M. Viander

International recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies

Anti-nuclear antibodies (ANA) are fundamental for the diagnosis of autoimmune diseases, and have been determined by indirect immunofluorescence assay (IIFA) for decades. As the demand for ANA testing increased, alternative techniques were developed challenging the classic IIFA. These alternative platforms differ in their antigen profiles, sensitivity and specificity, raising uncertainties regarding standardisation and interpretation of incongruent results. Therefore, an international group of experts has created recommendations for ANA testing by different methods. Two groups of experts participated in this initiative. The European autoimmunity standardization initiative representing 15 European countries and the International Union of Immunologic Societies/World Health Organization/Arthritis Foundation/Centers for Disease Control and Prevention autoantibody standardising committee. A three-step process followed by a Delphi exercise with closed voting was applied. Twenty-five recommendations for determining ANA (1–13), anti-double stranded DNA antibodies (14–18), specific antibodies (19–23) and validation of methods (24–25) were created. Significant differences between experts were observed regarding recommendations 24–25 (p<0.03). Here, we formulated recommendations for the assessment and interpretation of ANA and associated antibodies. Notably, the roles of IIFA as a reference method, and the importance of defining nuclear and cytoplasmic staining, were emphasised, while the need to incorporate alternative automated methods was acknowledged. Various approaches to overcome discrepancies between methods were suggested of which an improved bench-to-bedside communication is of the utmost importance. These recommendations are based on current knowledge and can enable harmonisation of local algorithms for testing and evaluation of ANA and related autoantibodies. Last but not least, new more appropriate terminologies have been suggested.

IgA ANTIGLIADIN ANTIBODIES: A MARKER OF MUCOSAL DAMAGE IN CHILDHOOD COELIAC DISEASE

Antigliadin antibodies in serum samples of 31 children with coeliac disease were measured by an enzyme-linked immunosorbent technique. In young patients (less than 2 years) tested before gluten withdrawal IgA antigliadin antibody levels were invariably above the levels of 36 controls. The titres fell rapidly when gluten was eliminated from the diet and rose on its reintroduction. The titres were not always greater than the control level in older untreated patients. IgA antigliadin antibodies seem to be a good marker of the immune reaction in the jejunum triggered by gluten. In 2 IgA-deficient patients gluten challenge caused an increase in IgM antigliadin antibodies, and at the same time the number of IgM-containing cells increased in the jejunal mucosa. Rising IgG antigliadin antibody levels after gluten elimination were seen in 6 patients, 5 of whom had very low complement C3 levels before gluten elimination.

Serological markers and HLA genes among healthy first-degree relatives of patients with coeliac disease

Coeliac disease may remain undiagnosed because of the non-specific nature of the presenting symptoms. Several antibody tests are claimed as markers for this condition but a direct comparison of the available tests has not been reported. The probands and healthy first-degree relatives of 42 families with coeliac disease were studied. Histological examination of biopsy specimens revealed jejunal mucosal villous atrophy compatible with coeliac disease in 13 of 122 relatives. Reticulin-antibody-positive relatives with or without jejunal mucosal atrophy were genetically similar to the probands of the families (DR3 gene frequencies 55.3%-60.0%). Gliadin-antibody-positive relatives with normal mucosa were genetically different from the probands (DR3 gene frequency 16.7% versus 55.3%). IgA reticulin and endomysium antibodies detected 92.3% of subjects with silent coeliac disease. The only case that was missed had selective IgA deficiency and was positive for IgG-class reticulin antibodies. By contrast, gliadin antibodies detected only half of the cases. Follow-up of the 7 reticulin-antibody-positive relatives with normal mucosa revealed 2 further cases of coeliac disease and 1 of dermatitis herpetiformis during the next three years. Our family study shows that healthy reticulin-antibody-positive first-degree relatives of coeliac disease patients, irrespective of the state of the jejunal mucosa, are genetically similar to known coeliac disease patients. Reticulin-antibody positivity is an indicator of both silent and latent coeliac disease.

Candida albicans and atopic dermatitis

The role of sensitization and exposure to Candida albicans in atopic dermatitis (AD) was studied with skin‐prick tests, yeast cultures and immunoblotting in 156 young adults with AD attending the Department of Dermatology, University of Turku, during 1983–89. Eighteen patients with allergic rhinitis without eczema and 39 non‐atopics were included as controls. Parameters associated with severe AD were simultaneous anti‐C. albicans IgE and saprophytic C. albicans growth. A statistically significant correlation between C. albicans sensitization (specific IgE antibodies) and AD symptoms was observed only in patients with saprophytic C. albicans exposure. No correlation between C. albicans‐specific IgE and AD severity was shown in patients without gastrointestinal growth. Furthermore, severe eczema was seldom seen in patients without saprophytic C. albicans growth. The most important IgE‐binding components of C. albicans in immunoblotting were 27 and 46 kD proteins and mannan, a polysaccharide. IgG and IgA antibodies to C. albicans, mainly towards C. albicans mannan, were found in practically all 70 sera studied. These results suggest a continuous exposure and induction of IgE antibodies by C. albicans in AD patients. Severe phases of AD in colonized patients are associated with IgE synthesis against C. albicans. These findings suggest a role for C. albicans in the exacerbations of AD but the clarification of this subject needs double‐blind placebo‐controlled treatment trials.

Fate of Five Celiac Disease-Associated Antibodies During Normal Diet in Genetically At-Risk Children Observed from Birth in a Natural History Study

OBJECTIVES: To explore the natural history of antibodies against tissue transglutaminase (TGA), endomysium (EMA), reticulin (ARA), and gliadin (AGA-IgG and AGA-IgA) in children carrying HLA-conferred risk for celiac disease (CD) and observed frequently from birth.METHODS: TGA was measured in serum samples obtained between years 2000 and 2003 from 1,320 children carrying genetic CD risk. If a sample was TGA positive, all five antibodies were analyzed in all banked and forthcoming samples from that child, and a duodenal biopsy was recommended. At the end of this observation, in August 2004, the age of the children was from 1 to 9.5 yr (mean 4.1 yr).RESULTS: Forty-nine children (3.7%) were TGA positive. In these children, AGA-IgG had emerged at the mean age (± SD, range) of 2.0 ± 1.5, 0.5–6.6 yr, while TGA, EMA, and ARA all emerged concurrently somewhat later (TGA at 3.2 ± 1.5, 1.0–7.0 yr, P < 0.001 when compared to AGA-IgG). Despite continuing gluten exposure, positive TGA, EMA, ARA, AGA-IgA, and AGA-IgG values were spontaneously lost in 49%, 45%, 43%, 41%, and 32% of the children, respectively. CD was diagnosed by biopsy in 20 of the 26 TGA-positive children who consented to a biopsy.CONCLUSIONS: Potential CD trigger(s) other than only gluten probably function before AGA-IgG emerges, i.e., ≥3 months earlier than the transglutaminase-associated antibodies appear. In a remarkable proportion of the children, antibodies disappear spontaneously suggesting that regulatory immune phenomena under favorable circumstances are able to extinguish incipient CD in genetically at-risk children even without exclusion of gluten from the diet.

Natural history of transglutaminase autoantibodies and mucosal changes in children carrying HLA-conferred celiac disease susceptibility.

OBJECTIVE The natural history of the appearance and fate of transglutaminase autoantibodies (TGAs) and mucosal changes in children carrying HLA-conferred celiac disease (CD) risk remains obscure. The aim of this study was to investigate the sequence of events leading to overt CD by retrospective analysis of TGA values in serum samples collected frequently from genetically susceptible children since birth or early childhood. MATERIAL AND METHODS A total of 1101 at-risk children were recruited in the study. A duodenal biopsy was recommended to all TGA-positive children and performed if parental consent was obtained. RESULTS During up to 8 years of follow-up, 35 of the cohort children developed TGAs, the youngest at age 1.3 years. After age 1.3 years the annual TGA seroconversion rate was constantly around 1% at least until age 6 years. However, 18 of the 35 TGA-positive children (51%) lost TGAs, without any dietary manipulation. A further 7 children were IgA deficient; of these children, 2 developed IgG antigliadin antibodies (IgG-AGA). Only 13 of the 21 children (62%) who had duodenal biopsies had villous atrophy. The time that passed since emergence of TGAs failed to predict the biopsy findings. Only one of the children with TGAs and both of the IgA-deficient children with IgG-AGA had noticeable abdominal symptoms. CONCLUSIONS TGAs appear in children at a constant rate after 1 year of age until at least the age of 6 years. Over half of the children loose TGA without gluten exclusion, challenging TGA positivity-based CD prevalence estimates. In symptom-free children, a requirement of two consecutive TGA-positive samples taken >or=3 months apart before performing a duodenal biopsy might diminish the number of unnecessary intestinal biopsies.

Circulating IgA- and IgG-class antigliadin antibodies in dermatitis herpetiformis detected by enzyme-linked immunosorbent assay

SummaryA sensitive and technically simple enzymelinked immunosorbent assay (ELISA) was developed to demonstrate circulating IgA- and IgG-class antibodies to gliadin, a component of wheat gluten. Serum samples from 24 patients with dermatitis herpetiformis (DH), 5 with coeliac disease (CD) and 75 normal controls were analysed. Antigliadin antibodies (AGA) of the IgA class were detected in 71% of DH patients, all of the CD patients and 19% of the controls. IgG-AGA was found in over 90% of DH patients and controls and in all of the CD patients. The mean ELISA values of both IgA- and IgG-class AGA were significantly higher in DH patients than in the controls. The occurrence of circulating IgA-class AGA is compatible with the hypothesis that these antibodies can be deposited in the skin, e.g. as immune complexes, or due to cross-reactivity of gliadin and dermal reticulin.

IgE-, IgA- and IgG-antibody responses to carbohydrate and protein antigens of Candida albicans in asthmatic children

Analysis of IgE, IgA and IgG antibodies directed against Candida albicans antigens in 28 asthmatic children was performed with immunoblotting after SDS‐PAGE. Analysis with the purified eytoplasmic protein fraction revealed a major protein allergen with an MW of 46 kD. In addition to the major allergen, 15 other antigenic bands with molecular weights between 16 and 135 kD bound IgE. Ten of 13 anti‐C. albicans IgE‐positive children had IgE towards the 46 kD major allergen. None of the subjects in the study group or in the non‐atopic controls had IgA or IgG antibodies towards this protein. Analysis of the crude surface extract showed that mannan, a carbohydrate, was an intermediate allergen contrary to being the major antigen in IgA and IgG antibody responses.

Rheumatic Complaints as a Presenting Symptom in Patients with Coeliac Disease

Twenty-three cases of coeliac disease were found after a small bowel biopsy had been carried out on seventy patients with various rheumatic complaints. The prevalence of coeliac disease in patients with rheumatic disorders was estimated to be 1 in 243. The majority (19) of these cases were found by screening patient sera with a reticulin antibody test. Sjögrens syndrome was the most frequent rheumatic diagnosis, with a total of six cases. Coeliac disease may occur concomitantly with various rheumatic complaints, and serological screening is advisable.

IgE, IgA and IgG antibodies and delayed skin response towards Candida albicans antigens in atopics with and without saprophytic growth.

Immunoblotting and RAST were used to analyse IgE, IgA and IgG responses to antigens of Candida albicans. These were compared with the delayed skin response and C. albicans carriage in 40 atopic subjects. The majority of the atopic patients showed a strong IgG and IgA antibody response towards mannan, a carbohydrate, but only occasionally to proteins. Altogether 22 of the 40 patients showed specific IgE towards C. albicans by immunoblotting. The IgE response was mainly towards proteins, particularly to ones with molecular weights of 29 kD and 46 kD, and only in eight out of 22 IgE‐positive subjects towards mannan. The IgG and IgA responses to mannan and the total IgE response towards C. albicans assessed by RAST showed an association with C. albicans carriage, whereas the delayed skin response showed an inverse relationship. The immunological parameters characteristic of C. albicans carriage were found to be C. albicans‐specific depressed delayed skin response and elevated IgE, IgA and IgG responses. This situation in the atopies presenting such parameters may favour simultaneous sensitization and exposure by colonization. The degree of sensitization may be sufficiently high to produce symptomatic allergy, such as asthma, in some individuals during occasional overgrowth of C. albicans, e.g. due to antibiotic therapy.