test was the most specific with no false positive reactions, but only two false positive reactions occurred with the FA test. The CF test was the least specific as the reaction was positive in nine patients without hydatid disease. When the results of both FA and HA tests were considered together, all 21 cases of hydatid disease were detected and false positive reactions occurred in only two patients.

Complement Fixation Tests↗
PubMed1977

Rapid detection of antibodies to cytomegalovirus by counterimmunoelectrophoresis.

A new method for the detection of precipitating antibody to cytomegalovirus by counterimmunoelectrophoresis (CIEP) is described. Fourteen of 15 adult sera (95%) with IgM-specific antibodies (as detected by immunofluorescence) and complement-fixing antibodies to cytomegalovirus in high titers gave positive reactions by this method. Control sera from 156 patients and 40 normal subjects were negative by CIEP. One of 32 individuals acutely infected with other members of the herpesvirus group gave a positive reaction (3%). False-positive reactions were restricted to a group of sera containing rheumatoid factor (10 of 31), but this activity could be eliminated by preliminary absorption of the sera with aggregated gamma-globulin. The present findings demonstrate that CIEP is useful for the detection of precipitating antibodies to cytomegalovirus in sera from acutely infected patients and promises to be a rapid, inexpensive screening procedure of diagnostic value.

Adult↗
PubMedDate not supplied

Comparison of three techniques for the detection of antibodies to double-stranded DNA: immunofluorescence on Trypanosoma gambiense, immunofluorescence on Crithidia luciliae and radioimmunoassay using the Farr technique.

Three techniques for the detection of antibodies against double-stranded DNA were compared: two immunofluorescent (IF) techniques using either Trypanosoma gambiense or Crithidia luciliae as antigen and a radioimmunoassay (RIA) based on the Farr technique. The IF on T. gambiense or C. luciliae gives very similar results but the reaction on C. luciliae is easier to read and to interpret. The use of C. luciliae permits the swift elimination of the two main causes of errors: antibodies against the nucleus of Trypanosomidae and antibodies reacting with the base of the flagella. The RIA appears as a very sensitive test since six sera gave a positive reaction with the RIA and a negative reaction with the IF on C. luciliae. However, the RIA gives in nine cases false positive reactions and in four cases false negative results. Those last four sera contained specific antibodies with low avidity for double-stranded DNA.

Animals↗
PubMed1979

Cell-mediated immune responses in cattle adult-vaccinated with Brucella abortus strain 19 and in cattle infected with Brucella abortus field strain.

Cell-mediated immune responses in cattle adult-vaccinated with Brucella abortus strain 19, cattle infected with B abortus field strain, and nonexposed cattle were studied by an in vitro lumphocyte-stimulation test (LST). Lymphocytes were prepared from peripheral bovine blood by the Ficoll-diatrizoate technique, and results were assayed for [3H]thymidine incorporation into DNA by liquid scintillation spectrometry. Serotests and bacteriologic isolation attempts were conducted simultaneously with LST. Lymphocytes from cattle infected with field strains had significantly (P = 0.01) higher specific lymphocyte-stimulation inexposed controls. The LST, the serum standard-tube agglutination test (STT), the Rivanol (RIV) test, and the complement-fixation (CF) test correctly classified cattle from which field strains and strain 19 of B abortus were isolated. The LST was negative in cattle vaccinated with B abortus strain 19 (nonshedding), but the three serotests had many false-positive reactions. The CF test had the least false-positive reaction, followed by the RIV test, and the STT was the least specific. Well before the three serotests became positive, the LST was positive in samples from some cattle during the incubation period of the infection. There was little or no correlation between cell-mediated immune responses (as measured by LST) and serum antibody responses (as measured by STT, RIV test, and CF test) in vaccinated but culture-negative cattle and in some nonvaccinated cattle during the incubation period.

Agglutination Tests↗
PubMed1978

HBsAg immune complex glomerulonephritis.

Out of 97 patients with various forms of glomerulonephritis 10 were found to be HBsAg seropositive. None of these showed HBsAg immunodeposits within the kidney. Direct immunofluorescent kidney staining for HBsAg was observed in 4 out of 87 HBsAg seronegative patients. The HBsAg staining in kidneys was a false positive reaction due to binding of the Fc portion of the fluoresceinated IgG molecules to the IgM RF tissue deposits. The false positive reaction for HBsAg is not revealed by the usual specificity controls for fluorescence staining. The role of HBsAg in glomerulonephritis remains unproven.

Antigen-Antibody Complex↗
PubMed1977

[The phenoloxidase activity in the presence of H2O2, EDTA, and copper (author's transl)].

Investigations performed with cryostat sections of the gut, spleen and lung of the rat have shown, that the substrate of PER H2O2 inhibits the PO activity in dependence of the concentration, and that obvious the PO substrate DOPA is no suitable H2-donator for the PER reaction. Therefore a false positive reaction by the PO proof is not to be expected. Copper sulfat does not influence the PO reaction, but it accelerates melanin formation, which causes an unspecific colouring of the tissue.

Animals↗
PubMed1976

[Lymphocyte transformation test in Gell's and Coombs' drug reactions].

A method of interpretation of the lymphocyte transformation test is described which results on the basis of statistical evaluation. With this method good results were received in cases of drug induced side effects of type I according to Gell and Coombs. The investigations on 61 patients have shown that differneces between the clinical findings and lymphocyte transformation tests are rare. They are mainly in relation to false-positive reactions of the lymphocyte transformation test in Penicillin allergy.

Diagnostic Errors↗
PubMed1978

Complement fixation antibody test for human nocardiosis.

Complement-fixing antibody was detected in 13 of 16 patients with histological and/or culture evidence of infection with Nocardia species. The antigen used was a filtrate of soluble substances secreted into liquid growth medium by cultures of N. asteroides. Apparent false positives reactions were found in three of three patients with leprosy and two of five patients with tuberculosis--results similar to some previously reported methods. N. asteroides and mycobacteria share antigens. Only the false positives with tuberculosis are considered a diagnostic problem. No reactions were obtained with sera from 26 patients with other infections and 41 unifected individuals. Whereas previous nocardia serodiagnostic methods have a sensitivity of approximately 50%, our overall sensitivity (81%) compares favorably and included 9 of 11 positive tests in immunocompromised nocardiosis patients (a source of false negative reactions with previous methods).

Adult↗
PubMed1979

False-positive test results for syphilis in relatives of a patient with systemic lupus erythematosus.

In a family of nine members, two had systemic lupus erythematosus and seven positive serological test results for syphilis. None of the affected subjects had a history or physical signs of syphilis, but two had positive results to the Treponema pallidum immobilisation test. The explanation for these findings is not known, but possibily they were all false-positive reactions.

Adolescent↗
PubMed1979

Microimmunodiffusion test for nocardiosis.

Sera from 71 patients with culturally proven nocardiosis were tested for precipitins against a pool of Nocardia asteroides and N. brasiliensis culture filtrates and against antigens from the supernatant of homogenized N. asteroides cells. A human nocardiosis case serum was used as a reference. Sera from 56 of the 71 cases were reactive with either the culture filtrate antigen, the homogenate antigen, or both antigens, resulting in an overall sensitivity of 79%. Sera from 35 of the patients (49%) were positive with the homogenate antigens, and 28 (39%) showed bands of identity with the reference serum. Sera from 50 nocardiosis cases (70%) were positive with the pooled culture filtrate antigens, and 29 (41%) produced bands of identity with the reference serum. Of 89 sera from patients with various systemic mycotic diseases, tuberculosis, or actinomycosis, 24 (27%) were positive with the nocardial homogenate antigens and 4 (4.5%) showed precipitin bands of identity. Thirty-five of the 89 sera (42%) were positive with the nocardial culture filtrate antigens, and 6 (6.7%) showed bands of identity. The majority of sera demonstrating false-positive reactions were from tuberculosis and actinomycosis cases. One of seven sera from well individuals produced a precipitin band with the culture filtrate antigen, but this was not a band of identity with reference serum. These antigens did not distinguish antibodies from patients with N. asteroides, N. brasiliensis, or N. cavia infections.

Actinomycosis↗
PubMed1979

[Methods for the detection of antibodies to native (double stranded) DNA (author's transl)].

Three different methods adequate for routine work, i.e. hemagglutination, counterimmunoelectrophoresis and radioimmunoassay, were used in the past in our laboratory to detect antibodies to native (double stranded) DNA. There was a high incidence of false positive or false negative results by counterimmunoelectrophoresis. Hemagglutination reaction was less sensitive in detecting anti-nDNA than was radioimmunoassay. Natural DNA preparations and a synthetic polynucleotide (3H-dAT) were used as antigenic substrates in radioimmunoassay providing well correlating binding values.

Antibodies↗
PubMed1979

Detection of the K99 antigen of Escherichia coli in calf faeces by enzyme-linked immunosorbent assay (ELISA).

An enzyme-linked immunosorbent assay (ELISA) is presented for the detection of the K99 antigen of Escherichia coli in calf faeces. False-positive reactions were not observed with K99-negative strains and with several viral antigens. Only bovine coronavirus caused slight positive reactions which could be eliminated by a blocking test. As compared with the conventional procedure for the detection of the K99 antigen, ELISA seemed to be a least as sensitive and had the advantage that samples could be stored at --20 degrees C before testing. In addition many samples could be handled at the same time and the results became available quickly. By carrying out the assay as a blocking test, specific antibody against K99 in serum or colostrum could be detected and titrated.

Animals↗
PubMed1976

Positive skin reactions to gluten in coeliac disease.

Following intradermal challenge with a peptic-tryptic digest of gluten, visible Arthus-type skin reactions were observed in 33 per cent of a group of 55 adults with coeliac disease. Of the 23 with untreated disease positive skin reactions occurred in 52 per cent. There was an invariable association between serum gluten antibodies and the presence of a skin reaction to gluten, indicating that gluten antibody combination with gluten in the skin provides the basis of the skin response. Since no false positive reactions were found in 52 normal controls, skin testing with gluten may provide a useful adjunct to the diagnosis and management of coeliac disease, especially in the outpatient department.

Adult↗