Definition of LD “4 × 7”: A unique HLA-D specificity defined by two homozygous typing cells

Abstract

Two homozygous typing cells (HTC) from the Eight International Histocompatibility Workshop were used to define a unique HLA-D specificity, designated LD “4 × 7”. Typing cell 8W316 (Seattle) was obtained from a donor of Japanese descent: cell 8W324 (Leiden) was obtained from a European Caucasian donor. The HLA-D specificities defined by these two HTC showed a significant correlation (r = 0.65) i unselected panel studies and clear segregation as a single determinant within families. LD “4 × 7” was found in low frequency in Caucasians (1.0%) but was detected with a frequency of 24% in Japanese. The cells of the donors of HTC 8W316 and 8W324 express DRw9, and the LD “4 × 7” antigen fills an HLA-D locus “blank” on DRw9-positive haplotypes. The frequency of LD “4 × 7” noted in this study corresponds to the frequency of DRw9 reported for Japanese and Caucasian ethnic groups, a further indication that LD “4 × 7” and DRw9 are associated.