IgG subclasses of antibodies to type II collagen in rheumatoid arthritis differ from those in systemic lupus erythematosus and other connective tissue diseases

OBJECTIVE

To compare IgG subclass distribution of autoantibodies to native type II collagen in patients with rheumatoid arthritis (RA) and in other rheumatic and inflammatory diseases including systemic lupus erythematosus (SLE).

METHODS

The IgG subclass of antibodies to native type II collagen were measured by modified ELISA using chemiluminescent detection and subclass-specific monoclonal antibodies in sera that contained IgG antibodies to collagen using conventional ELISA.

RESULTS

Antibodies to native type II collagen were present in sera of 20% of 323 patients with RA. 9% of 211 patients with SLE, 12% of 50 patients with osteoarthritis, and 13% of 75 patients with other chronic inflammatory diseases, but the highest levels occurred in patients with RA. The IgG subclass distribution of these antibodies differed markedly according to disease. In RA the predominant subclasses were IgG1 (58%) and IgG3 (47%), whereas in SLE the predominant subclass was IgG4 (69%). IgG2 was represented across all disease groups. Overall the frequency of IgG1 and/or IgG3 antibodies to type II collagen (84%) was significantly greater in RA than in other disease groups combined (20%) (p < 0.0001).

CONCLUSION

Antibodies to native collagen in RA were predominantly of the complement fixing and potentially damaging subclasses IgG1 and IgG3, but in SLE were of the non-complement fixing subclass IgG4; in other diseases, where present, antibodies were mostly IgG2 and of low level. These observations support the importance of autoimmunity to collagen in the pathogenesis of RA.

Evaluation of ICA512As in combination with other islet cell autoantibodies at the onset of IDDM

OBJECTIVE

The ICA512 pancreatic islet autoantigen is a putative tyrosine phosphatase that is co-identified with the earlier described 40-kDa autoantigen. We report the frequency of autoantibodies to islet cell antigen 512 (ICA512As) in recent-onset IDDM and compare this with other islet cell autoantibodies, including those to GAD (GADAs), insulin (IAAs), and islet cell cytoplasm (ICAs) identified by immunofluorescence.

RESEARCH DESIGN AND METHODS

Sera from 232 children aged between 9 months and 14.9 years collected within 14 days of diagnosis were tested for ICA512As by a radioimmunoprecipitation assay. The results were compared with previously reported data for GADAs (n = 232), IAAs (n = 167), and ICAs (n = 230).

RESULTS

The frequency of a positive result for ICA512As in children with newly diagnosed IDDM was 60%. The frequency was greater for children with an age of onset between 5 and 10 years (69%) than for children aged < 5 years (49%) and aged between 10 and 15 years (56%). The frequencies for other autoantibody reactivities were 69% for GADAs, 65% for IAAs, and 70% for ICAs. A combination of positive results for ICA512As, GADAs, and IAAs gave a sensitivity for the diagnosis of childhood IDDM of 95%, which was not significantly increased by a positive result for ICAs (96%).

CONCLUSIONS

Our results further establish that positivity in a combination of tests is more valuable for the prediction of IDDM than a result for any single autoantibody and that the age of the patient should be considered when selecting the combination of tests to use.

Autoantibodies associated with presymptomatic insulin-dependent diabetes mellitus in women

Presymptomatic autoantibody markers of insulin-dependent (Type 1) diabetes mellitus (IDDM) are less well characterized in adults than in children. We quantitated anti-GAD, anti-ICA512 and ICA by titration to endpoint and compared frequencies and levels in 139 Finnish women from whom 390 serum samples had been archived during antecedent pregnancies for 10 years before and up to 1 year after diagnosis of diabetes. Also, we compared the autoantibody status in adults with IDDM with that of children with newly diagnosed IDDM. Of the 35 women seropositive for 1 or more autoantibodies, 77% developed IDDM, 11% non-insulin-dependent (Type 2) diabetes mellitus (NIDDM), 9% gestational diabetes mellitus requiring insulin (GDM-ins) and 3% GDM controlled by diet. The frequency of antibodies during the 10-year presymptomatic period was 83% for anti-glutamic acid decarboxylase (GAD), 52% for anti-ICA512 and 41% for islet cell antibodies (ICA) for those who developed IDDM, 25%, 17%, and 0% for NIDDM, 12%, 4%, and 8% for GDM-ins and 1%, 0%, and 1% for GDM-diet. Anti-GAD was found most consistently in early samples; 13 of 15 with a single autoantibody at their first test had anti-GAD. Among those who developed IDDM, the frequency of anti-GAD was constant, anti-ICA512 increased threefold, and ICA increased slightly before diagnosis. Levels of the autoantibodies varied between subjects, but were relatively stable in individual subjects. Comparison of tests on the women, and children after diagnosis of IDDM, showed the frequencies and levels to be the same for anti-GAD but lower for anti-ICA512 and ICA in adults. Our observations show in women the long latency of seropositivity before overt IDDM, the predominance of anti-GAD among these three serological markers, and the presence of these markers in NIDDM presumably representing a NIDDM phase of autoimmune insulitis.

High T cell responses to the glutamic acid decarboxylase (GAD) isoform 67 reflect a hyperimmune state that precedes the onset of insulin-dependent diabetes

Pancreatic islet beta-cell destruction leading to insulin-dependent diabetes mellitus (IDDM) is an autoimmune T cell-mediated process. Peripheral blood T cells, which proliferate to islet antigens such as glutamic acid decarboxylase (GAD), (pro)insulin or tyrosine phosphatase IA-2, can be detected in at-risk, first degree relatives of people with IDDM. However, cross-sectional studies cannot define the relationship between T cell responses and progression to IDDM. Longitudinal studies were therefore undertaken on 50 at-risk, first degree relatives tested at least yearly for up to 4 years, during which time five developed IDDM. Peripheral blood T cell responses to a GAD67(aa208-404)-glutathione-S-transferase (GST) fusion protein, GST, insulin and tetanus toxoid were measured, together with antibodies to islet cells, GAD, insulin and IA-2. High levels of antibodies to GAD or insulin were generally associated with low T cell responses to these antigens. Relatives who developed IDDM were characterized by high levels of antibodies to insulin and/or islet cells, and high T cell responses to GAD67-GST and tetanus, but not insulin, in the 24 months before clinical diagnosis. Cross-sectionally, T cell responses to GAD67(aa208-404)-GST and to full-length GAD65-GST were highly correlated (r=0.75, P<0.002). In conclusion, increased cellular immunity to the mid region of GAD67 was a marker of late pre-clinical IDDM, but appears to reflect a more general, transient state of cellular immune hyperresponsiveness.

Presence of antibodies to native G1 domain of aggrecan core protein in synovial fluids from patients with various joint diseases

OBJECTIVE

To investigate the occurrence of IgG antibodies to aggrecan in synovial fluids (SF) from patients with arthritis and various articular diseases, and to determine the nature of epitopes present within aggrecan that react with these antibodies.

METHODS

SF samples were reacted with native aggrecan, reduced and alkylated aggrecan, chondroitin sulfate, and keratan sulfate, using dot-blots and a novel enzyme-linked immunosorbent assay (ELISA). The nature of the epitopes present on aggrecan was elucidated using Western blots and a competitive inhibition ELISA.

RESULTS

IgG antibodies to aggrecan were found in > 50% of the SF samples tested. No IgG antibody reactivity was observed in serum from the same patients. The antibodies appeared to react predominantly with native aggrecan, and there was no disease specificity. It was shown that the epitopes to these antibodies were located within the N-terminal region of the core protein.

CONCLUSION

This study demonstrates the frequent occurrence of IgG antibodies to aggrecan in human SF. The major epitope is located in the G1 domain of the aggrecan core protein. These IgG antibodies appear to be produced locally within the synovial cavity, probably in response to various articular diseases, resulting in the loss of native aggrecan from articular cartilage.

Lack of autoimmune serological reactions in rodent models of insulin dependent diabetes mellitus

Spontaneous insulitis with insulin-dependent diabetes mellitus (IDDM) in rodent models, the BB rat and NOD mouse, has clarified the pathogenesis of and guided decisions on interventional therapy for human IDDM. However, the occurrence in such models of a standard marker of human IDDM, autoantibodies to beta islet cell constituents, has been controversial. Hence we assessed diabetes-prone rodents for the frequencies of raised levels of auto-antibodies to glutamic acid decarboxylase GAD (anti-GAD), insulin and heat shock protein 65 (HSP-65) in relation to levels in non-diabetes-prone animals and levels in human diabetic sera. Assays were performed sequentially at various ages of life. The immunoassays used for anti-GAD and anti-insulin were those validated for sensitivity and specificity for detection of the corresponding autoantibodies in human IDDM sera at international workshops. Positive controls included human IDDM sera with reactivity with GAD or insulin and, for mouse anti-GAD, the highly reactive monoclonal antibody, GAD-6. The results were that levels of autoantibodies in diabetes-prone BB rats or NOD mice to the "IDDM-relevant' autoantigens in our panel did not exceed levels in control rats or mice, and were much lower than levels in humans with IDDM. We conclude that the BB rat and NOD mouse represent a model, but not a facsimile, of human IDDM and that therapeutic successes in such models should be interpreted with caution in relation to interventional therapy for human IDDM.

Immunosusceptibility genes in rheumatoid arthritis

The polygenic predisposition to RA is conferred particularly by disease susceptibility sequences in the HVR3 of HLA DRB1 present in those subtypes of DR4 and DR1 that are associated with RA. The aim of this study was to examine predisposing interactions between genes encoding HLA and immunoglobulin molecules. Accordingly, we compared the genetic background of 114 Australian patients with RA with that of Australian controls of similar ethnic background. We identified HLA-A, B, and DR phenotypes serologically, HLA-DR, DQ alleles, and subtypes of DR4 by DNA typing, and Gm allogenotypes and immunoglobulin switch region polymorphisms by RFLP. For the subjects with RA, we confirmed previously reported observations that included an excess of females, 71%, a high frequency of HLA types DR4 or DR1 of 77% versus controls 47%, and a high frequency of the HVR3 susceptibility sequences of 76%, with 24% homozygous, and 52% heterozygous for the sequences. We observed other genetic correlations in RA that included increases in frequencies of DR4 in males, DR1 in females, the class I specificity HLA-B27 overall but more particularly in females, 24% in females, versus 5% of controls, HLA-DQB1*0302 (DQ8) in DR4*0401-positive patients, and the Gm allogenotype 1,2,3;23 +/- ; 5,10, 15% of patients versus 4% of controls. Examination of switch region genes gave no evidence of differences in the polymorphisms distributions. Thus, the major genetic risks for RA that are conferred by female gender and the HVR3 of HLA DRB1 are modulated by interactions between gender and HLA class I and class II alleles, and the Gm allogenotype.

Diabetic sera react with the glutamic acid decarboxylase molecule in a dimeric-oligomeric form

Glutamic acid decarboxylase (GAD) is a major autoantigen in insulin-dependent diabetes mellitus (IDDM). This was initially identified as a 64-65 kD molecule according to migration in gels after immunoprecipitation from pancreatic islets. We studied the antigenicity of two different radiolabelled preparations of GAD, derived either by affinity purification from porcine brain and known to contain GAD 65 and GAD 67, or by expression from a cDNA for human GAD 65 by rabbit reticulocyte lysate (RRL). Radiolabelled immunoprecipitated pellets from the reaction of potent antisera to GAD from patients with IDDM were examined by autoradiography after SDS-PAGE under reducing or non-reducing conditions. Also, preparations of porcine brain GAD were "depleted' of GAD by exposure to antisera, and then similarly re-examined. Autoradiography of radiolabelled GAD either affinity purified from porcine brain, or expressed by RRL, showed that the immunoprecipitated protein migrated under non-reducing conditions according to a M(r) of approximately 110-130 kD, corresponding to dimeric forms of monomeric GAD of approximately 55-65 kD. Depletion by immunoprecipitation of this minor higher M(r) component from preparations of GAD left, in the supernatant, an abundance of GAD of M(r) 64-65 kD corresponding to monomer that was completely non-reactive with potent IDDM sera. We conclude that IDDM sera react with the GAD molecule in a dimeric (or oligomeric) form. Our findings have general connotations for self-tolerance and autoimmunity.

Antibodies to type II collagen in early rheumatoid arthritis. Correlation with disease progression

OBJECTIVE

To establish that frequencies and levels of IgG antibodies to type II collagen are higher in early rheumatoid arthritis (RA), and to correlate these results with disease activity.

METHODS

Forty-four patients were characterized as having early RA. Patient sera obtained at initial presentation and at 12 months were tested by enzyme-linked immunosorbent assay for IgG antibodies to native and denatured type II collagen.

RESULTS

IgG antibodies to native and denatured type II collagen were detected at initial presentation in 27% and 82% of patients, respectively, and after 12 months in 14% and 50%, respectively. The presence of antibodies to native collagen was associated with activity of RA and severity of symptoms, and loss of antibodies at 12 months was associated with initially erosive RA and the DRB1 disease susceptibility motif.

CONCLUSION

Levels of serum IgG antibodies to collagen in RA decrease over time and, therefore, are not attributable simply to cartilage destruction. The presence of early positivity for these antibodies, together with the RA susceptibility motif, appears to be predictive of rapidly progressive RA.

Low prevalence of immunogenetic markers of IDDM in adult Koreans with diabetes detected on OGTT

In the Asian populations, it is not uncommon for adult patients with NIDDM to eventually lose beta-cell function and develop IDDM. Accepting that IDDM is an autoimmune disease, which occurs on a genetic background, it could by hypothesized that by measuring autoantibody prevalence and HLA DQ gene polymorphism, known important prediagnostic markers of IDDM, the prevalence of adult-onset IDDM in patients with previously undiagnosed NIDDM patients could be estimated. To do this, anti-GAD prevalence and HLA DQ A1 and DQ B1 polymorphisms after PCR amplification of genomic DNA were analyzed in 121 newly diagnosed diabetic patients of Yonchon cohort and compared to the results with those of 100 matched health control subjects. We also compared the results with those of other populations to assess the difference of genotype distribution. The overall prevalence of anti-GAD antibodies was 1.7% (2 of 121) in patients with previously undiagnosed NIDDM, whereas 1 of 100 controls had positive antibodies. Among those who were positive, their titer of antibodies to GAD were not high. No statistically significant differences in the distribution of either mean levels of anti-GAD or DQA1 and DQB1 alleles were found comparing NIDDM patients to controls. Interestingly, the frequency of DQB1*non-Asp-57 and DQA1*Arg-52 alleles in the Korean adult control population was similar to that of US Caucasians (DQB1*non-Asp-57: 0.431 vs. 0.475; DQA1*Arg-52: 0.492 vs. 0.463). The low prevalence of anti-GAD antibodies and HLA-DQA1 and DQB1 susceptibility alleles among recent-onset NIDDM patients, not different compared to controls suggests that diabetes in Korean adults is unlikely to have an autoimmune component to its pathogenesis.

Autoantibodies to M2 mitochondrial autoantigens in normal human sera by immunofluorescence and novel assays

Primary biliary cirrhosis (PBC) is characterized by the presence of antimitochondrial antibodies (anti-M2), directed against the E2 subunits of the 2-oxo-acid dehydrogenase complexes (2-OADC), chiefly pyruvate dehydrogenase complex (PDC-E2). We present here a detailed study, based on a large panel of normal sera, of the specificity of tests for anti-M2 by immunofluorescence and for anti-PDC by other assays for the diagnosis of PBC. The assays for anti-PDC included immunoblotting with bovine heart mitochondria, ELISA using recombinant PDC-E2 and an enzyme inhibition assay using purified porcine PDC. The positivity rates for normal sera were 0 (0/170), 2 (4/201), 1.5 (3/198) and 0% (0/186) for immunofluorescence, immunoblotting, ELISA and the enzyme inhibition assay, respectively. The seven positive reactions detected either by immunoblotting (n = 4) or ELISA (n = 3) were negative by the other three assays and in no instance did biochemical indices give any indication of chronic liver disease. Thus, as judged by reactivity with normal sera, the specificity of a positive test for the antibody to the major M2 autoantigen (PDC-E2) is 100% for immunofluorescence and the enzyme inhibition assay, 98% for immunoblotting and 98.5% for ELISA.

Islet cell antibodies and antibodies against glutamic acid decarboxylase in newly diagnosed adult-onset diabetes mellitus

This study aimed to determine the prevalence of antibodies against glutamic acid decarboxylase (anti-GAD) and islet cell antibodies (ICA) in relation to beta-cell function in adults newly-diagnosed with diabetes mellitus. beta-cell function was assessed in adults aged 25-70 years newly-diagnosed with diabetes mellitus (n = 84) and control subjects (n = 34) using a 1.6 MJ mixed meal test procedure. beta-cell function was evaluated by the true insulin (defined as immunoreactive insulin minus proinsulin) response to the mixed meal test. Subjects were classified on the basis of the area under the true insulin curve (normal 16830-107700 pmol min/I) and the sum of the 30 and 60 min incremental response (normal 285-3295 pmol/I). The prevalence of anti-GAD and ICA was determined using radioimmunoprecipitation and indirect immunofluorescence, respectively. Twelve (14%) of the study cohort were insulin deficient showing little or no true insulin release. Of the insulin deficient individuals, seven (58%) subjects were anti-GAD antibody positive, compared with eleven (15%) of the subjects without insulin deficiency (P < 0.001). Seven (58%) insulin deficient subjects were ICA positive, whereas only two (3%) non-insulin deficient subjects were ICA positive (P < 0.001). Eight (67%) of the insulin deficient individuals had anti-GAD or ICA, compared with twelve (17%) of those who were not insulin deficient (P < 0.001). The positive predictive values for insulin deficiency of anti-GAD and ICA were 39 and 78% respectively. The sensitivity of both antibodies for detecting insulin deficiency was 50%. The specificity for detecting insulin deficiency was 85% for anti-GAD and 97% for ICA. Positivity for both anti-GAD and ICA gave a specificity and positive predictive value for insulin deficiency of 99%, and a sensitivity of 50%. Nearly one in seven adults presenting with diabetes mellitus as a new diagnosis are insulin deficient using our criteria. Loss of beta-cell function in two thirds of individuals who are insulin deficient can be identified by anti-GAD and ICA. Early detection of these immune markers of beta-cell damage creates the potential for immune modulation to limit such damage.

Pancreatic beta cell function and antibodies to glutamic acid decarboxylase (anti-GAD) in Chinese patients with clinical diagnosis of insulin-dependent diabetes mellitus

Antibodies to glutamic acid decarboxylase (anti-GAD) and pancreatic beta cell secretory function were measured in 39 consecutive Chinese patients with a clinical diagnosis of insulin-dependent diabetes mellitus (IDDM) (19 males, mean +/- SD age. 37 +/- 15 years; body mass index (BMI), 22 +/- 4 kg/m2; mean duration of disease, 6.7 +/- 5.6 years). IDDM was defined on the basis of acute symptoms with heavy ketonuria (> 3+) or ketoacidosis at diagnosis, or requirement for continuous insulin treatment within one year of diagnosis. Insulin deficiency was defined as a post-glucagon stimulated plasma C-peptide concentration < or = 0.6 nmol/l. Overall, anti-GAD antibodies were positive (> 18 units) in 23% (n = 9) of these patients. Of the 39 patients, 29 (74%) were insulin deficient and 10 (26%) were non-insulin deficient. Anti-GAD antibodies were positive in 31% of the insulin-deficient patients but in none of the non-insulin-deficient group. Insulin deficiency and anti-GAD positivity were associated with younger age, earlier age of clinical onset and lower BMI. There were independent negative relationships between levels of anti-GAD antibodies and blood pressure and a positive relationship between insulin dosage and albuminuria. This study emphasises the difficulty in differentiating clinically between IDDM and NIDDM in Chinese patients. Despite the acute presentation, these patients had variable pancreatic beta cell secretory function. The varying duration of disease may partly explain the low prevalence of positive anti-GAD antibodies in these patients, but seems unlikely to explain fully the difference from Caucasian IDDM patients.

Immunoreactivity of antimitochondrial autoantibodies in Japanese patients with primary biliary cirrhosis

The incidence and prevalence of primary biliary cirrhosis show wide geographic differences. The frequency of this disease in Japan is lower than in Northern Europe. To elucidate the immunoreactivity of serum with enzymes of the 2-oxo-acid dehydrogenase complex (2-OADC) and the M2 mitochondrial antigenic complex in Japanese patients, we examined sera from 107 patients with primary biliary cirrhosis from three geographically different regions of Japan. The sera were assayed by immunofluorescence on frozen tissue sections, immunoblotting on bovine heart mitochondria and recombinant E2 subunit of branched chain oxo-acid dehydrogenase complex (BCOADC-E2), ELISA using recombinant E2 subunit of human pyruvate dehydrogenase complex (PDC-E2) and purified porcine 2-oxoglutarate dehydrogenase complex (OGDC), and enzyme inhibition assay using procine PDC and OGDC. Of the 107 sera, 95 (88%) reacted by immunofluorescence, 102 (95%) by immunoblotting with at least one of the M2 autoantigens, although only 78 (73%) reacted with PDC-E2; 72 (67%) by ELISA with PDC-E2; and 81 (76%) with PDC by the enzyme inhibition assay. Thus, the frequency of reactivity with PDC-E2 by all assays was lower for Japanese than the reported frequency for Caucasian patients with primary biliary cirrhosis, whereas the frequency of reactivity by immunoblotting and ELISA against 2-OADC enzymes other than PDC was relatively higher. The relative frequency of reactivity of autoantibodies to the M2 autoantigens was similar for the three different regions of Japan. The different autoantibody profiles for Japanese and Caucasian patients with primary biliary cirrhosis point to immunogenetic and environmental determinants of this disease, which should provide new insights into its autoimmune origins.

Comparative epitope mapping of antibodies to collagen in women with silicone breast implants, systemic lupus erythematosus and rheumatoid arthritis

Previous work has shown that women with silicone gel breast implants have an increased frequency of autoantibodies to collagen types I and II. 70 women without a specific autoimmune disease, using criteria of the American College of Rheumatology, but who had silicone breast implants were studied for the presence of serum antibodies to native and denatured human types I and II collagen by ELISA. 82 women with systemic lupus erythematosus (SLE), 94 women with rheumatoid arthritis (RA), and 133 healthy controls were also studied. There was a high frequency of autoantibodies to collagen in each of the groups when compared to the healthy controls. The specificities of these antibodies were found to differ markedly when examined by immunoblotting using peptides derived by cyanogen bromide digestion of the collagens. Sera from women with silicone implants reacted with multiple peptides of type I collagen in an individual-specific manner, but sera from women with SLE or RA reacted weakly with a restricted range of peptides. Against type II collagen, sera from women with RA reacted strongly with multiple peptides, while sera from women with silicone implants or SLE reacted only weakly or not at all. The patterns of reactivity against collagens by sera from women with silicone implants suggest that silicone can act as an adjuvant to enhance the immunogenicity of type I collagen.

Pancreatic islet cell cytoplasmic antibody in diabetes is represented by antibodies to islet cell antigen 512 and glutamic acid decarboxylase

The presence of serum islet cell cytoplasmic antibodies (ICAs) is a standard autoimmune marker for insulin-dependent diabetes mellitus (IDDM). The antigenic molecule(s) responsible for ICA has not been identified, although antibodies to the 65-kDa isoform of glutamic acid decarboxylase (GAD65) do contribute. We tested 129 IDDM sera for antibodies to ICA512 (anti-ICA512), antibodies to GAD (anti-GAD), and ICAs; we tested for inhibition of ICAs with purified recombinant ICA512 and sheep brain GAD; and we tested for immunofluorescence reactivity on COS7 cells transfected with cDNA clones encoding ICA512 and GAD65. The results were that anti-ICA512 antibodies contribute to ICA reactivity and that these, in combination with anti-GAD antibodies, account for most ICA reactivity in IDDM. Anti-ICA512 antibodies were present at a frequency of 51% in 61 patients with early-onset IDDM (age of onset < or = 20 years) of short duration (< or = 1 month) but only in 9% of 68 patients with an onset age of > 20 years and/or a disease duration of > 1 month. The frequency of anti-GAD antibodies in these sera was similar irrespective of duration or age of onset. Anti-ICA512 and anti-GAD antibodies were demonstrable by indirect immunofluorescence on transfected COS7 cells, and ICA could be inhibited using either recombinant ICA512 or purified brain GAD. We conclude that anti-ICA512 and anti-GAD antibodies contribute to ICA reactivity and that anti-ICA512 antibodies account for the increased frequency of ICA reactivity in early-onset IDDM of short duration.

Prevalence of antibodies to glutamic acid decarboxylase in women who have had gestational diabetes

OBJECTIVES

Our purpose was to determine the prevalence of autoantibodies to glutamic acid decarboxylase in women who had had gestational diabetes, including those in whom insulin-requiring or non-insulin-requiring diabetes mellitus has since developed.

STUDY DESIGN

The study group comprised 734 women with previous gestational diabetes who were consecutive attendees to a follow-up clinic. These women were tested for autoantibodies to glutamic acid decarboxylase with a radioimmunoprecipitation assay. We similarly tested 104 women in whom permanent diabetes mellitus developed after gestational diabetes, of whom 20 were using insulin and 84 were not. Those using insulin also had fasting C-peptide levels measured.

RESULTS

Thirteen of the 734 (1.8%, 95% confidence interval 0.9% to 3.0%) women with previous gestational diabetes were positive for autoantibodies to glutamic acid decarboxylase. Of the 20 women with diabetes treated with insulin, 12 had insulin deficiency confirmed by low levels of C peptide; all 12 were positive for autoantibodies to glutamic acid decarboxylase. Of the 84 women with diabetes not requiring insulin, 6 (7.1%, 95% confidence interval 2.7% to 14.9%) were positive for autoantibodies to glutamic acid decarboxylase.

CONCLUSIONS

The prevalence of autoantibodies to glutamic acid decarboxylase in women with previous gestational diabetes was 1.8%. Our data also showed that insulin-dependent diabetes mellitus will develop in 1.7% of women with gestational diabetes. A positive test for autoantibodies to glutamic acid decarboxylase may help in the early identification of insulin-dependent diabetes mellitus. Adult-onset insulin-dependent diabetes mellitus developed in only 5.2% (12/230) of women with previous gestational diabetes who later had diabetes mellitus.

Continuity of care by a midwife team versus routine care during pregnancy and birth: a randomised trial

OBJECTIVE

To compare continuity of care from a midwife team with routine care from a variety of doctors and midwives.

DESIGN

A stratified, randomised controlled trial.

PARTICIPANTS AND SETTING

814 women attending the antenatal clinic of a tertiary referral, university hospital.

INTERVENTION

Women were randomly allocated to team care from a team of six midwives, or routine care from a variety of doctors and midwives.

MAIN OUTCOME MEASURES

Antenatal, intrapartum and neonatal events; maternal satisfaction; and cost of treatment.

RESULTS

405 women were randomly allocated to team care and 409 to routine care; they delivered 385 and 386 babies, respectively. Team care women were more likely to attend antenatal classes (OR, 1.73; 95% CI, 1.23-2.42); less likely to use pethidine during labour (OR, 0.32; 95% CI, 0.22-0.46); and more likely to labour and deliver without intervention (OR, 1.73; 95% CI, 1.28-2.34). Babies of team care mothers received less neonatal resuscitation (OR, 0.59; 95% CI, 0.41-0.86), although there was no difference in Apgar scores at five minutes (OR, 0.86; 95% CI, 0.29-2.57). The stillbirth and neonatal death rate was the same for both groups of mothers with a singleton pregnancy (three deaths), but there were three deaths (birthweights of 600 g, 660 g, 1340 g) in twin pregnancies in the group receiving team care. Team care was rated better than routine care for all measures of maternal satisfaction. Team care meant a cost reduction of 4.5%.

CONCLUSION

Continuity of care provided by a small team of midwives resulted in a more satisfying birth experience at less cost than routine care and fewer adverse maternal and neonatal outcomes. Although a much larger study would be required to provide adequate power to detect rare outcomes, our study found that continuity of care by a midwife team was as safe as routine care.

Hepatic portal infiltrates in mice immunized with syngeneic lymphoid cells: connotations for models of autoimmune liver disease

The aim of this study was to investigate liver histology in mice after immunization with the conserved self molecule dihydrolipoamide dehydrogenase, E3, a subunit of the mitochondrial 2-OADC enzyme family identified as the M2 autoantigen in the liver disease, primary biliary cirrhosis. Mice were immunized by a novel procedure. The autoantigen E3 was introduced by pinocytosis into hypertonically treated syngeneic lymphoid cells to facilitate intracellular antigen processing and presentation and the generation of a cytolytic T cell response. Liver sections were examined and scored for evidence of an inflammatory response by two independent procedures: standard microscopy with visual scoring, and automated scanning with computerized scoring. There was a close correlation between read-outs of liver histology by standard microscopy and automated scanning, using the index of mononuclear cellular infiltrations in hepatic portal tracts. Such infiltrates were prominent in the immunized mice, but, unexpectedly, the degree of infiltration was similar in mice injected with autoantigen (E3)-loaded syngeneic cells, or syngeneic cells treated only with hypertonic medium. The equivalent changes in the liver with the experimental and control protocol is indicative of the reactivity of the liver to any provocative immune stimulus, and is cautionary for protocols designed for the induction of autoimmune liver disease in experimental animals.

Hypopigmented macules in acantholytic disorders

BACKGROUND

Widespread hypopigmented macules are rarely seen in heavily pigmented patients with Darier's disease. Previous hypotheses concerning the cause of decreased pigmentation suggest it is a postinflammatory phenomenon or that the hypomelanosis is evidence of subclinical acantholysis.

PATIENTS

This report presents 2 patients: a new case of disseminated guttate leukoderma in a black patient with Darier's disease and the first such case in a patient with transient acantholytic dermatosis (Grover's disease). Direct immunofluorescence and electron-microscopic studies were carried out on lesional biopsies.

OBSERVATIONS

Numerous small hypopigmented macules were observed in two black patients followed for acantholytic disorders. Three biopsies of the hypopigmented macules revealed acantholysis, while one showed only decreased melanin. Direct immunofluorescence studies were negative. Electron-microscopic studies of the leukodermic macules showed sparse melanocytes and melanosomes that were mostly pigmented stage IV melanosomes.

CONCLUSIONS

Disseminated guttate leukoderma can occur in transient acantholytic dermatosis, as well as in Darier's disease. It is readily apparent on darkly pigmented skin because of contrast. The etiology of this phenomenon is still unknown.

Antibody reactivity to mycobacterial 65 kDa heat shock protein: relevance to autoimmunity

Reactivity to the mycobacterial 65 kDa heat shock protein (HSP 65) has been implicated in the pathogenesis of adjuvant arthritis in the rat, and may be involved in the pathogenesis of rheumatoid arthritis or other autoimmune diseases in humans. Accordingly this study sought quantitative or qualitative differences in the antibody reactivity to HSP 65 between normal controls, patients with the multisystem autoimmune diseases, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) and patients with the mycobacterial infections, tuberculosis (TB) and leprosy. Levels of antibodies to recombinant HSP 65 in serum were measured by ELISA in normal subjects and in patients with RA, SLE, TB or leprosy. Antibody reactivity was examined by Western blotting using polypeptide fragments of HSP 65 derived by recombinant DNA techniques, or by digestion with trypsin or cyanogen bromide (CNBr). Reactivity to a synthetic peptide, the adjuvant arthritis T-cell epitope of HSP 65 (180-188), was tested by ELISA. High levels of antibodies to full length recombinant HSP 65 from Mycobacterium bovis were present in all the groups tested. By Western blot analysis, most reactivity with intact HSP 65 was retained in a 32 kDa tryptic fragment, judged by sequencing and size estimations to represent amino acid residues 118- approximately 388. This sequence included a major T-cell epitope for adjuvant arthritis (180-188), but these nine amino acids were not essential for B-cell reactivity since most sera also reacted with residues 188-540 which lack the T-cell epitope. Moreover, the 180-188 synthetic peptide was unreactive by ELISA, and did not inhibit reactivity with the intact recombinant HSP 65. In conclusion, most individuals had antibodies to mycobacterial HSP 65, presumably resulting from previous bacterial infections. The magnitude of the response was unrelated to the occurrence of systemic autoimmune disease, and the pattern of antibody reactivity with recombinant and proteolytic fragments of HSP 65 suggests that the major B-cell epitope is conformational and consists of discontinuous regions of the molecule.

Differing frequency of autoantibodies to glutamic acid decarboxylase among Koreans, Thais, and Australians with diabetes mellitus

The wide racial-geographic differences in the incidence and prevalence of insulin-dependent diabetes mellitus (IDDM) between Europids and Asian populations prompted us to compare frequencies of positivity of autoantibody to glutamic acid decarboxylase (GAD). The patients with IDDM included 41 Koreans, 30 Thais, and 45 Australian Europids; the Koreans included 14 cases regarded as atypical IDDM by reason of a delayed requirement for insulin treatment. Autoantibodies were measured by radioimmunoprecipitation using iodinated purified porcine brain GAD. The frequency of positive tests for anti-GAD of 30% (8/27) for Koreans and 51% (20/39) for Thais was significantly lower than the 84% (38/45) for Australian Europids, even after stratifying by age of onset. Correspondingly, the mean levels of anti-GAD among seropositive cases were significantly lower for Koreans than for Australian Europids. In contrast to Thais and Australians, more than half the Koreans were diagnosed at age > 20 years, but there was no significant difference in positivity for anti-GAD between those over or under the age of 20 at diagnosis. The different frequency of positivity in tests for anti-GAD among Koreans, Thais, and Australian Europids with IDDM suggests that there is a greater etiologic heterogeneity of IDDM among Asian than Europid populations, in whom autoimmune destruction of pancreatic islets predominates.

Antibodies to collagen: comparative epitope mapping in women with silicone breast implants, systemic lupus erythematosus and rheumatoid arthritis

Women with silicone breast implants have a significantly increased frequency of antibodies to collagen types I and II. To characterize the specificity of these antibodies, 70 women without a specific autoimmune disease, according to the criteria of the American College of Rheumatology, but who had silicone breast implants were studied for the presence of serum antibodies to native and denatured human types I and II collagen by ELISA. Positive sera were further studied by immunoblotting using peptides derived by cyanogen bromide digestion of the collagens. Samples of 82 women with systemic lupus erythematosus (SLE), 94 women with rheumatoid arthritis (RA), and 133 healthy controls were studied concurrently. There was a high frequency of autoantibodies to collagen in each of the study groups when compared to the healthy controls. However, and of particular interest, the epitope specificity of the autoantibodies differed markedly. Sera from women with silicone implants reacted strongly in an individual-specific manner with multiple peptides of type I collagen, whereas sera from women with SLE and RA reacted only weekly with a restricted range of peptides of type I collagen. Sera from women with RA reacted strongly with multiple peptides of type II, whereas sera from women with silicone implants or SLE reacted only weakly. The reactivity of women with silicone implants suggests that silicone or its biodegradation products can act as adjuvants in situ to enhance the immunogenicity of type I collagen, or protein-silicone conjugates.

Autoantibodies to glutamic acid decarboxylase and insulin in islet cell antibody positive presymptomatic type 1 diabetes mellitus: frequency and segregation by age and gender

The frequency of antibodies to glutamic acid decarboxylase (GAD) and insulin (IAA) in presymptomatic Type 1 diabetes mellitus with a positive test for antibodies to islet cell antigen (ICA) was examined. Thirty-two persons positive for ICA (> 10 JDF units) were tested 2 to 48 months before their ascertained onset of Type 1 diabetes. ICA was quantitated by immunofluorescence as JDF units, anti-GAD by radioimmunoprecipitation and anti-insulin by radioimmunoassay. There was a positive test for anti-GAD in 25 (78%), and for IAA in 23 (72%), of the 32 prediabetic ICA-positive subjects. Stratification according to age at the onset of diabetes showed differing frequencies of anti-GAD and IAA in the prediabetic stage. Thus the positivity rate for anti-GAD for 18 subjects older than 10 years at onset of diabetes was 83%, and for 14 aged 10 or younger at onset was 71%; conversely, the rate for IAA for 18 subjects older than 10 at onset was 56% and for 14 aged 10 or less at time of onset was 93% (p = 0.01). The frequency of anti-GAD was higher in females (88%) than males (71%) whereas the frequency of IAA was higher in males (82%) than in females (60%). Since autoantibodies to GAD and insulin occur in presymptomatic Type 1 diabetes with differences in frequencies by age and gender, the stimuli to autoimmunity may operate differently at different ages, and may also be gender-related.

Enzyme inhibitory autoantibodies to pyruvate dehydrogenase complex in primary biliary cirrhosis: applications of a semiautomated assay

Sera from patients with primary biliary cirrhosis inhibit the activity of the mitochondrial pyruvate dehydrogenase complex. We utilized this effect to develop a simple, miniaturized, semiautomated spectrophotometric assay as a diagnostic aid. The sera studied were from 71 patients with primary biliary cirrhosis and 62 other subjects. The assays included enzyme inhibition, immunofluorescence on HEp-2 cells, enzyme-linked immunosorbent assay using recombinant pyruvate dehydrogenase complex-E2 and immunoblotting on bovine heart mitochondria. With the 71 primary biliary cirrhosis sera, on which M2 antibody was detected by immunofluorescence in 64 (90%), antibodies against pyruvate dehydrogenase complex were detected in 53 (83%) by means of enzyme inhibition, in 57 (89%) by means of enzyme-linked immunosorbent assay and in 60 (94%) by means of immunoblotting. Of the 64 sera positive by immunofluorescence, 60 reacted with pyruvate dehydrogenase complex-E2 on immunoblotting, and the miniaturized enzyme inhibition assay was positive in 53 of these. The enzyme inhibition assay and enzyme-linked immunosorbent assay were calibrated to give a specificity of 100%. At this level, the sensitivities for detection of pyruvate dehydrogenase complex antibody were 83% and 87%, respectively. We found no significant changes in levels of reactivity with the enzyme inhibition assay or enzyme-linked immunosorbent assay according to disease stage. Treatment with cyclosporine was accompanied by a significant decrease in levels of antibody to pyruvate dehydrogenase complex-E2 that matched improved indexes of biochemical liver function.(ABSTRACT TRUNCATED AT 250 WORDS)