ESTABLISHMENT OF HUMAN MINOR HISTOCOMPATIBILITY ANTIGEN-SPECIFIC CYTOTOXIC T-CELL CLONES RESTRICTED BY HLA-DR9

Cytotoxic T lymphocyte clones specific for human minor histocompatibility (hmH) antigens were generated in vitro from PBL, of a healthy female donor, which had been repeatedly stimulated with PBL MHC antigens of her healthy, genotypically identical brother (HLA type of the siblings was A11/A2 B35/B62 C(w)4/C(w) DR4.2/DR9 DQ3/DQ- DPB1*0102/DPB*0501). Two clones were obtained that had specific killing activity against PBL- or EBV-transformed B cell line (BCL) derived from stimulator, but not from autologous cells. A panel study of the killing patterns of these two clones, using various HLA phenotype BCLs (33 BCLs) generated from healthy donors as targets, revealed that these two clones killed some DR9-bearing BCLs (5 in 20 BCLs), but did not kill the remaining DR9-bearing BCLs (15 in 20 BCLs) or other DR-type BCLs (13 BCLs). Furthermore, the killing activities of these two clones were greatly inhibited by pretreatment of the target stimulator-derived BCL with anti-HLA DR mAb. It was thus concluded that these two clones recognized hmH antigens in HLA DR9 in a restricted manner.