No abstract

Alleles of HLA-A, B, C, DRB1, DQB1, and DPB1 loci were fully determined in 117 healthy Japanese. A*2402, A*3303, A*1101, A*0201, B*4403, B*5201, Cw*0102, Cw*1403, Cw*0304, Cw*0702, Cw*0801, and Cw*1202 showed frequencies of over 10%. Multi-locus haplotype frequencies were estimated by the maximum likelihood method. Strength of association between C and B loci was comparable with that between DRB1 and DQB1 loci. Alleles unidentified by a serological method and having very similar nucleotide sequences (A2: A*0201, A*0206, A*0207, B61: B*4002, B*4006) were carried by different haplotypes. Several frequent five-locus haplotypes were identified including A*3303-Cw*1403-B*4403-DRB1(*)1302-DQB1(*)0604, and A*2402-Cw*1202-B*5201-DRB1(*)1502-DQB1(*)0601. These sequence-based haplotypes corresponded to serology-based common haplotypes which have already been described in Japanese. These findings indicate that common HLA haplotypes consist of particular sets of HLA alleles and that these haplotypes have been conserved through recent human evolution.

The present study investigates the human leucocyte antigen (HLA) allele and haplotype frequencies in Japanese population. We carried out the frequency analysis in 5824 families living across Japanese archipelago. The studied population has mainly been typed for the purpose of transplant, especially the hematopoietic stem cell transplantation (HSCT). We determined HLA class I (A, B, and C) and HLA class II (DRB1) using Luminex technology. The haplotypes were directly counted by segregation. A total of 44 HLA‐A, 29 HLA‐C, 75 HLA‐B, and 42 HLA‐DRB1 alleles were identified. In the HLA haplotypes of A‐C‐B‐DRB1 and C‐B, the pattern of linkage disequilibrium peculiar to Japanese population has been confirmed. Moreover, the haplotype frequencies based on family study was compared with the frequencies estimated by maximum likelihood estimation (MLE), and the equivalent results were obtained. The allele and haplotype frequencies obtained in this study could be useful for anthropology, transplantation therapy, and disease association studies.

To identify critical events associated with heat-induced cell killing, we examined foci formation of ␥H2AX (histone H2AX phosphorylated at serine 139) in heat-treated cells. This assay is known to be quite sensitive and a specific indicator for the presence of double-strand breaks. We found that the number of ␥H2AX foci increased rapidly and reached a maximum 30 minutes after heat treatment, as well as after X-ray irradiation. When cells were heated at 41.5°C to 45.5°C, we observed a linear increase with time in the number of ␥H2AX foci. An inflection point at 42.5°C and the thermal activation energies above and below the inflection point were almost the same for cell killing and foci formation according to Arrhenius plot analysis. From these results, it is suggested that the number of ␥H2AX foci is correlated with the temperature dependence of cell killing. During periods when cells were exposed to heat, the cell cycledependent pattern of cell killing was the same as the cell cycle pattern of ␥H2AX foci formation. We also found that thermotolerance was due to a depression in the number of ␥H2AX foci formed after heating when the cells were pre-treated by heat. These findings suggest that cell killing might be associated with double-strand break formation via protein denaturation.

Human γδ T cells bearing Vγ2Vδ2-TCR recognize various kinds of small nonpeptide Ags, and activation of them by a nitrogen-containing bisphosphonate Ag, pamidronate, requires Ag presentation by cells other than γδ T cells, including many human tumor cells. Present results demonstrated that tumor cell lines of nonhuman origins pulsed with pamidronate failed to activate human γδ T cells without exception, whereas most if not all human tumor cell lines could do so. γδ T cells formed stable conjugates with pamidronate-pulsed human tumor cells and both conjugate formation and γδ T cell activation were inhibited significantly by anti-LFA-1 mAb, suggesting the requirement of LFA-1-mediated interaction with APC for efficient γδ T cell activation. Consistently, ICAM-1low tumor cell lines pulsed with pamidronate induced no or only weak activation of γδ T cells, whereas similarly treated ICAM-1high cell lines could activate them. One of the two ICAM-1low tumor cell lines pulsed with pamidronate induced strong γδ T cell activation after ICAM-1 gene transfer. However, another ICAM-1low human cell line as well as murine tumor cell lines pulsed with pamidronate remained totally defective in γδ T cell activation even after expression of human ICAM-1. These results suggested that activation of human γδ T cells by nonpeptide Ags required species-specific interactions in addition to LFA-1/ICAM-1-mediated cell adhesion with APC.