Frequency and clinical pattern of celiac disease among siblings of celiac children

To investigate the prevalence and clinical and genetic patterns of celiac disease (CD) among siblings of CD patients, 103 siblings and one twin of 80 celiac children were evaluated by means of their clinical history, physical examination, blood indices of nutritional status, and antigliadin antibodies (AGA). Antiendomysium antibody (AEA) levels were determined in 70 patients and 85 subjects were human leucocyte antigen (HLA) typed. On the basis of clinical or laboratory data or both, 21 siblings (20.2%) were submitted to intestinal biopsy, whereas intestinal biopsy in six siblings with positive serologic screening (AGA IgA or AEA or both) was not performed because of parental refusal. In a high percentage of cases (18%), all on a gluten-containing diet, the intestinal mucosa was atrophic, and CD was subsequently diagnosed. Because we could not submit all the siblings to intestinal biopsy, this figure could underestimate the real prevalence of the disease in our series; consequently, it was not possible to calculate accurately the sensitivity and specificity of AGA and AEA. Nevertheless, AEA (positive in all the nine siblings with mucosal atrophy), followed by AGA IgA, proved to be the best screening for CD. Eighteen of 19 CD siblings showed HLA-predisposing antigens. Among the 19 CD siblings, one showed a typical form with gastrointestinal symptoms, two had short stature, one suffered from recurrent vomiting, and in 15, the disease was clinically silent. On the contrary, among siblings who were first diagnosed (index cases), the majority (73.7%) had a typical form of CD, and no clinically silent cases were observed. We did not find any difference between index cases and CD siblings in food habits and distribution of HLA antigens. In 15 of 18 cases, the sibling diagnosed subsequently was the older one. Finally, the typical form of CD was significantly more frequent among the younger brother than the older. In conclusion, the high prevalence of the silent form of CD in our cases indicates that siblings of CD subjects should always be screened for CD. The combination of AGA IgA and AEA represent a good screening method to use in selecting children for the intestinal biopsy.

Definition of the initial immunologic modifications upon in vitro gliadin challenge in the small intestine of celiac patients

BACKGROUND & AIMS

Mucosal cell-mediated immune response is considered the central event in the pathogenesis of celiac disease. In cultured intestinal explants from celiacs in remission, we have characterized the early stages of gliadin-induced immune activation.

METHODS

Intestinal biopsy specimens (15 treated celiacs and 13 controls) were cultured with gliadin or maize prolamine digests for 24 hours as well as for 1, 2, 4, 6, 8, and 12 hours in some subjects. The expression of immunologic markers was detected by immunocytochemistry.

RESULTS

Gliadin challenge may initiate two parallel pathways, one of which leads to T-cell activation and another that precedes it. Epithelial cells overexpress DR molecules after 1 hour, and in a second stage T lymphocytes become fully activated. Moreover, T lymphocytes migrate in the upper mucosal layers. T lymphocytes that migrate in the higher lamina propria compartments are mainly CD4+ and show markers of activation; migrating intraepithelial lymphocytes are CD8+ and do not express these markers.

CONCLUSIONS

In vitro gliadin challenge is a suitable model to reproduce various immunologic features of celiac lesions; these may be caused by different pathways. The comprehension of these phenomena is essential to clarify the distinctive pathogenic mechanisms leading to disease and may help in defining novel therapeutic approaches.

Distinctive features of the alpha 1-domain alpha helix of HLA-C heavy chains free of beta 2-microglobulin

Only a few monoclonal antibodies are available with a restricted specificity to HLA-C products. In the present report, we demonstrate that antibody L31, previously shown to react with beta 2m-less (free) class I MHC heavy chains, binds to an epitope (residues 66-68 of the alpha 1 domain alpha helix) present on all the HLA-C alleles corresponding to the accepted (CW1 through CW8) serologic specificities, and on a few HLA-B heavy chains sharing with HLA-C an aromatic residue at position 67. Extensive IEF blot testing of HLA homozygous, EBV-transformed B-lymphoid cells indicates that HLA-C molecules are present at significantly lower levels than HLA-B polypeptides not only at cell surface, as previously demonstrated, but also in total cellular extracts. Testing of metabolically labeled HLA-CW1, -CW5, and -CW6 transfectants and HLA homozygous lymphoid cells, particularly HLA-CW1-expressing cells, demonstrates that the L31 epitope is present on a subpopulation of naturally occurring HLA-C molecules distinct from that identified by antibody W6/32 to beta 2m-associated heavy chains. Pulse-chase experiments demonstrate that this epitope is transiently made available to antibody binding at early biosynthetic stages, but becomes hidden upon assembly with beta 2m. Thus, free HLA-C and other Y/F67+ heavy chains are characterized by distinctive antibody binding features in a region (residues 66-68) included in a previously identified HLA-C restricted motif, which has been suggested to be the primary cause of distinctive features of the antigen-binding groove, low affinity for endogenous peptide antigens and beta 2m, and preferential uptake of exogenous peptides, possibly of viral origin. We also show that HLA-CW1 heavy chains, both free and beta 2m associated, acquire sialilation. Free HLA-CW1 heavy chains are expressed at the cell surface even when unsialilated, albeit at low levels.

Polymorphism in the upstream regulatory region of DQA1 gene in the Italian population

Polymorphism in the 5'-upstream regulatory region of the DQA1 gene has been recently described. Using PCR-SSO method and SSCP analysis we have investigated this polymorphism in a group of 111 Italian blood donors which had been oligotyped for DRB1, DQA1 and DQB1 genes. Eight allelic variants were detected. Looking at the relationships among QAP sequences and DQA1 and DRB1 genes, three alternative situations were found: 1. a one-to-one relation between QAP and DQA1 alleles, independently of the other class II genes; 2. the same QAP allele in association with different DQA1-DRB1 haplotypes; 3. the same DQA1 allele with different QAP sequences according to the DRB1 specificity. No unexpected associations with DQB1 gene were found. These results must be interpreted considering that DQA1 and DRB1 genes are transcribed in opposite directions so that the promoter region of DQA1 gene lies between DQA1 and DRB1, close to the former but several hundreds kb away from the latter.

Coeliac disease, enamel defects and HLA typing

The presence of dental enamel defects in coeliac disease and their relation to hypocalcaemia or a particular HLA class in 82 Italian children with coeliac disease was studied. Demarcated opacities or hypoplasia were detected in 23 subjects (group 1) while minimal or no dental lesions were found in the remaining 59 patients (group 2); in 189 normal controls, enamel lesions were significantly less frequent than in patients with coeliac disease (14.8% versus 28.0%; p < 0.005). No statistically significant differences were found for age at diagnosis and calcium concentrations between groups 1 and 2. Regression analysis showed a correlation between age at diagnosis and number of teeth with enamel defects. In our patients, the presence of HLA DR3 antigen significantly increased the risk of dental lesions, while genotype DR5,7 seemed to protect against enamel defects. A logistic regression analysis of the variables age, serum calcium concentrations, number of affected teeth, type of enamel defect and DR antigens showed that only DR antigens discriminated coeliac disease patients with from those without enamel defects.

Different dose effect of HLA-DQ alpha beta heterodimers in insulin-dependent diabetes mellitus and celiac disease susceptibility

To compare the quantitative effect of the DQ alpha beta heterodimers DQ alpha 52 Arg+, beta 57 Asp- and DQ alpha 1*0501, beta 1*0201 on susceptibility to IDDM and CD, we characterized, at the genomic level, the DQ alpha 52 and DQ beta 57 residues of 50 IDDM Italian patients observed in Rome. The results were compared with those of a previous study concerning the oligotyping of DQ dimers in a group of CD children belonging to the same population. Our data confirm that both diseases are primarily associated with HLA-DQ alpha beta heterodimers, but the distributions of the respective susceptible DQA1 and DQB1 alleles in the two diseases were different. In fact, the highest risk of IDDM is for subjects alpha SS, beta SS that could express, by either cis- or trans-association, four susceptible heterodimers and decreases in proportion to the number of these; in regard to CD, the highest risk was found for individuals who carried only one predisposing heterodimer.

A study of Italian pediatric celiac disease patients confirms that the primary HLA association is to the DQ(alpha 1*0501, beta 1*0201) heterodimer

Celiac disease (CD) has been recently reported to be primarily associated with the DQ(alpha 1*0501, beta 1*0201) heterodimer encoded in cis on DR3 haplotype and in trans in DR5,7 heterozygous individuals. The high incidence of DR5,7 heterozygotes, reflecting the high frequency of the DR5 allele in Italy, makes the analysis of the Italian CD patients critical. Polymerase chain reaction-amplified DNA from 50 CD patients and 50 controls, serologically typed for DR and DQw antigens, was hybridized with five DQA1-specific oligonucleotide probes detecting DQA1*0101 + 0102 + 0103, DQA1*0201, DQA1*0301 + 0302, DQA1*0401 + 0501 + 0601, and DQA1*0501 and a DQB1-sequence-specific oligonucleotide probe recognizing DQB1*0201 allele. As expected by the DR-DQ disequilibria, DQA1*0201 [62% in patients versus 26% in controls, relative risk (RR) = 5] and DQA1*0501 (96% versus 56%, RR = 19) show positive association with the disease. Of CD patients, 92% (50% DR3 and 42% DR5,7) compared to 18% of the controls carry both DQA1*0501 and DQB1*0201 alleles, so that the combination confers an RR of 52, higher than both the risks of the single alleles (DQA1*0501 RR = 19, DQB1*0201 RR = 30), confirming the primary role of the dimer in determining genetic predisposition to CD both in DR3 and in DR5,7 subjects.

Oligotyping of Italian celiac patients with the 11th International Histocompatibility Workshop reagents

Oligotyping for HLA-DRB1, DQA1 and DQB1 specificities has been performed on PCR-amplified DNA from 55 Italian celiac children, living in Rome, and 50 blood donors. 52.6% of CD patients were DR3;DQA1*0501;DQB1*0201-positive versus 14% of controls (RR = 6.85) and 34.5% were DR5,7;DQA1*DQB1*0201-positive versus 2% of controls (RR = 25.86). 7 patients (12.7%) were negative for the DQA1*0501/B1*0201 dimer: 3 of them were DR4 (5.4%) and the others typed as DR1,5; 1,7; 5,7 and w6,7. No patient was negative for both DQA1*0501 and DQB1*0201 alleles.

Oligotyping of celiac multiplex families with the 11th International Histocompatibility Workshop reagents

Using PCR and SSO probes from the 11th International Histocompatibility Workshop, we oligotyped for HLA-DRB1 gene and DQA1*0501, DQB1*0201 alleles 10 celiac families each with 2 affected children. All families belong to the Italian population except for one, whose mother is originally from Cape Verde island. 8/10 sibling pairs share the DQA1*0501/B1*0201 heterodimer, inherited in cis or in trans arrangement. All the dimer-negative patients were DR4-positive.

An anti-HLA class I monoclonal antibody alters the progression in the cell cycle of phytohemagglutinin-activated human T lymphocytes

The monomorphic anti-HLA Class I monoclonal antibody 01.65 inhibits the incorporation of tritiated thymidine ([3H]TdR) in Phytohemagglutinin (PHA)-activated human T lymphocytes. Our data indicate that 01.65 affects the average duration of the cell cycle by increasing the length of the early S subphase. As a consequence of the increase in the doubling time of the cell population, the absolute number of cells at harvesting time was reduced in 01.65-treated cultures compared to that of untreated cultures. The lengthening of the S-phase and the decrease in the cell number can together quantitatively account for the reduction of [3H]TdR incorporation observed in 01.65-treated cultures.

Expression of class II MHC antigens in the intestinal epithelium of pediatric celiac disease

Class II MHC antigen expression in the intestinal epithelium of 28 small bowel biopsies from 23 celiac patients were studied by means of indirect immunofluorescence and immunoperoxidase using monoclonal antibodies. Patients were divided on the basis of diet into two subgroups: 15 subjects on a gluten-containing diet (GCD) and 13 on a gluten-free diet (GFD). The control group included 10 pediatric subjects with normal intestinal mucosa who underwent intestinal biopsy for chronic diarrhea or short stature. DR antigens and invariant chain were expressed in all patients, regardless of the diet, as well as in the control subjects. DQ was found in one patient only on GCD. DP antigens were present in 12/15 patients on GCD, and in 2/13 on GFD (Fisher's exact test, p = 8.8 x 10(-4), as well as in 3/10 control subjects. In 4/5 celiac patients, DP antigens, which were undetectable on GFD, could be demonstrated after gluten challenge. The results of the study show that DR antigens are expressed by intestinal mucosa of celiac patients independently of their gluten exposure and that DQ antigens are consistently undetectable. Statistically significant differences in expression of DP antigens on enterocytes of celiac patients on GCD and their neoexpression after gluten challenge may represent a basis for further investigation.

mAb KUL/05 identifies a denaturation-resistant determinant shared by class II MHC products DR, DQ and DP

mAb KUL/05, a novel murine monoclonal antibody, reacts with molecules displaying the typical tissue distribution and molecular profile of class II MHC antigens. An extensive scrutiny employing serological and immunochemical assays on DR homozygous and DR alpha- mutant cell lines has shown that this reagent displays some additional, interesting features, namely mAb KUL/05 (a) binds in a broadly monomorphic fashion to cells of DR1 through seven specificities, (b) recognizes a determinant shared by a large proportion of DR, DQ and DP beta chains from most haplotypes, in both their monomeric and alpha chain-associated forms, and (c) reacts with frozen, acetone-fixed, as well as conventional, formalin-fixed, paraffin embedded tissues. Thus, mAb KUL/05 is likely to represent a useful adjunct for the study of the expression of class II MHC products in normal and pathological tissue specimens.

A study of HLA class II antigens in an Italian paediatric population with coeliac disease

One hundred and twenty-one Italian children with coeliac disease (CD) have been compared with a control population from the same geographical area for the distribution of HLA-DR and DQ antigens. The pattern of an increase in DR3, DR7, and of heterozygotes DR5/7 was associated with an excess of heterozygotes DQw2/DQw3 in the CD population. These findings suggest that epitopes determined by specific combinations of DQ alpha and beta chains (combinatorial determinants) predispose to the disease.

HLA antigens and adult rheumatoid arthritis: a study with a monoclonal antibody

Adult rheumatoid arthritis (RA) is a very heterogeneous disease that is associated with HLA-antigens, although no absolute association has been found with any particular HLA type. Forty-one seropositive RA patients have been studied with a local monoclonal antibody named X1 21.4 (9w940), strongly associated with HLA-DRI, DR4, Drw10 antigens, to verify a possible correlation with the disease. The results obtained have also been compared with the data reported on MC1, a serologically defined determinant correlated with RA. X1 21.4 monoclonal antibody appears to be associated with the disease and it could identify one epitope involved in the susceptibility to RA.

A mouse monoclonal antibody against a polymorphic determinant in a defined subset of DR molecules

The hybridoma technique was used to produce a mouse monoclonal antibody, designated as XI 21.4, which belongs to the IgG2a class. It is active in complement-dependent cytotoxicity and detects a B-cell antigenic determinant associated with DR1, DR4, DRw10, and, possibly, DRw9. Microfingerprinting of the immunoprecipitate from a homozygous DR4 cell line shows a typical alpha DR pattern and a beta pattern coinciding with that of DR4 molecules.

Monoclonal antibodies to HLA-DP-transfected mouse L cells

Mouse L cells transfected with human HLA-DP (DPw4) alpha and beta genes were used to make monoclonal antibodies in C3H mice. A polymorphic antibody, DP11.1, was obtained, as well as several monomorphic antibodies. In ELISAs, DP11.1 bound to DPw4 cells and, more weakly, to DPw2, but not DPw1, -3, -5, or -6, using HLA homozygous cells. It also bound to L-cell transfectants expressing either DPw2 or DPw4 products. From B lymphoblastoid cell lysates labeled with [35S]methionine, the antibody immunoprecipitated alpha and beta chains of a similar size to those precipitated by a well-characterized DP monoclonal antibody, B7/21.2. Immunoblotting indicated that the DP11.1 antibody was directed against the alpha chain. This result confirms partial sequence data that showed that the DP alpha chain, as well as DP beta, is polymorphic, and that DPw2 and -4 alpha chains are very similar, if not identical.

A nonneutralizing human IgM monoclonal antibody inhibiting hemagglutination of H3N2 influenza A strains

A mouse-human hybridoma has been produced by fusing human splenocytes from a Cooley's anemia patient with the murine myeloma P3-NS1/1-Ag 4-1. The hybridoma is stable after 18 months and secretes human IgM. The antibody reacts with some H3N2 influenza A strains and detects an epitope that is part of the hemagglutinin antigen, but does not affect virus infectivity.

A cytotoxic anti-HLA-AB monoclonal antibody which in dilution becomes specific to HLA-A3 crossreacting group

XI 20.4 monoclonal antibody belongs to the IgM class. It precipitates two polypeptide chains characteristic of HLA Class I antigens. At the highest dilutions it is cytotoxic against lymphocytes carrying antigens of the HLA-A3 crossreacting group. Lysostrip experiments show that, at the lowest dilutions, the antibody reacts either with HLA-A, or B antigens.

HLA-ABC and DR antigens in celiac disease. A study in a pediatric Italian population

HLA phenotypes of 64 Italian pediatric patients with celiac disease (CD) were compared with those of a group of healthy controls. DR3 and DR7 are significantly increased as reported in other populations. In addition an increase of heterozygotes DR5/DR7 was observed in our patients. The Hardy-Weinberg distribution in the patients group shows a disequilibrium due to the genotype DR5/DR7. Our data confirm that more than one HLA gene product is associated with CD: one with DR3 and the other with DR7.

A mouse monoclonal antibody detecting the allospecificity HLA-A3

Balb/c mice were immunized with a human B-lymphoblastoid cell line typed HLA-A3, B7. The splenocytes of the immunized mice were fused with a murine myeloma. Supernatants of the cultures were screened against the immunizing cell line in fluorochromasia. Positive cultures were expanded and cloned. One of the clones, X 15.4, was expanded and brought to ascites in Balb/c mice. Monoclonality of the antibody X 15.4, which belongs to the class IgM and immunoprecipitates a molecule of 44000 daltons, was demonstrated by isoelectric focusing. By complement dependent cytotoxicity the ascites only reacted with the lymphocytes of all HLA-A3 individuals from a panel of 146 donors, showing no crossreactions. X 15.4 appears to be one of the very rare xenomonoclonal antibodies suitable for HLA typing.

Delineation of syndromes due to partial 6q imbalances. Trisomy 6q21 leads to qter and monosomy 6q221 leads to qter in two unrelated patients

Two unrelated patients carrying imbalances involving the long arm of chromosome 6 are described. In the first trisomy 6q21 leads to qter had segregated from a maternal translocation t(6;16)(q15;q24). The clinical data of the proposita are compared with those of three other published cases. A partial 6q trisomy syndrome is postulated characterized by: growth deficiency of prenatal onset, psychomotor retardation, craniofacial abnormalities (microcephalia, hypertelorism, downward slanting palpebral fissures, flattened nasal bridge, long philtrum, hypoplastic perioral features, large jaw resulting in a round appearance of the face, receding chin, malformed ears) and dysmorphic extremities (contractures of limbs due to short flexor tendons, hypoplastic fingers, toes and nails). In the second case, monosomy 6q221 leads to qter resulted from a de novo rearrangement and was responsible for mental retardation and facial dysmorphism (reduced biparietal diameter, hypotelorism, absent eyebrows, prominent nose, ptosis, receding chin, dysmorphic ears). Studies of HLA and PGM3 segregation showed normal inheritance patterns and ruled out the location of these genes in bands 6q221 leads to qter.