HLA-DP polymorphism in northern Italian celiac patients

Susceptibility to hard metal lung disease is strongly associated with the presence of glutamate 69 in HLA-DP beta chain

Clinical, epidemiological and experimental data indicate that inhaled metal dust containing cobalt may produce an interstitial lung disease termed "hard metal disease" (HMD). Some aspects of this pathology such as the lack of correlation with dose exposure, the low frequency of the disease and the presence of T cells in the inflammation site, all suggest the existence of a genetic susceptibility, possibly to an immunological response to cobalt or to self proteins modified by cobalt. Here we report that HMD is strongly associated with residue Glu-69 of the HLA-DP beta chain. All patients, except for one with a rare genotype, possessed this marker as compared to 17 out of 35 exposed unaffected individuals (p = 0.0014). These data allow us to genetically distinguish a subgroup of cobalt-exposed individuals at risk for HMD, independently from the more common allergic reaction.

HLA-DP antigens and post-streptococcal acute glomerulonephritis

We have typed 58 Japanese patients with post-streptococcal acute glomerulonephritis (PSAGN) for HLA-DRB1, DQA1, DQB1, DPA1, and DPB1 genes by the HLA-DNA typing method using a polymerase chain reaction (PCR)-sequence specific oligonucleotide probe (SSOP) technique. The control subjects were 317 healthy unrelated individuals. Frequencies of HLA-DPA1 02022 and DPB1 0501, which are in linkage disequilibrium and encode HLA-DP5 antigen, were significantly increased in patients with PSAGN than those in control (pc < 0.0005 and pc < 0.005, respectively). Frequencies of HLA-DPA1*01 and DPA1*0201 were significantly decreased in patients when compared with controls (pc < 0.05, for both). No significant difference in allele frequencies between the two groups was observed in the DRB1, DQA1 and DQB1 genes. This is the first report documenting the association of HLA-DP alleles with PSAGN. We speculate that HLA-DP5 antigens may be involved in the development of PSAGN.

Polymorphism of antigen processing (TAP, LMP) and HLA class II genes in celiac disease

Susceptibility to CD is strongly associated with particular HLA class II molecules. However, additive genetic factors are likely to be required for the development of the disease. The polymorphic TAP and LMP genes, located within the HLA class II region, are involved in the antigen presentation pathway and thus represent candidate susceptibility genes. HLA class II DRB1, DRB3, DQA1, DQB1, and DPB1 as well as TAP1, TAP2, and LMP2 polymorphism was studied in 80 Caucasian CD patients and 213 normal controls by DNA oligotyping. The DQB1*0201 allele was found in 96.3% of CD patients and provided the highest risk (RR = 50), whereas only 89% of CD patients carried the DQ alpha 501/beta 201 heterodimer (RR = 30). The participation of the DRB3 and DPB1 locus was ruled out as it was attributed to a linkage disequilibrium on the DR3 haplotype. TAP1 and LMP2 allelic distribution was not significantly different among CD patients and controls. The TAP2-C allele was completely absent from the CD population, while it was found in 22.5% of controls. Although linkage disequilibrium between TAP2 and class II loci clearly exists in some haplotypes, TAP could act as additional susceptibility genes.

HLA susceptibility genes in celiac disease: genetic mapping and role in pathogenesis

The overrepresentation of particular HLA alleles in patients with celiac disease was first noted two decades ago. Several lines of evidence obtained during the last years strongly suggest that a particular HLA-DQ heterodimer, encoded by the DQA1*0501 and DQB1*0201 genes in cis or trans configuration, confers the primary disease susceptibility. This paper reviews the evidence behind this concept and discusses how this particular DQ molecule may be involved in the pathogenesis.