OBJECTIVETo investigate the effect of inhibitory and activating KIRs on a cohort of Chinese leukemia patients who received haplo-identical hematopoietic stem cell transplantation (HSCT).

METHODSDonor's inhibitory and activating KIRs and recipient's HLA-C from 47 cases who received haplo-identical HSCT were tested by PCR-SSP. 2 year overall survival (OS), incidence of severe (grade III to IV) acute GVHD (aGVHD) and relapse rate (RR) were analyzed.

RESULTS(1) According to Matched (M) vs Mis-Matched (MM) between donor's inhibitory KIR and recipient's HLA-C1/C2 subgroup, 2 year OS rate in M group [(87.5 +/- 8.3)%] was significantly higher than that in MM group (54.5 +/- 9.0)%, (P = 0.03). Lower incidence of relapse rate was seen in M group than in M/MM groups [0 vs (25.4 +/- 9.5)%, P = 0.05]. In 30 cases of myeloid leukemia patients, there was lower RR in M group than in MM groups [0 vs (35.0 +/- 14.4)%, P = 0.04]. (2) According to the 3 activating KIR genes: KIR2DS1/ KIR2DS2/ KIR2DS3, lower incidence of grade III-IV aGVHD was seen in KIR2DS1 (+) group than in KIR2DS1 (-) group (13% vs 28%, respectively, P > 0.05); and so was done in KIR2DS3 (+) group (11% vs 26%, respectively, P > 0.05). The RR was lower in KIR2DS2 (+) group [0% vs (17.3 +/- 7.1)%, respectively, P > 0.05].

CONCLUSIONSIn our haplo-identical HSCT setting, match between donor's inhibitory KIR and recipient's HLA-C can significantly reduce the incidence of relapse rate and improve OS. Although lower incidences of severe aGVHD are noted in the donors with KIR2DS1 (+) or KIR2DS3 (+), and lower relapse rate is noted in the donors with KIR2DS2 (+) but without statistic difference, no remarkable effects of activating KIRs on OS have been found in our relatively small clinical series.