Genetic, immunologic, and environmental heterogeneity of IDDM. Incidence and 12-mo follow-up of an Italian population.

The 1-yr incidence of insulin-dependent diabetes mellitus (IDDM) in a population of the Piedmont and Aosta Valley area of Italy was recorded. Anti-virus antibodies (e.g., Coxsackie B1-6, mumps, cytomegalovirus), islet cell antibodies (ICAs), and HLA-A, -B, -C, and -DR were determined in 74 IDDM patients (38 males, 36 females) and in controls. Total IDDM incidence was 5.0/100,000, and the incidence for those less than 20 yr of age was 11.6/100,000. Anti-virus antibody frequency was not different in IDDM patients and controls. ICAs were present in 58% of IDDM patients at onset and in 30% after 12 mo, and complement-fixing ICAs were found in 39 and 17%, respectively. IDDM was significantly and positively associated with DR3/DR4 and negatively associated with DR2 and DR5. ICA frequency was significantly higher in DR3/DR4 heterozygote patients than in patients without DR3 and DR4. These results suggest that in this IDDM population viral etiology is not evident, ICAs offer only a partial pathogenetic explanation, and genetic and immunologic heterogeneity is evident.

Familial membranous nephropathy.

Numerous HLA studies suggest that genetic factors play an important role in the development of membranous nephropathy (MN). We studied seven patients with idiopathic MN, from three unrelated families of Italian ancestry. Complement phenotype analysis and restriction fragment length polymorphism (RFLP) typing of HLA class II and of the switch region genes were done in family members. In the first family, the father, one son, and one daughter had MN; another daughter had clinical glomerulonephritis. The three members with MN shared one HLA haplotype carrying DR beta 11; in the two siblings with the disease, the second HLA haplotype carried the DR beta 3.2 allele. In families 2 and 3, two brothers had MN: in family 2, they differed in at least one haplotype; in family 3, they differed in both haplotypes. Only family 3 was informative with regard to the RFLP of the switch region genes: the two siblings were identical for both Ig heavy chain haplotypes. No clinical, laboratory or morphologic features consistent with a secondary form of the disease were found. Familial clustering of MN suggests a genetically transmitted mechanism.

[The Italian Registry of Bone Marrow Donors: genetic structure and recruitment strategy]. / Il Registro Italiano dei Donatori di Midollo Osseo: struttura genetica e strategie di reclutamento.

The genetic structure of the Italian bone marrow donor population was analysed by estimating the HLA-A, -B and -DR gene and haplotype frequencies for the total population and for the Italian administrative regions. The haplotype frequencies were used to predict the probability of finding HLA-compatible donors for Italian patients depending on the registry size, and the probability of recruiting in the different Italian regions a donor with a new phenotype. The analysis of these probabilities allows us to propose strategies for donors recruitment in order to increase the phenotypic variability of the registry, then its efficiency.

Proficiency testing for HLA-DRB high-resolution typing: a 4-year experience in Italy.

Twenty-one Italian laboratories participated for four consecutive years in the collaborative Italian proficiency testing of HLA class II (DRB1, DRB3, DRB4 and DRB5) high-resolution typing. In this paper the results are analysed. Seven different kinds of errors are described and discussed. The errors were divided into technical errors and errors of allele reporting. Each year, a list of errors made was prepared by our laboratory and discussed collegially with all laboratories. The allele reporting errors diminished over time, as a result of the common discussions. The technical performance of the laboratories did not improve overall for the 21 laboratories participating: for 16 of them results were good or improved in quality, but for the remaining five results deteriorated over time. From this experience, some recommendations for the future emerged. A relevant conclusion was that, to improve the performance of a group of laboratories, the proficiency test is not effective alone, but should be integrated within a framework of continuous collaboration and mutual technical help.

A new duplication at the C4B locus associated with the HLA-Aw68, Cw8, Bw65 haplotype.

A family with a cross-over between HLA-B and HLA-DR was analysed for its complement alleles. This allowed location of the cross-over between HLA-B and C4. Furthermore, the same family showed a previously undescribed duplication at the C4B locus (C4B* 2,2) that was associated with the HLA-Aw68, Cw8, Bw65, C2*1, Bf*S, C4A*2, DR7, DQw2 haplotype.

Evaluation of different technical approaches for the research of human anti-Ia alloantisera.

Several strategies have been proposed for the research of human anti-Ia alloantisera. The present work evaluates the results of a screening made on multiparous sera, using either platelet-absorbed sera or unabsorbed sera against cells coated by anti-human-beta-2-microglobulin antibodies. When the results of the two approaches were compared, it was observed that the latter shows a higher frequency of positive reactions, being able to detect weak anti-Ia, and possibly non-HLA antibodies, which are not revealed with the usual test on platelet-absorbed serum. A significant correlation has been noted between the presence of anti-HLA-A,B,C and of anti-Ia, demonstrating that the best source of Ia antibodies from multiparous women are sera also containing anti-HLA-A,B,C.

HLA polymorphisms in Italian bone marrow donors: a regional analysis.

The aim of this study was to analyse the genetic structure of the Italian bone marrow donor population on the basis of HLA polymorphisms. Maximum likelihood estimates of gene and haplotype frequencies, goodness of fit to Hardy-Weinberg predictions and heterozygosity were calculated for 18 Italian administrative regions. Moreover, the phenotypic peculiarity of the regional populations was assessed by analysing the number of "typical phenotypes" found in each region. Multivariate analyses carried out on HLA-A and HLA-B gene frequencies gave a genetic pattern of the donor pools that reflects the structure of the Italian population determined in previous population genetic studies. Sardinia shows a very large genetic difference with respect to the other regions; of these, the central-southern regions are well-differentiated from the central-northern. Southern regions present higher genetic heterogeneity and a higher probability of providing donors with phenotypes not already present in the Italian bone marrow registry. The large sample size of the bone marrow donor registry allowed us to estimate gene and haplotype frequencies with greater accuracy than in previous studies. Our results may be of use in determining strategies for donor recruitment and selecting unrelated donors for patients requiring bone marrow grafting, as well as for anthropological, epidemiological and population genetics studies.

Characterization by monoclonal antibodies of lymphocyte subsets present in B-enriched suspensions.

B lymphocyte enriched suspensions isolated by E rosette depletion (E-cells) or by nylon fiber adherence (adherent cells) were identified by their cellular composition using different T and B cell markers (SIg,E receptor, T3, T4, T8 and Ia-like antigens). The cells were isolated from peripheral blood both of healthy donors and uremic dialysis patients. A variable proportion of non-B cells was found in some preparations. This contaminant was represented mainly by Null cells in E-lymphocyte suspensions and by T cells in the adherent population. Contaminating T lymphocytes were most frequently found in adherent cell preparations from uremic individuals and appeared to be an heterogeneous population including variable proportions of T4, T8 and Ia positive T cells. A significant increase of T8+ cells and a decrease of the ratio T4/T8 was seen among adherent T cells as compared to the normal distribution among T peripheral lymphocytes.

Persistence of cytotoxic antibodies to HLA-A,B,C antigens and to Ia-like antigens in parous women.

Cytotoxic antibodies to HLA-A,B,C and to Ia-like antigens were detected in about 8% of sera drawn from 1312 women several years after their last pregnancy. In the majority of sera anti Ia-like antigen antibodies were not associated with anti HLA-A,B,C antibodies. Persistence of both types of antibodies was not correlated with the number of pregnancies and with the time interval between the last immunizing stimulus and the drawing of the sample. Testing of the sera with a panel of HLA typed lymphocytes identified 20 sera specific for HLA-A,B alloantigens and 7 specific for Ia-like alloantigens.

HLA haplotypes and hormonal studies in 25 Italian families of patients with classical and non-classical 21-OH deficiency.

To investigate the genetic polymorphisms of the HLA region and the molecular defect of the P450c21B gene in congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, we studied 89 individuals from 25 families of CAH patients (14 classical forms, 11 non-classical forms). The following immunogenetic and hormonal investigations were performed: HLA-A and B typing, restriction fragment length polymorphism (RFLP) analysis of 21-hydroxylase A and B genes, and serum 17-OH-progesterone values determined basally and 60 min after ACTH stimulation. In the patients affected by the classical form, RFLP analysis revealed 5 deletions and 1 gene conversion in 6 haplotypes and no molecular defect in the others, who probably carry point mutations. In the patients with non-classical form we found P450c21A duplication in 11/18 haplotypes; 9 of the 11 patients shared the HLA-B14 allele. Utilizing both hormonal and genetic data we identified two cryptic forms; hormonal data alone failed to differentiate heterozygous from normal individuals.

Properdin factor B polymorphism in four Sardinian villages.

A sample of healthy unrelated individuals was typed for properdin factor B (Bf) polymorphism in four Sardinian villages. Two villages, Desulo and Tonara, are located in the highlands; the other two, Orosei and Galtellì, are located in the lowlands. No heterogeneity was found between the highland and the lowland villages, whereas a significant difference was found between the Sardinian villages and continental Italy. The allele Bf-F1 shows the highest gene frequency so far observed. Typically Sardinian is the gametic association (haplotype) HLA-A30, Cw5, B18, BfF1, DR3.

[Analysis of a sample of the Italian population for HLA-DR antigen. Gene frequencies and gametic associations]. / Analisi di un campione della popolazione Italiana per gli antigeni HLA-DR. Frequenze geniche ed associazioni gametiche.

A random sample of 177 individuals from the Italian population was typed for eight HLA-DR antigens. Gene frequencies and linkage disequilibria were calculated. The most different frequencies, when compared with other european populations, are those of DR5 and DRw6. Most of the linkage disequilibria observed are the same found in other european populations, but some disequilibria present only in Italian population were also observed.

Split of HLA-DRw2 into subtypic specificities closely correlated to two HLA-D products.

Two B-lymphocyte-specific human alloantisera were studied, PA59 and 51.23. They identify two new HLA-DR alleles, which are both subtypic to HLA-DRw2. Moreover, they are closely correlated with two HLA-D products, Dw2 and tb24 (tb24 is a new specificity described by our group). Thus, DRw2 can be "split" into two subtypic specificities that have been named TO60 and TO61, which appear more strongly correlated with HLA-D antigens. Absorption studies demonstrated cytotoxicity-negative, absorption-positive (CYNAP) reactions, and cross-reactive groups of antibodies.

Distribution of tumor necrosis factor alleles (NcoI RFLP) and their relationship to HLA haplotypes in an Italian population.

The NcoI RFLP of the tumor necrosis factor (TNF) beta gene was analyzed in a panel of 105 unrelated healthy Italian blood donors. The gene frequencies of the 10.5 kb and 5.5 kb allele were 0.73 and 0.27, respectively. The 5.5 kb band was significantly positively associated with HLA-A1, B8, DR17.1, and C4AQ0, and negatively associated with DR7.2, DQw9 and C4A6, all being specificities which belong to two well-known Caucasoid ancestral haplotypes. When the population was subdivided on the basis of TNF phenotypes, different linkage disequilibria between HLA alleles were detected in the three phenotypic classes. From this analysis it was possible to relate preferential HLA associations, most of which are characteristic of ancestral haplotypes, to TNF polymorphism.

HLA-DR3 and DR7 in coeliac disease: immunogenetic and clinical aspects.

The association of HLA-A,B,C, DR polymorphisms and of Bf and GLO with coeliac disease was analysed in 100 Italian children. Primary involvement of HLA-DR3 and DR7 is apparent, while specificities of nearby loci are probably associated secondarily, because of linkage disequilibrium. Direct assessment of D/DR genotype through family studies and mixed lymphocyte cultures led to the recognition of two high risk genotypes DR3/3 and DR3/7, and of two lower risk genotypes DR3/X and DR7/X. The different weight of the HLA-dependent genetic factors is to some extent correlated with the clinical and immunological parameters, suggesting that the low-risk genotypes induce a milder expression of coeliac disease. Furthermore, other genetic factors, such as sex, appear to contribute to the penetrance of the disease, especially in the case of DR3/X and DR7/X.

HLA antigens in juvenile dermatitis herpetiformis.

The incidence of histocompatibility antigens HLA-A, B, C, DR was studied in 32 Italian children with dermatitis herpetiformis. A significantly increased relative risk was found for B8 (R.R.=6.2), which was present in 50% of the patients as against 14% of the controls and for DR3 (R.R.=11.7), present in 69% of the patients as against 16%. DR7 also appeared to be increased, but only among DR3-negative patients. There was no significant difference in the incidence of DR3 between children with abnormal and normal jejunal biopsy, though there does seem to be a difference in expressivity of the intestinal involvement between DR3 apparent homozygous, DR3 heterozygous and DR3-negative patients.

Two HLA-D and DR alleles are associated with coeliac disease.

A group of 45 children affected with Coeliac Disease (CD) was typed for HLA-A, B, C, D, and DR specificities. The most significant associations were found with two alleles of the D series, with both cellular and serological typing. It is suggested that the susceptibility to CD is determined by two different genes within the HLA region, the first in common with organ-specific autoimmune diseases and associated with DW3, the second possibly specific for CD and associated with Dw7.

HLA-DR antigens in HBsAg-positive chronic active liver disease with and without associated delta infection.

The A, B, C and DR locus specificities of the human leukocyte antigens system (HLA) were determined in 45 delta-positive and 44 delta-negative Italian patients, all with HBsAg-positive chronic active liver disease; controls were 526 healthy Italian blood donors matched for age, sex and geographical origin. HLA-A, B, C gene frequencies were not significantly changed. In delta-positive patients, the frequencies of the DR locus specificities were: DR2, 37.8%; DR3, 20%; DR4, 11.1%. In the delta-negative patients, the frequencies were: DR2, 13.6%; DR3, 36.4%; DR4, 0%. Control frequencies were: DR2, 19.4%; DR3, 17.1%; DR4, 18.5%. The corrected p values of the differences between controls and delta-positive patients were: DR2, pc = 0.046; DR3, pc = NS (not significant); DR4, pc = NS. The corrected p values of the differences between controls and delta-negative patients were: DR2, pc = NS; DR3, pc = 0.03; DR4, pc = 0.002. These findings show that: (a) DR3, a genetic marker of autoimmunity, might assist the establishment of chronic HBsAg liver disease in the absence of delta superinfection; (b) DR2 is linked with failure to clear the delta agent, and (c) DR4 may protect from virus B persistence. Identification of adventitious factors such as delta may help uncover a subgroup of HBsAg carriers who are genetically predisposed to develop chronic liver disease.