OBJECTIVETo study the biological function of killer cell immunoglobulin-like receptor (KIR) and the role of donor inhibitory KIR and recipient genetic background in HLA matched unrelated hematopoietic stem cell transplantation (HSCT).

METHODSHLA genotype of 51 patients (ALL 18 cases, CML 15 cases, AML 10 cases and others 8 cases) and their respective matched unrelated donors from Database of China Marrow Registration was determined by polymerase chain reaction sequence oligonucleotide probes (PCR-SSOP) and sequence specific primers (PCR-SSP). The KIR genotype was determined by PCR-SSP.

RESULTSAll the patients and the donors expressed KIR2DL1, KIR2DL2/L3, KIR2DL4, KIR3DL2 and KIR3DL3. 96.7% individuals expressed KIR3DL1. Among them, 21.57% of KIR was completely identical, while 78.43% was not. Of the non-identical KIRs, 25.49% were the recipient's KIR genotype containing the donor's ones, and 27.45% was the donor's containing the recipient's. 74.62% of donor's KIR2DL1 lacked recipient's C2 ligand, 5.91% of donor's KIR2DL2/L3 lacked recipient's C1 ligand, 19.74% of donor's KIR3DL1 lacked recipient's Bw4 ligand and 54.91% of donor's KIR3DL2 lacked recipient's A3, A11 ligand.

CONCLUSIONKIR genotype and HLA class I antigen are inherited independently. KIR2DLI and KIR3DL2 of donors may cause alloreactivity of NK cell. The mismatch of KIR/HLA in donor-recipient plays a very important role in matched unrelated allo-HSCT. The outcome of HSCT can be better predicted by the model of the presence of KIRs on the donor' sNK cells and the absence of corresponding KIR ligand in the recipient's HLA.