Coeliac disease (CD), traditionally perceived as a rare childhood condition presenting with malabsorption, is instead an autoimmune multisystem disorder usually presenting in adulthood, affecting ⩾1% of the population and linked to the genetic expression of human leucocyte antigens (HLA) DQ2 and DQ8. Presentation occurs most often in the 40–60 years age-group, but potentially at any age. Symptoms attributable to the gut or to malabsorption may be mild, non-specific or absent; under one-third of patients have diarrhoea and almost half are overweight. Histological diagnosis no longer requires small intestine villous atrophy. The Marsh classification recognizes increased intraepithelial lymphocytes and crypt hyperplasia with intact villi as part of the gluten enteropathy spectrum, while some individuals have more subtle abnormalities identified only on electron microscopy. Serological testing for CD autoantibodies (to endomysium and tissue transglutaminase) has revolutionized diagnosis, shifting the process towards primary care. However, a substantial number of patients with CD are seronegative, particularly those without villous atrophy. The autoantibody to endomysium may be produced before histological change. The immune response to transglutaminase is crucial to the disease process. An exciting new development is the link between antibodies to organ-specific transglutaminases and clinical presentation; transglutaminases 2 (gut), 3 (skin) and 6 (nervous system). Negative testing for CD does not preclude its development later and HLA testing may allow ‘once and for all’ exclusion. In conclusion, an increasing proportion of patients with CD do not meet the ‘classic’ picture of malabsorption, positive serological testing and villous atrophy. Insisting on all these criteria for diagnosis will result in under diagnosis.

Praziquantel is widely used for treatment of schistosomiasis. Elimination of intravascular worms involves a combination of drug-induced changes at the worm surface and a host immune response against exposed parasite components. Loss of spines is a typical feature of schistosomes obtained from praziquantel-treated infected animals. The mechanism for this is unknown. We have considered the possibility that praziquantel treatment involves exposure of surface spines consisting of ‘paracrystalline’ actin and a subsequent host response against actin through mechanisms established in the host independently from schistosomal infection. Drug-induced exposure of actin was demonstrated by fluorescence microscopy using anti-actin antibodies and phallacidin, an actin-binding mushroom toxin. Actin spines remained intact at the schistosome surface after in vitro exposure, but spine morphology was lost after in vivo exposure to praziquantel. Disintegration of spines in vivo was associated with binding of host antibodies. In vitro spine destruction could be seen in the presence of normal human serum. The effect was linked to calcium-dependent binding of actin depolymerizing factor, gelsolin.

Patients with systemic autoimmune disorders produce autoantibodies against sequence-specific conformational RNA epitopes on U1 snRNA, 28S rRNA, and transfer RNAs. The molecular basis for immunological reactivity with these highly abundant and stable RNAs is not understood. Here, we report the existence of discrete RNA epitopes in messenger RNAs that are generally less abundant and less stable than snRNAs and tRNAs. An iterative selection and amplification procedure using pooled autoimmune patient sera identified immunoreactive mRNA species. Following deconvolution of the pools to identify the reactive sera, several mRNAs recognized by these autoantibodies were cloned and sequenced. Detailed analysis using one particular serum indicated reactivity against the messages encoding alternative splicing factor (ASF/SF2) and calmodulin. Deletion and site-directed mutagenesis determined that an epitope recognized by this serum is located in a 17-base stem-loop structure common to both messages. This serum was then used to immunoprecipitate native mRNAs encoding ASF/SF2 and calmodulin from total HeLa cell RNA. Our results demonstrate that despite its low abundance and instability, messenger RNA is capable of reacting with autoantibodies generated during an autoimmune response. These data are consistent with direct presentation as a model to explain the generation of RNA conformation-specific autoantibodies.

Sera of some patients afflicted with the inflammatory disease myositis contain antibodies of the anti-PL-12 type. A fraction of these polyclonal autoantibodies specifically precipitates the fully matured human tRNAAla bearing the anticodon IGC (PL-12 antigen). Earlier work (Bunn & Mathews, 1987, Science 238:116–119) had shown that the epitopes are located entirely within the anticodon stem-loop of the tRNAAla. Here we demonstrate that human anti-tRNAAla autoantibodies immunoprecipitate a synthetic polyribonucleotide containing inosine (I) and N1-methylinosine (m1I) separated by 2 nt as in the anticodon stem-loop of human tRNAAla. The shortest polyribonucleotide that can be immunoprecipitated corresponds to the pentanucleotide IpGpCpm1IpUp, which corresponds to part of the anticodon loop of human tRNAAla and lacks the stem-loop structure. The efficiency of immunoprecipitation was about four times greater with longer polyribonucleotides capable of forming a stem-loop structure, and was abolished by altering the relative positions of I and m1I within the synthetic polynucleotide. Synthetic oligodeoxyribonucleotide analogs of the tRNAAla stem-loop, containing the sequence dIpdGdCdm1Ip, are not antigenic. Our results show that human anti-tRNAAla autoantibodies selectively recognize chemical details of modified nucleotides (the 6-keto group of inosine-34 and the 6-keto group and the N1-methyl groups of N1-methylinosine-37) within an anticodon loop structure of a tRNA molecule. We also describe the chemical synthesis of the phosphoramidite derivatives corresponding to N1-methylinosine and N1-methyl-2′-deoxyinosine for use in the automatic chemical synthesis of oligonucleotides containing N1-methylinosine and N1-methyl-2′-deoxyinosine.

Type 1 diabetes mellitus (IDDM) results from a chronic process of autoimmune destruction of ß cells of the Langerhans islets. The presence of autoantibodies (ICA, GADA, anti-IA2, IAA) in serum preceds the clinical onset of the disease. Genetic predisposition for IDDM is connected with HLA, CTLA-4 and insulin gene region.

The aim of the study was the genetic and immunological analysis of a triplet. One of them developed Type 1 diabetes mellitus. We analysed HLA class II, CTLA-4 and insulin gene polymorphisms in the whole family. Besides, we investigated immunological status of three brothers.

All patients present identical genotype for VNTR loci: D1S80, D17S5 and Apo B, as well as for HLA-DRB1, — DQA1, — DQB1, CTLA-4 gene and all studied insulin gene polymorphisms. That proves their monozigosity. The triplet presents strong genetic predisposition for IDDM. The two patients without overt diabetes have increased levels of ICA, GADA, IA2 and IAA.

We have previously reported that the mechanisms of neuromyopathic damage induced by Trypanosoma cruzi are mediated by T cells and are parasite-strain dependent. In the present study our aim was to determine whether the humoral response against muscle and nervous system is also parasite-strain dependent. Of the sera from mice infected with RA and CA-I T. cruzi strains, 93% reacted against antigens of the nervous system (sciatic nerve, spinal cord and brain). No differences in the ability to recognize heart antigens were found between RA (48%) and CA-I (63%) antisera. Reactivity against skeletal muscle was only relevant in anti-CA-I sera at 270 days post-infection. Each of the antisera assayed in Western blots developed a particular antigenic pattern, but 3 antigens in the nervous system of molecular weight 48, 60 and 70 kDa were detected by 42, 28 and 23% of the sera, respectively. On the other hand, deposits of IgG were observed at the interstitial matrix in sciatic nerve and as endomisial and sarcolemmal patterns in skeletal muscle by IFAT for both RA and CA-I antisera. Absorption of sera with parasite antigens did not abolish the autoreactivity. Our results suggest that major serum autoreactivity from T. cruzi-infected mice is not parasite-strain dependent and does not arise from molecular mimicry.

In this study, we investigated the relative localization of some antigenic epitopes in the inner ear. The inner ear protein antigens were extracted from various parts of the guinea pig inner ear. Brain, kidney, lung, heart and liver extracts were also obtained. We found by SDS-polyacrylamide gel electrophoresis that total inner ear extracts separated into three high concentration polypeptide bands with molecular weights of approximately 30, 42, 58 kd and three low density bands of 20,25 and 35 kd. The 30 kd band was found mainly in the extract of the spiral ganglion and the acoustic nerve in the modiolus. The 42 and 58 kd bands were detected in the extract of the spiral ligament and the stria vascularis. The Organ of Corti and the basilar membrane extract gave rise to three bands of 30,42 and 58 kd. Twenty-eight of the 75 sera from patients with inner ear disease reacted with the 30 and 58 kd bands of the inner ear protein extracts by immunoblotting. Sixteen of these 28 positive sera were then used to probe immunoblots of the brain, kidney, lung, heart and liver extracts. The 58 kd band was also found in protein extracts of the brain, the lung and the liver. This study suggests that the 30 kd antigenic epitope may be mainly related to the acoustic nerve and that the 58 kd antigenic epitope is not cochlear specific.