Diversity within the DRB1*08 allele family in four populations from a United States hematopoietic stem cell donor database and characterization of five novel DRB1*08 alleles

The shared epitope hypothesis in rheumatoid arthritis: evaluation of alternative classification criteria in a large UK Caucasian cohort

OBJECTIVE

Many classification systems for the HLA-DRB1 allelic association with rheumatoid arthritis (RA) have been reported, but few have been validated in additional populations. We sought to evaluate 3 different DRB1 allele classification systems in a large cohort of Caucasian RA patients and control subjects in the UK.

METHODS

HLA-DRB1 typing was undertaken in 1,325 Caucasian RA patients and 462 healthy Caucasian controls who were residents of the UK. Logistic regression analyses were performed to investigate the different classification systems.

RESULTS

We confirmed the association between the susceptibility alleles S2 and S3P, as proposed by Tezenas du Montcel, and the presence of RA in UK Caucasians. A significant hierarchy of risk was observed within the S3P allele group. There was no evidence of a significant association between DRB1*1001 and RA. Our data did not support the hypothesis that an isoleucine at position 67 conferred protection against RA, other than in contrast to the susceptibility alleles. However, the presence of an aspartic acid at amino acid 70 did appear to confer some degree of protection.

CONCLUSION

We were unable to fully substantiate any of the 3 recent revisions of the shared epitope hypothesis in this large cohort of Caucasian RA patients and control subjects in the UK. This reinforces the importance of evaluating disease susceptibility alleles in different Caucasian populations as well as in other ethnic groups. In particular, it will be important to clarify the precise DRB1 association in a given population before DRB1 genotyping is incorporated into clinical diagnostic or treatment algorithms.

Searching for HLA-DRB1*1206 in volunteer marrow donors in four US population groups

The frequencies of DRB1*12 alleles were determined in four US population groups by DNA sequencing. Only DRB1*120101 (or DRB1*1206 or *1210) and DRB1*120201 alleles were identified, the latter primarily in the Asian American population. Additional testing of a subset of samples to detect the presence of DRB1*1206 found all of the alleles to be DRB1*120101 (or DRB1*1210). Retesting of six samples previously typed as DRB1*1206 found only DRB1*120101 (or DRB1*1210).

Prediction of crossmatch outcome of highly sensitized patients by single and/or multiple antigen bead luminex assay

BACKGROUND

We used a solid-phase assay to identify human leukocyte antigen (HLA) Class I and II specificities in highly reactive sera, and applied this information to predict crossmatch outcome with greater than 90% accuracy.

METHODS

Sera from 20 highly sensitized end-stage renal disease patients reactive to 70-100% of HLA Class I and II antigen panel were analyzed by single and/or multiple antigen flow microparticle bead assay using Luminex platform (Luminex assay). These sera contained antibodies directed against high frequency public HLA class I and/or II epitopes accounting for 70-100% of serum's total reactivity. More than 2,000 complement dependent cytotoxicity (CDC) and 200 flow crossmatches (FLXM) were performed using sera from these patients and deceased donor T and B lymphocytes.

RESULTS

Luminex serum analysis was able to correctly predict outcomes of 95% of T and B cell FLXM. In contrast, predictive values for the CDC T and B cell crossmatches by Luminex serum analysis were only 77% and 75%, respectively. The use of serum analysis in donor selection would have reduced the total number of required FLXM by more than 50%. The frequency of negative T cell FLXM was 56% when donors were selected randomly; however, if serum antibody analysis had been used to preselect the donors by excluding donors that were likely to be positive, the frequency of corresponding negative crossmatches would have increased up to 93%.

CONCLUSION

This approach to donor selection may allow wider geographic sharing of cadaver donor organs without actually performing the crossmatch.

Group-specific amplification of cDNA from DRB1 genes. Complete coding sequences of partially defined alleles and identification of the new alleles DRB1*040602, DRB1*111102, DRB1*080103, and DRB1*0113

We present here the complete coding sequences, previously unavailable, of the DRB1 alleles DRB1*030102, *0306, *040701, *0408, *1327, *1356, *1411, *1446, *1503, *1504, *0806, *0813, and *0818. For cDNA isolation, new group-specific primers located at the 5'UT and 3'UT regions were used to carry out allele-specific amplification and a convenient method for determining full-length sequences for DRB1 alleles. Complete coding sequencing of samples previously typed as DRB1*0406, DRB1*080101, and DRB1*1111 revealed new alleles with noncoding nucleotide changes at exons 1 and 3. In addition, we found a novel allele, DRB1*0113, whose second exon carries a sequence motif characteristic of DRB1*07 alleles. The predicted class II haplotypic associations of all alleles are reported and discussed.