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D J Unsworth

Publications and source records attributed to D J Unsworth.

At least 19 recordsLinked to original sources
PubMed1999

Evaluation of a high-throughput second antibody radiobinding assay for measuring IgA antibodies to human tissue transglutaminase.

We describe a novel high-throughput radiobinding assay for IgA antibodies to tissue transglutaminase (TG) which uses second antibody precipitation to isolate immune complexes. Using this assay, 24 of 25 patients with untreated coeliac disease (96%) and nine of 526 healthy blood donors (2%) had TG antibody levels above a threshold defined by the 97.5th centile of 347 schoolchildren. All patients and five of the nine blood donors with transglutaminase antibodies above this threshold were endomysial antibody (EMA) positive. Using this threshold, 410/445 (92%) routine clinical samples were concordant for TG antibodies and EMA, including 72 of 75 with EMA. TG antibodies above the 97.5th centile were found in 32 of 370 EMA negative samples, 15 of whom had anti-gliadin antibodies (AGA), histologically proven coeliac disease or partial villous atrophy. We conclude that this assay achieves a sensitivity and a specificity at least equivalent to those of EMA. It is technically simple and suitable for coeliac disease screening.

Adolescent↗
PubMed1999

Anti-tissue transglutaminase, anti-endomysium and anti-R1-reticulin autoantibodies-the antibody trinity of coeliac disease.

Anti-tissue transglutaminase has been recently described as the predominant autoantigen in coeliac disease. We purified serum anti-tissue transglutaminase antibodies from three patients with coeliac disease by column chromatography and eluted tissue section-bound R1-anti-reticulin antibodies from sections of rat tissue for two of these. Lastly, we generated seven mouse MoAbs to guinea pig tissue transglutaminase. Each preparation was examined for anti-tissue transglutaminase, anti-endomysium, anti-R1 reticulin and anti-gliadin antibodies. Column-purified patient antibodies and 2/7 mouse MoAbs gave characteristic anti-endomysium/anti-R1 reticulin reactivity on rat, monkey and human tissue. All positive sera gave indistinguishable patterns of immunofluorescence on rat liver, kidney and stomach, monkey oesophagus, and human umbilical cord. Anti-R1-reticulin eluted from sections showed anti-tissue transglutaminase reactivity in 2/2 cases, but 0/2 showed anti-gliadin reactivity. In both, tissue section-eluted anti-R1 reticulin gave endomysial staining on monkey oesophagus. None of the mouse monoclonals, or any of the purified patient's anti-tissue transglutaminase or anti-R1-reticulin antibody showed any reactivity with gliadin. These data confirm tissue transglutaminase as the predominant autoantigen in coeliac disease and suggest that both anti-endomysium and anti-R1 reticulin reactivities seen in coeliac disease arise due to an immune response to tissue transglutaminase. Rigorous immunoabsorption was sufficient to abrogate reactivity in the tissue transglutaminase ELISA, but failed to completely absorb anti-endomysium and anti-reticulin activity. The possibility remains that some of the anti-endomysium and anti-reticulin activity was directed against antigens other than tissue transglutaminase.

Adult↗
PubMed1999

Identifying immunoglobulin-A--deficient children and adults does not necessarily help the serologic diagnosis of coeliac disease.

BACKGROUND: Immunoglobulin A deficiency is more common in patients with coeliac disease and also in patients with other gastrointestinal diseases than in normal people. There is a concern, therefore, that routine serum immunoglobulin (Ig) A testing of all cases of suspected coeliac disease may lead to unnecessary biopsy. METHODS: Four hundred eighty-two routine consecutive samples from cases of suspected coeliac disease or malabsorption (109 children) were tested for IgA anti-endomysium and total IgA. Four hundred twenty-four sera samples also had IgG antigliadin checked for high-titre antibody. Archived adult sera from 31 patients with coeliac disease and 52 disease control subjects were included in the study. RESULTS: Seven routine cases with serum IgA less than 15% of the mean normal for age and four cases with undetectable IgA were identified. Four patients, including three of four with clear deficiency, underwent small bowel biopsy, and all four had normal histologic findings and normal intraepithelial lymphocyte counts. Only one of the seven had high-titre IgG antigliadin antibody but that patient had normal histologic findings. One (3%) of 31 adults with established coeliac disease and 1 (2%) of 52 control subjects were IgA deficient. CONCLUSIONS: Of patients with IgA deficiency, only those with both IgA deficiency and high-titre IgG antigliadin antibody should be routinely considered for biopsy.

Adult↗
PubMed1999

IgA anti-tissue transglutaminase as a diagnostic marker of gluten sensitive enteropathy.

AIMS: To compare and contrast the sensitivity, specificity, and positive predictive values of IgA antibodies to guinea pig tissue transglutaminase (ELISA), endomysium, and reticulin (immunofluorescence), and gliadin (ELISA), and IgG antibodies to gliadin and tissue transglutaminase. METHODS: Sera from 27 newly diagnosed patients with coeliac disease, 65 biopsied gastrointestinal disease controls, and 50 consecutive blood donors were tested. All cases were adults. RESULTS: IgA anti-tissue transglutaminase showed a sensitivity of 85% (23/27 coeliac disease cases seropositive), specificity 97% (2/65 controls and one blood donor showing low titre positivity), and a positive predictive value of 92%. High titre anti-tissue transglutaminase was only seen in coeliac disease. Disease controls with mucosal damage unrelated to gluten enteropathy were IgA anti-tissue transglutaminase negative. Sensitivity, specificity, and positive predictive values for IgA anti-endomysial antibody (monkey oesophagus) were 100%, 100%, and 100%, respectively, and for IgA anti-gliadin, 93%, 95%, and 89%, respectively. CONCLUSIONS: Tissue transglutaminase is a major autoantigen in coeliac disease. IgA (but not IgG) anti-tissue transglutaminase, especially when in high titre, is closely associated with coeliac disease, but low titres may not be disease specific. In this small pilot study, the established IgA anti-endomysial assay was the superior test.

Adult↗
PubMed1998

A practical approach to the use of intravenous immunoglobulin in neurological disease.

Intravenous immunoglobulin is now used in a wide range of neurological conditions. However, side effects are relatively common, treatment is expensive and sustained benefit unusual without repeated administration. This article aims to provide clinicians with an overview of the potential benefits and drawbacks of intravenous immunoglobulin in neurological practice and concludes with suggested guidelines for its use in adults.

Adjuvants, Immunologic↗
PubMed1995

Failure of intradermal skin testing with gluten to produce delayed hypersensitivity reactions in patients with dermatitis herpetiformis.

Dermatitis herpetiformis (DH) is characterized by a rash and a gluten-sensitive enteropathy (GSE) indistinguishable from that of coeliac disease. T-cell-mediated mechanisms have been implicated in the pathogenesis of GSE. It seems feasible that intradermal injection of gluten, in patients known to have GSE, could lead to an influx of T cells sensitized to gluten, with subsequent development of a delayed hypersensitivity-type reaction. Six patients with DH and three normal subjects had intradermal injections of 'Frazer's fraction III' (FFIII; the partial peptic tryptic digest of gluten which is known to be antigenic) and phosphate-buffered saline (PBS) as a control. Skin biopsies were taken at PBS and FFIII injection sites at 48 h. In addition, two of the patients with DH had biopsies taken of FFIII injection sites at 6 h. Monoclonal antibodies and the avidin-biotin-peroxidase technique were used to stain for T cells in the skin biopsies. A monoclonal antibody to a neoepitope exposed in the terminal complement complex and an immunofluorescent method were used to detect the presence of terminal complement component in biopsies taken from two of the control subjects and two of the patients. Both patients and control subjects developed a weal and flare within a few minutes of injecting the FFIII, and this persisted for up to 6 h. No skin reaction was present in either the patients or the control subjects at 48 h. No skin reaction was visible at any time following injection of PBS.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1995

DNA polymorphisms of the complement C6 and C7 genes.

The linked C6 and C7 loci are rich in genetic markers, both at the protein and DNA levels. There are now seven common DNA polymorphisms distributed over about 300 kbp of chromosome 5p12-14. We report a new TaqI RFLP for C7 and a method for typing a C7 variant (T368S) hitherto known only from cDNA clones. We have re-investigated the published RFLPs to provide information on their frequency in North European Caucasian (predominantly British and Irish) subjects and have revised some of the published parameters, especially the sizes of polymorphic restriction fragments. Their precise locations within the genes are also reported: the three markers for C6 are in exon 3, intron 3 and adjacent to exon 17 and the four markers for C7 are in introns 15 and 13 and in exons 13 and 9. The gene frequencies of the second commonest allele of all seven markers lie in the range 0.2 to 0.37, except C6 A/B in the Japanese, where the frequencies of both common alleles are about 0.45. We have estimated the gene frequencies for the DNA polymorphisms which correlate with C7 M/N phenotype and for the C6 A/B phenotype and find them to be the same as the phenotypic estimates in Caucasians and in the Japanese respectively. The markers provide the possibility of defining 128 haplotypes, many (28) of which have been observed. Allelic associations in these genes are generally surprisingly weak.

Alleles↗
PubMed1994

Serological screening suggests that adult coeliac disease is underdiagnosed in the UK and increases the incidence by up to 12%.

Because coeliac disease often presents atypically it is underdiagnosed. It is suggested that the detection rate may be increased by 12% if serology is used to identify cases of occult enteropathy. All adults noted incidentally to be R1 anti-reticulin antibody (ARA) positive in the course of routine autoantibody testing of 6532 sera over one year were followed. None of the eight patients with seropositive serum was suspected of having coeliac disease. All eight had high titres of IgA anti-gliadin and IgA anti-endomysial antibodies, neither of which is detected in a routine autoantibody test, in addition to IgA R1-ARA. On clinical review coeliac disease was considered probable in only one patient, but because of the strong serological evidence of gluten sensitivity, jejunal biopsy was advised in all eight. Seven agreed and all had villous atrophy and crypt hyperplasia in keeping with coeliac disease. Six of the seven presented initially with vague symptoms such as tiredness or arthralgia. These symptoms disappeared after several weeks of gluten withdrawal. Forty two sera showing reticulin staining patterns other than R1 were used as controls. Low titre IgA anti-gliadin was noted in two of 42 but none had IgA anti-endomysial antibody. These 42 cases were not recommended for biopsy. During our study 58 other new adult cases of coeliac disease were diagnosed, primarily on clinical rather than serological grounds, at the four hospitals that request autoantibody studies. Occult coeliac disease detected serologically thus increased the overall incidence of coeliac disease by 12% from 58 to 65 cases. R1-ARA, even in the absence of the expected symptoms and signs of coeliac disease, is an indication for jejunal biopsy and is a reliable indicator of occult coeliac disease.

Adolescent↗
PubMed1993

Defective IgG2 response to Pneumovax in HIV seropositive patients.

OBJECTIVE: To determine whether HIV (Human Immunodeficiency Virus) antibody positive adults are capable of mounting an effective immune response when immunized with polyvalent pneumococcal vaccine. DESIGN: 28 patients (nine homosexual men, one bisexual man, three heterosexual females, 10 injecting drug abusers, five haemophiliacs) and 11 healthy volunteers, were immunised with Pneumovax II and titres of IgG1 and IgG2 specific antibody measured before and 1 month after immunisation. Magnitude of immune response was related to CD4 T-lymphocyte count at time of immunisation to establish whether responses are better in early disease. MAIN OUTCOME MEASURES: Based on our data in healthy volunteers we defined an adequate response to Pneumovax II as a post immunisation IgG2 antibody level at least 50% greater than the pre immunisation level. RESULTS: The magnitude of the response was significantly higher in the normal volunteers (U = 95; p = 0.0328). Adequate IgG2 responses were seen in 11/11 normals but in only 14/28 HIV seropositives (chi 2 = 8.58; p < 0.01). Poor responses were unrelated to the CD4 T-lymphocyte count at immunisation. Absolute IgG2 deficiency accounted for the poor response in only 1 HIV patient. CONCLUSION: 50% of HIV antibody seropositive individuals fail to mount adequate immune responses to polyvalent pneumococcal vaccine. Non responders are unlikely to be protected.

Adult↗