Elevated anti-streptococcal antibodies in patients with recent narcolepsy onset.
(17/59)
STUDY OBJECTIVES: Narcolepsy-cataplexy has long been thought to have an autoimmune origin. Although susceptibility to narcolepsy, like many autoimmune conditions, is largely genetically determined, environmental factors are involved based on the high discordance rate (approximately 75%) of monozygotic twins. This study evaluated whether Streptococcus pyogenes and Helicobacter pylori infections are triggers for narcolepsy. DESIGN: Retrospective, case-control. SETTING: Sleep centers of general hospitals. PARTICIPANTS: 200 patients with narcolepsy/hypocretin deficiency, with a primary focus on recent onset cases and 200 age-matched healthy controls. All patients were DQB1*0602 positive with low CSF hypocretin-1 or had clear-cut cataplexy. MEASUREMENTS AND RESULTS: Participants were tested for markers of immune response to beta hemolytic streptococcus (anti-streptolysin O [ASO]; anti DNAse B [ADB]) and Helicobacter pylori [Anti Hp IgG], two bacterial infections known to trigger autoimmunity. A general inflammatory marker, C-reactive protein (CRP), was also studied. When compared to controls, ASO and ADB titers were highest close to narcolepsy onset, and decreased with disease duration. For example, ASO > or = 200 IU (ADB > or = 480 IU) were found in 51% (45%) of 67 patients within 3 years of onset, compared to 19% (17%) of 67 age matched controls (OR = 4.3 [OR = 4.1], P < 0.0005) or 20% (15%) of 69 patients with long-standing disease (OR = 4.0 [OR = 4.8], P < 0.0005]. CRP (mean values) and Anti Hp IgG (% positive) did not differ from controls. CONCLUSIONS: Streptococcal infections are probably a significant environmental trigger for narcolepsy. (+info)
Evaluation of a new latex agglutination test for detection of streptolysin O antibodies.
(18/59)
Acute- and convalescent-phase serum specimens were collected from 50 patients with group A streptococcal pharyngitis. The anti-streptolysin O (ASO) titer for each serum specimen was determined by using both the standard neutralization assay and the latex agglutination (LA) test (Rheumagen ASO; Biokit Inc., New Britain, Conn.). When the ASO titers derived by the two methods were compared, the correlation coefficient was 0.93. When the ability of the LA test to demonstrate a significant ASO titer rise (greater than or equal to 2 dilutions) was compared with that of the standard neutralization assay, the LA test had a sensitivity of 91%, a specificity of 86%, a positive predictive value of 83%, and a negative predictive value of 92%. Triplicate LA test determinations were performed on a subset of 31 serum specimens, and for 29 (94%), the repeated ASO titers were all within 1 dilution of each other; the width of the 95% confidence interval for the triplicate measurements of each serum specimen was +/- 32.8 IU. We found the Rheumagen ASO to be a simple, rapid LA procedure for measuring ASO titers that produces results that are highly reproducible, show little lot-to-lot variability, and are comparable to the ASO titers obtained with the standard neutralization assay. (+info)
Comparison of three rapid methods for detection of antibodies to streptolysin O and DNase B.
(20/59)
Three commercial systems were compared for ability to detect antibodies to streptolysin O (ASO) and DNase B (ADB). Streptozyme (Wampole Laboratories, Cranbury, N.J.) exhibited high sensitivity (100%) for detecting ASO but low sensitivity for ADB (22.2%). The LeapStrep (Organon Teknika, Malvern, Pa.) and Check-Spectra (Diagnostic Technology, Hauppauge, N.Y.) tests had low sensitivities for detecting ASO (35.3 and 21.4%, respectively) and ADB (22.2 and 33.3%, respectively). (+info)
Comparison of latex and haemolysin tests for determination of anti-streptolysin O (ASO) antibodies.
(21/59)
A latex agglutination test was compared with the micro-titration haemolysin inhibition method for the detection of anti-streptolysin O (ASO) antibodies in 428 serum samples. After slight modification of the latex method to produce maximal agglutination good agreement was shown between the results obtained by the two methods. The latex test had a sensitivity of 83.6%, a specificity of 93.3%, a predictive positive value of 86.5% and a predictive negative value of 91.6%. It was convenient, required less labour than the haemolysin test, and permitted economic testing of small numbers of sera. (+info)
Homogeneous liposome lysis assay for determination of anti-streptolysin O antibody titer in serum.
(22/59)
We developed a liposome lysis assay for determining anti-streptolysin O antibodies (ASO) in human sera involving the use of carboxyfluorescein-entrapped multilamellar liposomes. This assay system was based on the inhibition of streptolysin O-induced liposome lysis by ASO. Briefly, after incubation of a given amount of streptolysin O with ASO for 30 min at 37 degrees C, carboxyfluorescein-entrapped liposomes composed of egg yolk phosphatidylcholine and cholesterol in a molar ratio of 1:1 were added to the mixture to determine the residual streptolysin O activity. Liposome lysis, detected as carboxyfluorescein release from the liposomes, was inversely proportional to the ASO titer. The results of within-run and between-run precision studies indicated that the liposome lysis assay is accurate and gives reproducible data. Bilirubin, hemoglobin, and triglycerides did not interfere with the liposome lysis assay. The ASO titers of 100 patient sera, evaluated by our new method and the Rantz-Randall method, showed good correlation. (+info)
Sera from patients with high titers of antibody to streptolysin O react with listeriolysin.
(23/59)
Sera of patients with suspected rheumatic fever and elevated titers of antibody to streptolysin O were examined by an immunoblotting technique. All but two serum samples, which yielded relatively low titers, bound to a 60-kilodalton protein in the supernatant from a culture of Listeria monocytogenes, which presumably represents the listeriolysin. (+info)
New hemolytic method for determination of antistreptolysin O in whole blood.
(24/59)
A new method is proposed for the determination of antistreptolysin O, based on the properties of streptolysin O. The reduced form of the toxin is hemolytic, whereas the oxidized form is not; this activity can be restored, however, by a reducing agent. Both forms maintain the capacity to bind specific antibodies. Unlike the classical method, the assay is performed on whole blood, using the patient's own erythrocytes as revealing agents. A procedure is proposed which limits the operation to a single dilution of a microvolume of blood (0.05 ml brought to 2 ml) and to the distribution of constant quantities in test tubes prefilled with different amounts of oxidized streptolysin O. After a few minutes, a reducing agent is added, and the reading is performed as in the classical technique after sedimentation of the erythrocytes. Correlation with the traditional method (r = 0.987) is evaluated on the basis of the results of samples from hospitalized patients. (+info)