Autoantibody profiles in canine ANA-positive sera investigated by immunoblot and ELISA

Canine systemic lupus erythematosus (SLE) has a similar disease expression as human SLE, but the serological characterisation of the canine disease is as yet incomplete. In the present study, we examined the specificity of antinuclear antibodies (ANA) in indirect immunofluorescence (IIF) positive canine sera. Sixty-four canine IIF ANA positive sera were characterised using HeLa cell nuclear extract immunoblots and recombinant U1-70K ELISA. We compared these results with a previously shown concordance between indirect immunofluorescence and immunodiffusion in canine SLE serological diagnosis. One canine serum reacting with Sm proteins was observed, and five canine sera presented anti-RNP autoantibodies against the antigens 70K, A, C, and/or B/B'. The autoantigen most frequently recognised was a 43 kDa nuclear protein, previously described as hnRNP G. This prominent canine autoantigen was missing in the commercially available extract designed for immunodiffusion testing of human sera. Other prominent canine autoantigens were found not to be identical with the principal human ones, thus making present human test systems deficient for the use in canine systemic connective disease diagnosis. The development of antigenic extract designed for canine autoimmune autoantigens is necessary in order to make immunodiffusion a useful method in canine diagnosis. The anti-RNP positive canine sera were examined in more detail and we found that the human major antigenic region of the most prominent RNP antigen, the U1-70K protein, also is targeted by canine autoantibodies. Thus, the response against the RNP antigen seems to be conserved between man and dog.     

Positivity for antinuclear antibody in patients with advanced rheumatoid arthritis

Some patients with rheumatoid arthritis (RA) as well as those with other collagen diseases are positive for antinuclear antibody (ANA). We investigated the frequency of positivity for ANA in 104 patients with RA and evaluated the clinical features and laboratory data in the ANA-positive and -negative groups. The presence of ANA in sera was studied by indirect immunofluorescence using HEp-2 cells as the antigen substrate. Sera with a positive fluorescence at a dilution of 1:20 were considered to be positive for ANA. Of the 104 patients, 39 (37.5%) were positive for ANA. The staining pattern in the positive cases varied, but most were speckled (64.1%) and homogeneous (48.7%). A small number showed a nucleolar (20.5%) or a centromere (10.3%) pattern. None showed a shaggy pattern. The ANA titer was lower in RA patients compared with those with other collagen-related diseases such as systemic lupus erythematosus or progressive systematic sclerosis. None of the patients positive for ANA with either a nucleolar or centromere staining pattern had progressive systemic sclerosis or the CREST syndrome. One patient each had Raynaud's phenomenon and pulmonary fibrosis. There was no correlation between ANA positivity and indicators of joint inflammation. The prevalence of ANA positivity in patients with advanced or prolonged disease was higher than those with early stages or short durations. There was no correlation with drug therapy.     

Antinuclear antibodies and patterns of nuclear immunofluorescence in type 1 autoimmune hepatitis

To determine the significance of antinuclear antibodies and their patterns of indirect immunofluorescence in type 1 autoimmune hepatitis, sera from 99 patients were evaluated. Patients with antinuclear antibodies had a lower frequency of liver transplantation (6% vs 22%, P = 0.04) than seronegative patients. They were also more commonly HLA-DR4-positive than seronegative patients (56% vs 30%, P = 0.05) and normal subjects (56% vs 30%, P = 0.004). The 42 patients with antinuclear antibodies and a diffuse pattern of indirect immunofluorescence had higher serum titers of ANA (serum titers > or = 1:500, 71% vs 14%, P < 0.0001) and SMA (serum titers > or = 1:500, 69% vs 27%, P = 0.003) than the 22 patients with antinuclear antibodies and a speckled pattern. These patients, however, were otherwise not distinguished by clinical features and treatment response. Patients with a speckled pattern had A1-B8-DR3 more frequently than patients with a diffuse pattern (65% vs 23%, P = 0.005) and normal subjects (65% vs 13%, P < 0.0001), but they had no other salient features. We conclude that patients with antinuclear antibodies have a better long-term prognosis than seronegative patients, and they have HLA-DR4 more commonly. The patterns of indirect immunofluorescence associated with ANA positivity have no practical clinical implications.     

Discordant twins with Parkinson''s disease: positron emission tomography and early signs of impaired cognitive circuits

Anti-neutrophil cytoplasmic antibodies (ANCA) in sera from 52 patients with rheumatoid arthritis (RA), including 9 patients with malignant RA (MRA) and 20 healthy controls were examined by indirect immunofluorescence technique (IIF). Nine out of 52 RA patients showed positive ANCA staining. None of MRA patients had, however, ANCA in sera. The staining pattern for ANCA was either perinuclear for 4 sera or non-specific for 5 sera, but not cytoplasmic. Furthermore, anti-nuclear antibodies (ANA) in 9 ANCA positive RA sera were tested by IIF, using Hep-2 cells. Six sera had positive ANA. Three sera showed as nucleolar and 1 serum as centromere in ANA staining pattern. The incidence of these ANA staining pattern in ANCA positive sera (4 out of 9) was higher than in ANCA negative sera (1 out of 19). The clinical profiles and laboratory findings of 9 RA patients with positive ANCA revealed that they had suffered and treated for more than 10 years and had still active joint inflammation, like intractable RA. These results indicate that ANCA in RA are not associated with vasculitis.     

Antibodies to single-stranded and double-stranded DNA in antinuclear antibody-positive type 1-autoimmune hepatitis

To determine the significance of antibodies to single-stranded (anti-ssDNA) and double-stranded DNA (anti-dsDNA) in antinuclear antibody (ANA)-positive type 1 autoimmune hepatitis, sera from 53 patients were tested by enzyme immunosorbent assay (ELISA) and indirect immunofluorescence using the Crithidia luciliae substrate. Anti-dsDNA were detected in 18 patients (34%) by ELISA and 12 patients (23%) by the Crithidia-based assay. Twenty patients with anti-dsDNA by either assay (38%) had higher serum levels of immunoglobulin G (3971 +/- 270 mg/dL vs. 3201 +/- 247 mg/dL, P = .05) than seronegative patients. They also had human leukocyte antigen (HLA) DR4 more commonly than other patients (83% vs. 41%, P = .006) and normal subjects (83% vs. 30%, P = .00007). In contrast to patients seropositive by the Crithidia-based assay, those seropositive by ELISA failed corticosteroid therapy more commonly (24% vs. 3%, P = .04). Anti-ssDNA were found in 45 patients (85%) and they did not distinguish patients with different clinical features or outcomes. We conclude that anti-dsDNA are common in ANA-positive type 1 autoimmune hepatitis. HLA DR4 is associated with their production, and seropositivity by ELISA characterizes patients who have a poorer immediate response to corticosteroid treatment. Anti-ssDNA are common but they do not have important clinical implications.     

Antinuclear autoantibodies in human T-cell leukemia/lymphoma virus type I carriers in French Guiana

To compare the rate of antinuclear antibodies (ANA) in HTLV-I carriers and negative individuals in French Guiana, 350 sera (175 HTLV-I carriers, either symptomatic or not, and 175 controls) were screened for ANA, using an immunofluorescence assay. All positive sera were tested for autoantibodies against extractable nuclear antigens, histones and double stranded DNA. ANA were detected in 9.71% of the HTLV-I carriers and 3.43% of the control group (p < 0.05). There was no difference in ANA distribution by age, sex, or ethnic group. Neither was there any difference between asymptomatic and symptomatic HTLV-I individuals. However, ANA of medical interest were significantly higher (p < 0.04) in HTLV-I seropositive Creoles than in seropositive Noir-Marrons.     

Frequency and significance of antibodies to P450IID6 protein in Japanese patients with chronic hepatitis C

BACKGROUND/AIMS: The aims of the current study were to assess the frequency and the significance of antibodies to cytochrome P450IID6 protein (anti-P450IID6) in various diseases among Japanese patients. METHODS: Sera from 541 patients were tested by indirect immunofluorescence, and the specificity of anti-P450IID6 was ascertained by either enzyme immunoassay (ELISA) or Western blot using recombinant antigen or rat liver microsomes. RESULTS: Anti-P450IID6 was found in only 6 of 235 patients (2.6%) with chronic active hepatitis (CAH) positive for hepatitis C virus (HCV) antibody and quantitative HCV-RNA with genotypes II and IV. The predominant epitopes on immunoblots were 66 and 50KD, a 10KD band being the newly underfined microsomal antigen. Even in the patients negative for autoantibodies to nuclear antigens (ANA) by routine indirect immunofluorescence test, various ANA were detected by the newly developed recombinant ELISA. These patients were younger, with lower gamma-globulin and IgG levels than patients with autoimmune hepatitis. Three of five patients with anti-P450IID6 responded well to interferon therapy and one received prednisone when interferon was ineffective. Interestingly, only this patient was diagnosed as definite autoimmune hepatitis according to the criteria proposed by the International Autoimmune Hepatitis Group (IAHG). The other five patients who did not satisfy the IAHG criteria might be considered as CAH-C with autoimmune features. No autoimmune hepatitis patients positive for anti-P450IID6 were identified in the current study, indicating that the variant is very rare in Japan. CONCLUSIONS: Anti-P450IID6 in CAH-C patients in Japan is not as rare as expected. Anti-P450IID6 among Japanese patients has uncertain significance and precludes further characterization of CAH-C with autoimmune features, which might require interferon therapy.     

Reactions to less common species of fire ants

The BP180 antigen, a component of the epidermal anchoring complex, has been identified as one of the major antigenic targets of autoantibodies associated with the blistering skin disease, bullous pemphigoid. Our research group has recently demonstrated that reactivity of bullous pemphigoid autoantibodies to the BP180 ectodomain is almost entirely restricted to a set of four antigenic sites clustered within the membrane-proximal noncollagenous stretch (NC16A). Using a passive transfer mouse model, antibodies to the corresponding noncollagenous region of murine BP180 were shown to trigger an inflammatory subepidermal blistering disease that closely mimics bullous pemphigoid. We now report the development of an enzyme-linked immunoabsorbent assay system that is extremely sensitive in detecting disease-specific autoantibodies in the sera of bullous pemphigoid patients. The target antigen in this assay is a recombinant form of the BP180 NC16A domain that contains all four of the well-defined bullous pemphigoid-associated antigenic sites. Of 50 randomly selected bullous pemphigoid sera tested, 47 (94%) were positive in this assay, whereas no specific reactivity was detected in any of the 107 controls. Interestingly, all three of the bullous pemphigoid sera that were negative in this assay had been obtained from patients who were already undergoing treatment. The NC16A enzyme-linked immunosorbent assay is more sensitive than any of the standard techniques for detecting circulating bullous pemphigoid autoantibodies, including other enzyme-linked immunosorbent assays, immunoblotting, and indirect immunofluorescence. Finally, the NC16A enzyme-linked immunosorbent assay provides immunologic information that cannot be obtained from direct immunofluorescence studies of skin biopsies, and that may well be relevant in the diagnosis and treatment of bullous pemphigoid.     

Pattern of macrophage subpopulations in post-traumatic bone infections after combined operative/antibiotic treatment

Serum samples of 485 uveitis patients were screened for the presence of anti-neutrophil cytoplasmic antibodies using a standardized immunofluorescence test (IIF) on neutrophil granulocytes. Seventeen of these sera contained cytoplasmic (C)-ANCA antibodies, while two of the sera contained perinuclear (P)-ANCA antibodies (both antinuclear antibody (ANA)-positive, one anti-myeloperoxidase (MPO)-positive). None of the C-ANCA-positive sera reacted with proteinase-3 in ELISA using a highly purified proteinase-3 preparation. Four C-ANCA and one P-ANCA-positive serum reacted with MPO. The majority of the sera did react with azurophilic granules in ELISA. The implication of these results is that in patients with uveitis a positive C-ANCA test is not diagnostic for Wegener's granulomatosis, but is most probably caused by the presence of autoantibodies against as yet unknown constituents of azurophilic granules.     

Radioimmunoassay for glutamic acid decarboxylase (GAD65) autoantibodies as a diagnostic aid for stiff-man syndrome and a correlate of susceptibility to type 1 diabetes mellitus

OBJECTIVE: To establish and validate a double-antibody radioimmunoassay (RIA) for detecting serum auto-antibodies against glutamic acid decarboxylase (GAD65). This enzyme catalyzes synthesis of the neurotransmitter gamma-aminobutyric acid in neurons and pancreatic islet cells. MATERIAL AND METHODS: We compared the frequency of GAD65 and other "thyrogastric" autoantibodies in adult patients with stiff-man (Moersch-Woltman) syndrome, type 1 diabetes, or polyendocrine disorders and in healthy subjects. The frequency of pancreatic islet cell antibody (ICA) detection was also assessed. The GAD65 RIA was validated by testing blinded samples, by confirming the specificity of low-titered positive results by "cold" antigen inhibition, and by comparing the RIA results with results of a kit assay incorporating staphylococcal protein A as immunoprecipitant. Recombinant GAD65 protein labeled with 125I was used as antigen, and a combination of anti-human IgG and IgM was used as immunoprecipitant. Seropositivity was determined for ICA and gastric parietal cell antibodies by indirect immunofluorescence assays and for thyroid peroxidase (microsome) and thyroglobulin antibodies by agglutination assays. RESULTS: We detected GAD65-specific antibodies in all but 1 of 46 local patients with stiff-man syndrome (98%); 16 had evidence of diabetes. Positive values exceeded 20 nmol/L in 96%, and 89% were ICA-positive; 76% had additional thyrogastric antibodies. Of 41 patients with type 1 diabetes (17 local and 24 workshop serum specimens), 33 were GAD65 antibody-positive (80%); 85% of these positive values were 20 nmol/L or lower. Only 18% of sera from patients with type 1 diabetes were ICA-positive, but 59% had other thyrogastric autoantibodies. Of 20 patients with autoimmune endocrinopathies without diabetes or stiff-man syndrome, 35% were GAD65 antibody-positive, 5% were ICA-positive, and 90% were thyrogastric antibody-positive. Of 117 healthy control subjects, 8% were GAD65 antibody-positive, and a third of those had other thyrogastric antibodies (14% overall); none was ICA-positive. CONCLUSION: Seropositivity in the double-antibody RIA for GAD65 autoantibody is a sensitive and specific marker of predisposition to type 1 diabetes and related organ-specific autoimmune disorders. As such, this RIA is complemented by assays for thyroid and gastric parietal cell autoantibodies.     

Comparison of immunofluorescence with enzyme immunoassay for detection of Q fever

To evaluate enzyme immunoassay (EIA) as an alternative to indirect immunofluorescence assay (IFA) to screen for Q fever in humans, 157 serum samples from patients suspected of having the disease were tested for immunoglobulin G antibodies to Coxiella burnetii. The agreement between the tests and the sensitivity of EIA were excellent (96.8% and 98.4%, respectively) when an IFA titer of > 1/160 was considered positive. All serum samples with a titer of > 1/320 in the IFA were also positive by the EIA. The EIA seems to be an acceptable alternative to IFA for screening for Q fever.     

Serum IgA antibodies from patients with coeliac disease react strongly with human brain blood-vessel structures

BACKGROUND: Our objective was to determine the possible presence of IgA antibodies directed against human central nervous system (CNS) structures in sera from coeliac disease (CD) patients. METHODS: Serum samples were collected from 4 patients with active CD on a gluten-containing diet, 11 biopsy-proven CD patients on a gluten-free diet (GFD), and 52 non-coeliac gastrointestinal controls. In all patients IgA antigliadin antibody (AGA) titres were determined with enzyme-linked immunoassay (ELISA), and IgA antiendomysium antibodies (EMA) with indirect immunofluorescence on human umbilical cord. Cryostat sections of human brain occipital cortex were incubated with the patients' sera and subsequently labelled with anti-human IgA fluorescein conjugate. RESULTS: All sera from patients with active CD on a gluten-containing diet yielded positive results in both the IgG-AGA and EMA test and in indirect immunofluorescence on brain tissue, disclosing a strong fluorescence over blood-vessels structures. All sera from CD patients on a GFD and from non-coeliac gastrointestinal controls gave a negative result on both the EMA test and the immunofluorescence reaction on human brain. CONCLUSIONS: Sera from patients with active CD contain IgA antibodies that react with human brain vessel structures, giving intense fluorescence. These antibodies are not present in sera from coeliac patients on a GFD or non-coeliac controls. This finding might be involved in the abnormal nervous system manifestations frequently described in association with coeliac disease.     

Characterization and structure of the mitochondrial small rRNA gene of the entomopathogenic fungus Beauveria bassiana

HCV infection and interferon-alpha (IFN-alpha) therapy have been associated with autoimmunity. To assess whether chronic liver disease (CLD) due to HCV infection or its treatment with IFN-alpha cause autoimmune manifestations, the prevalence of tissue autoantibodies in 51 children with chronic HCV infection and 84 with other CLD was analysed by standard techniques. Sixty-five percent of patients with chronic HCV infection, 66% with chronic hepatitis B infection and 60% with Wilson's disease were positive for at least one autoantibody. In the 51 subjects with chronic HCV infection (29 treated with IFN-alpha, 22 untreated), tested on 165 occasions over a median of 9 months (range 5-42 months), autoantibodies to nuclei (ANA), smooth muscle (SMA), gastric parietal cell (GPC) and/or liver kidney microsomal type 1 (LKM-1) were similarly prevalent in treated and untreated patients (90% versus 68%, P = 0.12). Positivity for SMA was present in 67%, GPC in 32%, ANA in 10%, LKM-1 in 8% of cases. Treatment with IFN-alpha had to be suspended due to transaminase elevation in one SMA-positive, one ANA-positive but in three of four LKM-1-positive patients. Our results show that: (i) autoantibodies are common in viral-induced hepatitis and Wilson's disease; (ii) positivity for SMA, GPC, ANA is part of the natural course of chronic HCV infection, their prevalence being unaffected by IFN-alpha; and (iii) IFN-alpha should be used cautiously in the treatment of LKM-1/HCV-positive patients.     

Antineutrophil cytoplasmic autoantibodies in 6 patients with renal failure and systemic sclerosis

OBJECTIVE: To elucidate the distribution and frequency of antineutrophil cytoplasmic autoantibodies (ANCA) in systemic sclerosis. METHODS: Patient sera were analyzed by indirect immunofluorescence and by enzyme linked immunosorbent assay. RESULTS: High titers for perinuclear ANCA correlated with rapid deterioration of renal function. Patients were normotensive with normal plasma renin levels, but anemia, pulmonary hemorrhage and thrombocytopenia were problematic. All patients had anti-myeloperoxidase antibodies and some had anti-nRNP, anti-DNA, anti-Sm and LE cell antibodies. Outcome was poor except for one patient treated by plasmapheresis and cyclophosphamide. CONCLUSION: A renal specific subset of systemic sclerosis is suggested.     

Anti-nuclear antibodies and the optic-spinal form of multiple sclerosis

We found anti-nuclear antibodies (ANA) (1:20 or higher) in sera from 11 of 16 patients with a diagnosis of the optic-spinal form of multiple sclerosis (OpS-MS) and 13 of 59 patients with other forms of MS (other MS), both rates being significant (P = 0.0004). Six of the OpS-MS patients had a high level of ANA (1:80 or higher), while levels were high in only three of the other MS patients, showing a significant difference (P = 0.0022). Titres of ANA were significantly higher in OpS-MS patients than in other MS patients (P < 0.0001). There was no relationship between the presence of ANA and age in OpS-MS patients, while patients with were older than those without high ANA levels among other MS patients. ANA-positive rate and titres were significantly higher in OpS-MS patients than in sex- and age-matched other MS patients. These results support the concept that OpS-MS constitutes a distinct subgroup among patients with a clinical diagnosis of MS and may indicate that systemic dysregulation of the inflammatory or immune response is more common in OpS-MS patients; the possible pathogenetic relevance of ANA-associated vasculopathy to some patients with a clinical diagnosis of OpS-MS should be considered.     

Anti-endothelial cell antibodies in Takayasu arteritis

BACKGROUND: Although a specific etiology for Takayasu arteritis has not been found, the bulk of evidence favors an autoimmune mechanism. We examined the sera of 19 patients with Takayasu arteritis for antineutrophil cytoplasmic antibodies (ANCA), antinuclear antibodies (ANA), anti-DNA antibodies, antibodies to extractable nuclear antigens (ENA), anti-Ro anti-bodies, anticardiolipin antibodies, circulating immune complexes, and anti-endothelial cell antibodies (AECA). METHODS AND RESULTS: We used enzyme-linked immunoassays, immunofluorescence, counterimmunoelectrophoresis, fluorescent-activated cell sorter (FACS) analysis, and confocal microscopy. We found that although no patient had positive ANCA, ANA, anti-DNA antibodies, ENA antibodies, anti-Ro antibodies, or anticardiolipin antibodies, 18 of the 19 patients had AECA. The AECA titers of the patients were 2561 +/- 1458 compared with 126 +/- 15 arbitrary units in a normal group of control subjects (P < .001). To verify the specificity of AECA, we performed cytofluorimetry on human endothelial cells with the sera from patients and control subjects. Two entirely separate patterns of fluorescence intensity were identified. We next performed immunocytochemistry and confocal microscopy with human endothelial cells subjected to patients' sera and to sera from normal subjects. The cells subjected to sera from patients with Takayasu arteritis demonstrated specific immunofluorescent staining of their plasma membrane and cytosol. CONCLUSIONS: AECA are frequently present in patients with Takayasu arteritis. They may play a role in the pathogenesis. Furthermore, they may be useful as an additional diagnostic tool.     

Serum autoantibodies in chronic hepatitis C: comparison with autoimmune hepatitis and impact on the disease profile

Antibodies to nuclei (ANA), smooth muscle (SMA), and liver/kidney microsomes type 1 (anti-LKM1) may occur in chronic hepatitis C. Distinct subspecificities, including ANA with the homogeneous pattern (ANA-H) and SMA with antiactin specificity (SMA-AA), are found in autoimmune hepatitis (AIH). This study was performed to characterize the hepatitis C virus (HCV)-associated autoantibodies and to evaluate their influence on the profile of the disease. Two hundred ninety consecutive patients with chronic hepatitis C and 35 control cases with AIH were screened for autoantibodies by indirect immunofluorescence (IFL) at 1:40 serum dilution. The ANA pattern was defined by IFL on HEp-2 cells and the SMA-AA identified by the presence of at least two of the following elements: 1) SMA(T) or SMA(G) pattern by IFL on kidney sections; 2) XR1 precipitating system by counterimmunoelectrophoresis; or 3) typical pattern by IFL on liver sections from phalloidin-intoxicated rats. ANA, SMA, and anti-LKM1 occurred in 9%, 20%, and 6% of chronic hepatitis C cases, respectively. The overall prevalence of autoantibodies was 30% (87 of 290). Compared with AIH, HCV-associated ANA and SMA exhibited ANA-H and SMA-AA at a lower prevalence (38% vs. 71%, P = .04 and 8% vs. 87%, P < .000001, respectively) and had a lower median titer (1:80 vs. 1:320, P < .001 and 1:40 vs. 1:320, P < .000001, respectively). The concomitant positivity for ANA-H and SMA-AA was detected in none of the HCV cases, but in 46% of AIH sera (P < .000001). Two parameters were independently associated with the autoantibodies in chronic hepatitis C: high alanine transaminase (ALT) serum levels (F = 14.04) and female gender (F = 5.03). At the univariate analysis, patients with autoantibodies had a more severe portal-periportal necroinflammation (median Scheuer's score: 2.05 vs. 1.64, P = .003). The presence of autoantibodies did not influence the response to interferon (IFN). In chronic hepatitis C, serum autoantibodies are common, but their subspecificities are distinct from those occurring in AIH. Whereas the absence of ANA-H and/or SMA-AA does not exclude AIH, the characterization of ANA and SMA may help to discriminate between the two conditions. As compared with the seronegative counterpart, autoantibody-positive chronic hepatitis C is more common in females and exhibits a more severe biochemical and histological activity. The response to IFN therapy, however, is similar.     

Clinical diagnosis in patients with smooth muscle antibodies. A study of a one-year material

Out of 17 109 sera tested for autoantibodies by indirect immunofluorescence, 236 contained smooth muscle antibodies (SMA) with a titre of greater than or equal to 1/25. The majority of these sera, from 190 patients, reacted both with smooth muscle and renal glomeruli and the specificity of these SMA is against actin. 91% of high-titred sera (greater than or equal to 1/100) with IgG antibodies giving this staining pattern were derived from patients with chronic inflammatory liver disease, mainly chronic active hepatitis. In the group with a titre of 1/25, non-liver diseases such as joint diseases were more common and liver conditions occurred only in 55%. Sera with SMA of IgM class weremostly derived from patients with acute viral hepatitis.     

One-step 2-minute test to detect typhoid-specific antibodies based on particle separation in tubes

Typhoid fever is caused by Salmonella typhi. Detection of anti-S. typhi antibodies in the patient is a useful diagnostic aid. Among the various methods developed over the years for this purpose, the Widal test, based on bacterial agglutination, has remained the most widely used, even though it is neither specific nor sensitive. Its popularity stems from the fact that it is simple to use and inexpensive. We describe a new test which also uses a simple one-step procedure but is more rapid and accurate than the Widal. The new test (TUBEX) detects anti-Salmonella O9 (both immunoglobulin M [IgM] and IgG) antibodies in patients by inhibiting the binding between an anti-O9 IgM monoclonal antibody (MAb) conjugated to colored latex particles and S. typhi lipopolysaccharide (LPS) conjugated to magnetic latex particles. The reactants are mixed in a specially designed microtube for 2 min, and the result is read based on the resultant color of the supernatant following forced sedimentation of the magnetic beads. In the absence of inhibitory antibodies, there is a color change (from blue to red) due to cosedimentation of the indicator particles with the magnetic particles, whereas if these antibodies are present, they prevent such a change to a degree dependent on their concentration. Preliminary examination of TUBEX using the anti-O9 MAb and irrelevant MAbs as inhibitors revealed the test to be specific and reproducible, with an analytical sensitivity of 16 micrograms per ml of antibody. The reagents remained stable for at least 9 months when kept at 4 degrees C. In the examination of 16 stored sera obtained from 14 patients with proven cases of typhoid fever and 78 serum samples from 75 subjects without typhoid fever, TUBEX was found to be 100% sensitive and 100% specific. The nontyphoid group comprised 26 healthy blood donors, 30 antinuclear antibody (ANA)-negative patients, 9 ANA-positive patients, of whom 1 was positive for anti-DNA antibody, 4 typhus patients, and 6 septicemic patients. In addition, the sera obtained from 11 patients clinically diagnosed as having typhoid fever were all positive in the test. The TUBEX results correlated to some extent, albeit insignificantly (r = 0.38, P = 0.07), with those of an enzyme-linked immunoassay (ELISA) which used a similar detection format (inhibition) and reagents (S. typhi LPS and anti-O9 antibody). TUBEX correlated very well with ELISAs which detected anti-S. typhi LPS IgM (r = 0.58, P = 0.003) or IgG (r = 0.54, P = 0.006) antibodies from the typhoid patients. There was no correlation with the Widal test. The TUBEX test, if performed on slides (instead of tubes) or with soluble antigen (instead of antigen-conjugated magnetic beads), suffered significantly in sensitivity. Direct agglutination tests using LPS-conjugated indicator particles performed either on slides or in microwells also failed to detect antibodies from the majority of typhoid patients. Thus, TUBEX appears to be well designed and well suited for use in the laboratory or by the bedside as a simple, rapid aid to the routine diagnosis of typhoid fever.     

Job-sharing: a recipe for success

Circulating antituberculous antibodies in the sera from 89 patients with pulmonary tuberculosis and 11 patients with tumors and nonspecific inflammation in the lungs were evaluated using indirect hemagglutination and enzyme immunoassay. Specific antibodies were detected in 81.6 and 30% of tuberculous and nontuberculous patients, respectively.