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The literature of the past ten years shows that the introduction of highly purified heterologous and, lastly, homologous insulins has notably lowered the production of IgG and IgE specific insulin antibodies, but has not succeeded in completely eliminating clinical manifestations of the immune or hyper-immune response to insulin therapy. In particular, insulin allergy with or without lipodystrophy is still seen. Among the factors of insulin immunogenicity, there is a possible genetic control of the immune response in type I diabetes: determining HLA halloantigens (A, B, C, D) might identify specific immune response genes (Ir genes). Initial researches, performed until now almost exclusively upon diabetics treated with conventional heterologous insulin, seem to indicate a positive relationship between haplotype HLA - B15 - DR4 and an elevated immune response, whereas haplotypes HLA - B8 - DR3 and HLA - B18 - DR3 might protect against the formation of anti-insulin antibodies. Antigens D/DR3 and D/DR4 are known to be primitively associated to susceptibility for type I diabetes, whereas antigens B8, B15, B18 are secondarily associated to the rise in frequency of DR3 and DR4 for the "linkage disequilibrium" existing between alleles of B and D loci. The results of HLA typing are presented in 2 groups of insulin-dependent diabetics (ID) followed from an immunological viewpoint during therapy with monocomponent heterologous insulin for over 5 years. The first group is composed of 50 patients with low IgG anti-insulin antibody titers (less than 1 mU/ml, Christiansen: low responders); the second group is made up of 23 patients with high IgG anti-insulin antibody titers (greater than 2.5 mU/ml, Christiansen: high responders) and includes 5 subjects with insulin allergy (associated or not with insulin lipoatrophy) and high levels of insulin specific IgE antibodies. A study of the frequencies of various HLA-B antigens in both groups of patients, in regard to a control group of piemontese population, in relation to the intensity of association (relative risk) and to the statistical importance of frequencies, shows only a possible protective effect of the HLA-B18 phenotype (linkage disequilibrium with HLA - DR3) towards the production of anti-insulin antibodies and hyperimmune clinical manifestations, such as allergy. Reliable conclusions are not possible between low and high responders for the other phenotypes (HLA - B7, B8, B15) commonly implicated. HLA-B12 was noted in 3 of 5 patients with allergy, in 2 cases associated with B8.(ABSTRACT TRUNCATED AT 400 WORDS)

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 reassessment of HLA-A and B antigen associations in patients with severe aplastic anaemia confirmed the significantly elevated frequency of HLA-A2 in Caucasoid patients reported by Albert et al. (1976). In addition, a highly significant increase in the frequency of HLA-B14 in Italian patients was observed in an initial sample of 25 patients and confirmed in a second sample of 16 patients. This latter finding was cancelled out when the Italian Caucasoid patients were pooled with the non-Italian Caucasoid patients. These results suggest that the classification of populations as "Caucasoids", without examining their ethnic origins, may introduce a serious confounding error into HLA and disease studies.

A group of 20 patients affected with thyroid carcinoma, all from Southern Italy, was typed for HLA-A, -B, -C and -DR antigens. Sixteen of them (80%) typed for DR1, while in the control group (120 unrelated healthy individuals from the same region) only 22 (18.3%) shared the same antigen (chi 2 = 32.96). The data indicate a highly significant association between the HLA-DR1 gene and the thyroid carcinoma.

The HLA antigens are currently investigated in many diseases and are very useful in medico-legal tests for exclusion of paternity. However, because of the high polymorphism of the HLA system, for a correct interpretation of the results, it is essential to know the HLA antigens distribution in normal populations used as control. Up to now there are few studies about the HLA system in different regions of Italy and for this reason the Authors have studied the phenotypic, genic frequency and the gametic association of HLA A and B antigens in a population living in the province of Parma. The results confirm an HLA homogeneity of populations living it the western territories of the Emilia Region.

Thirty-eight Italian patients with Behcet's disease, all with ocular involvement, (28 complete type and ten incomplete) were typed for HLA A,B,DR, and DQ antigens. A significant increase of HLA-B51 (p less than 0.00001) and DRw52 (p = 0.045) with no significant difference between complete and incomplete syndrome was found. The involvement of B51 antigen as the main immunogenetic factor in the disease is suggested by the high value of relative risk (RR = 16.03). However, the association with the II class antigen DRw52 (RR = 2.77) cannot be easily explained as a secondary association due to linkage disequilibria with B51.

Twelve Sardinian patients affected by histologically defined classic Kaposi's sarcoma (KS) were HLA-A, B, C and DR typed. Compared to 220 age and ethnically matched healthy controls, KS patients showed a significant increase in HLA-DR5 (66.6 vs 23.1%, P less than 0.001) and a considerable decrease in HLA-DR3 (8.3 vs 53.6%, P = 0.0055). No definite association was observed for other HLA antigens. These results confirm the existence of an HLA associated genetic control of KS susceptibility and support the hypothesis that HLA-DR5 plays the role of a predisposition marker while HLA-DR3 bears a genetic resistance to the disease.

We investigated HLA antigen and haplotype frequencies in 47 couples with primary recurrent abortions of unknown origin, in 65 fertile couples, and in a control panel of 98 males and 92 females. A significant increase of HLA-B17 was found in abortion couples in comparison with fertile couples. No difference between abortion and control fertile couples was observed regarding HLA sharing.

Three generations of a not consanguineous Italian family and 40 subjects suffering from alopecia areata (AA) and residing in Northern Italy were studied. There were 321 healthy control subjects of both sexes. Six family members from three generations were affected with alopecia universalis. The subjects were HLA-phenotyped using different HLA-A, B and C antigen specificities. No significant association was found between HLA-A, B and C antigens and AA patients at the population level. Segregation analysis showed that affected members shared a common haplotype, HLA-Aw32, B18,-.