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#25-OR
AN ALGORITHM CALCULATING KIR GENOTYPE COMPATIBILITY TO PREDICT OUTCOMES OF HEMATOPOIETIC CELL TRANSPLANTS (HCTs).
J.Y. Sun, MD, L. Gaidulis, MS, A. Dagis, PhD, M. M. Miller, PhD, R. Rodriguez, MD, D. Ikle, PhD, S. J. Forman, MD and D. Senitzer, PhD #. Duarte CA, USA, and Beckman Research Institute, 91010, City of Hope National Medical Center.

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Killer immunoglobulin-like receptors (KIRs) are expressed on NK cells and some T cells. They interact with specific HLA class I epitopes to regulate the activities of NK cells, and this may play a role in the HCT outcomes. We studied 65 patients with acute myeloid leukemia transplanted with unrelated donors between 1999 and 2003. KIR genotyping was performed by our own multiplex PCR-SSP method. Acute(a) GVHD was found in 19/25(76%) of patients absent of Bw4 versus (vs) in 24/40(60%) of patients with Bw4. The difference is not statistically significant. Only five out of 22 transplants mismatched at HLA-B or Cw loci were incompatible at KIR ligand epitope in GVH vector, with which no HCT outcomes associated significantly. It was reported that recipient KIR genotype included in the donor KIR genotype (D>R) increased incidence of aGVHD. In the D>R group of our cohort, aGVHD grade II-IV occurred in 12/15(80%) vs in 31/50(62%) of the remainder (P=0.114). We developed an algorithm to calculate KIR genotype compatibility as plus, minus and zero, based upon overall inhibitory and activating KIRs in donors and patients. 18/20(90%) of the plus-scored group had aGVHD II-IV vs 25/45(56%) of the non-plus group (P=0.005). In the other direction, aGVHD II-IV developed in 13/26(50%) of the minus-scored group vs in 30/39(77%) who were not minus (P=0.018). The difference of aGVHD prevalence between plus and minus scored groups is highly significant (P=0.0039). KIR genotype compatibility calculated by this algorithm may be a good predictor of the development of aGVHD. Analysis of a larger cohort of patients is in progress. # corresponding author.