The killer immunoglobulin-like receptor (KIR) group a haplotype is associated with bronchiolitis obliterans syndrome after lung transplantation

Background: The development of bronchiolitis obliterans syndrome (BOS) after lung transplantation is associated with viral infections. Natural killer (NK) cells are involved in the lysis of viral infected cells, and their activation is largely controlled by activating and inhibitory killer immunoglobulin-like receptors (KIRs). We hypothesized that KIR ligand incompatibility and recipients' individual KIRs could influence the development of BOS and the incidence of cytomegalovirus reactivation after lung transplantation. Methods: The KIR gene contents were determined in 48 patients who received a lung transplant, and human leukocyte antigen (HLA)-Cw and HLA-Bw4 typing was performed on their respective donors. Results: BOS developed in 7 patients and cytomegalovirus reactivation occurred in 16. BOS developed in 5 of 19 patients homozygous for KIR haplotype A compared with 2 of 27 patients with KIR haplotype AB and B (homozygous; p = 0.03; log-rank test). In none of the patients with BOS was the activating KIR2DS5 gene detected, whereas it was present in 35% of patients without BOS (p = 0.04; log-rank test). No correlation was found between KIR gene content and cytomegalovirus reactivation. Conclusion: Our results suggest that the lack of activating KIRS may play an important role in the development of BOS but not in the control of cytomegalovirus reactivation after lung transplantation.