Serologic recognition of a HLA-B44(12) subgroup associated with the 44.2 specificity defined by CML.
Several investigators have reported that subdivisions of HLA-B44, which are not defined by available cytotoxic antisera, can be detected by cytotoxic T lymphocytes. The present study was designed to evaluate two sera which appear to recognize a specificity on some HLA-B44 and B45 positive cells and to determine whether the specificity is correlated with one of the B44 subgroups which are defined by cell-mediated lympholysis. Serum BG1359, eluted from a placenta and serum Cutchember (a gift from Dr. Wilma Bias), were tested on a 23-member B44 positive cell panel. The panel was typed independently with CTLQ1/M3 (specificity 44.1) and CTLM3/Q1 (specificity 44.2). Cells classified as 44.2 usually typed positive with serums 1359 and Cutchember, whereas 44.1 cells usually were negative with these sera in the Amos modified cytotoxicity technique. In the 4th American workshop data, serologic reactivity correlated with B44 (r = 0.87 and 0.75) and B45 (r = 0.32 and 0.34) for serums 1359 and Cutchember, respectively. In a North Carolina population study (N = 155), specificity 1359 was detected in 37 of 53 (70%) of B44 positive individuals and in 5 of 6 B45 positive individuals. In three informative families, the 1359 private specificity segregated with B44 haplotypes. The 44.2 subgroup is in positive linkage disequilibrium with C4 and DR7 and possibly with A23, A26, and A29, whereas the 44.1 subgroup seems to be in disequilibrium with A2, Cw5, DR4, and DRw6.