Rapid HLA class I DNA typing using microtiter plate-reverse hybridization assay (MRHA) by simple thermoregulation: high-resolution subtyping of the HLA-A2 and -B40 antigen groups

Short communication: association of HLA-A*1101 with resistance and B*4006 with susceptibility to HIV and HIV-TB: an in silico analysis of promiscuous T cell epitopes

We have shown the association of HLA-A*11 with resistance and HLA-B*40 and -DR2 with susceptibility to HIV and HIV-TB. In the present study, we performed high-resolution subtyping of HLA-A*11 and -B*40 to identify the subtype level association, using the polymerase chain reaction-based sequence-specific oligonucleotide probe method. Underrepresentation of HLA-A*1101 was observed in overall HIV [p(c) = 0.012, OR 0.42 (95% confidence interval (CI) 0.24-0.72)] and HIV(+)TB(+) [p(c) = 0.001, OR 0.18 (95% CI 0.06-0.46)] compared to healthy controls. Significantly higher frequencies of HLA-B*4006 were observed in overall HIV [p = 0.0001, p(c) = 0.004, OR 2.71 (95% CI 1.58-4.75)], HIV(+)TB(-) [p = 0.0003, p(c) = 0.008, OR 2.82 (95% CI 1.56-5.17)], and HIV(+)TB(+) [p = 0.003, p(c) = 0.086, OR 2.56 (95% CI 1.33-4.95)] compared to healthy controls. An in silico analysis of potential T cell epitopes of consensus Gag and Pol sequences of HIV-1 subtype C Indian strains revealed relatively higher number of promiscuous HLA-B40, HLA-DRB1*1501, and -DRB1*1502 (HLA-DR2)-restricted epitopes in contrast to limited numbers of promiscuous binders restricted by HLA-A*1101. The results suggest that HLA-A*1101 may be associated with protection against HIV and the development of TB in HIV patients while HLA-B*4006 may be associated with susceptibility to HIV and TB development in HIV patients. The present study also suggests that the extent of promiscuity of T cell epitopes of HIV-1 subtype C restricted by HLA alleles exerting opposing effects might differ.

Rapid and simultaneous HLA class I (-A, -B and -C loci) DNA typing using the microtitre plate-reverse hybridization assay (MRHA)

We have established a precise, rapid, simple and practical HLA class I DNA typing method using the microtitre plate-reverse hybridization assay (MRHA), which enables us to perform simultaneous DNA typing of the HLA-A, -B and -C loci using the same PCR parameters and hybridization conditions. PCR-amplified products for the HLA-A, -B and -C loci were hybridized, respectively, with sequence-specific oligonucleotide (SSO) probes, which were immobilized covalently onto a microtitre plate, in hybridization buffer containing formamide at 37 degrees C. After washing at room temperature, the bound PCR products were detected by peroxidase-conjugate streptavidine followed by colour development such as enzyme immunoassay (EIA). In addition to the simple thermoregulation for hybridization and postwashing, strong positive signals, low background and high reproducibility, this DNA typing method enabled simultaneous typing of the HLA-A, -B and -C loci using a single microtitre plate as in HLA serotyping. The assignment of the HLA genotype was easily achieved by automated colorimetric reading and computer software, based on the cut-off value (threshold) established for each probe. For routine HLA class I typing, it may be possible to replace serological typing with the HLA class I DNA typing system using our MRHA method.

Somatic cell mutation in pediatric patients undergoing allogeneic bone marrow transplantation

In order to examine whether bone marrow transplantation (BMT) has genotoxic effects in vivo, mutant frequencies (Mfs) at the hypoxanthine-guanine phosphoribosyl transferase (Hprt) locus were evaluated. Thirty-seven pediatric patients who had received allogeneic BMT for various hematologic or immunologic disorders were enrolled. Nine out of the 37 patients (24.3%) were found to have Hprt-Mfs exceeding the 99% confidence limits calculated from observation of healthy controls. Among factors including gender, primary disease of the patient, donor-recipient histocompatibility relationship, age of donor, and total body irradiation as conditioning regimen, none was associated with an increased Hprt-Mf. In three patients who had chimerism in their peripheral blood after BMT, Hprt mutant clones turned out to be of donor- or recipient-origin. Mfs at the T-cell receptor (TCR) locus were examined in 28 patients. Four patients (14.3%) were found to have increased TCR-Mfs. However, there were not any patients who showed elevation of both Hprt-and TCR-Mfs. These data, taken together, suggest that BMT may cause genotoxicity in vivo in some patients.