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At least 109 records · Page 6Linked to original sources
PubMed1976

Studies on the origin of false positive reactions to the complement-fixation test for contagious bovine pleuropneumonia.

Serums of cattle free from contagious bovine pleuropneumonia (CBPP) were tested in complement fixation (CF) tests using 3 antigens; these were the standard antigen (SA) used to test to CBPP in Australia, an ethanol extract antigen (EA) also prepared from Mycoplasma mycoides subsp. mycoides (M. mycoides) and an antigen prepared from a Group 7 bovine mycoplasma isolated from arthritis (AA). The serums included 146 which fixed complement with SA. Eighty percent of these false-positive serums reacted with AA but not with EA; the other 20% were positive at low titre with EA but gave no reaction with AA. Attempts were made to produce false-positive serums experimentally by inoculating 3 Group 7 mycoplasmas and 2 Mycoplasma bovigenitalium strains into cattle. Serums from 3 of 9 cattle inoculated with strain L2917 (Group 7) reacted with SA but differed from the false-positive serums of field cattle by reacting with all 3 antigens. Tests with serums from cattle experimentally infected with CBPP gave similar titres with SA and EA, but the results with AA were mostly negative or less than 10% of the titres obtained with SA and EA. The results of CF tests on serums from the experimental cattle, after absorptions with suspensions of the mycoplasmas, showed that there was a one-way serological relationship between strain L2917 and M. mycoides and between this Group 7 strain and M. bovigenitalium. The CF tests with 3 antigens have assisted in demonstrating the false-positive nature of the reacting field serums encountered in the course of routine CF tests for CBPP in cattle in Australia.

Absorption↗
PubMed1988

Rheumatoid factor isotypes in patients with rheumatoid arthritis and in subjects with "false-positive" reactions.

The appearance of RFs, as detected by standard serological techniques, often precedes the onset of clinical RA by years. This pre-rheumatoid immunological reactivity is not associated with C-reactive protein response or occurrence of antibodies against native type II collagen. The profile of RF isotypes appeared to be similar between pre-rheumatoid and rheumatoid sera. RA sera contained somewhat more frequently IgG and IgA class RFs than "false-positive" sera from a community-based population sample. 7S IgM could be detected at about the same frequency in rheumatoid sera, in RF-positive pre-rheumatoid sera and in sera with "false-positive" RF reactions. The significance of the findings in terms of the pathogenesis of RA will be discussed.

Adult↗
PubMedDate not supplied

False positive reaction for carboxyhemoglobin in blood from liver tissue.

On spectrophotometric determination of carboxyhemoglobin in blood collected from the liver of three bodies at three days post-mortem, false positive results were found (5--15 per cent saturation), since samples of heart blood collected a few hours after death did not contain carboxyhemoglobin.

Accidents, Aviation↗
PubMed1990

Comparison of false-positive reactions in direct-binding anti-HIV ELISA using cell lysate or recombinant antigens.

In a 2-year study of false-positive anti-HIV-1 tests in blood donors at Manchester and Lancaster Blood Banks, the reactions associated with a HIV-infected cell lysate antigen were compared with those using recombinant-antigen-based tests. In year 1 (cell lysate test) at Manchester BTS 0.21% of 119.178 donations were repeatedly reactive, compared with 0.53% of 119,004 donations in year 2 (recombinant antigen). Reactive sera were tested at Manchester PHL by three different immunoassays. Referred specimens were classified as anti-HIV positive (95-100% reactive in all the assays), equivocal or negative (negative results in all three immunoassays). Two donors were confirmed to be anti-HIV positive over the 2-year period. Most sera were negative by confirmatory immunoassays in years 1 and 2. In year 1, a study of 60 referred sera with sex- and age-matched controls showed high correlation between a reactive anti-HIV-1 screening test and indeterminate anti-HIV-1 patterns on Western blot showing reactions with HIV gag-coded proteins. In year 2, less than 10% of referred sera were reactive by Western blot, and there was no correlation between a reactive screening anti-HIV test, the strength of signal in the test or a reactive Western blot. Follow-up showed that donors whose sera were reactive in years 1 and 2 by the anti-HIV-1 screening test formed almost two different populations. Four donors with equivocal anti-HIV-1 confirmatory tests had anti-HIV 'envelope' reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗