Cerebral malaria is a major, life-threatening complication of
Plasmodium falciparum malaria, and has very high mortality rate. In murine
malaria models, natural killer (NK) cell responses have been shown to play a crucial role in the pathogenesis of
cerebral malaria. To investigate the role of NK cells in the developmental process of human
cerebral malaria, we conducted a case-control study examining genotypes for killer
immunoglobulin-like
receptors (KIR) and their
human leukocyte antigen (HLA) class I
ligands in 477
malaria patients. We found that the combination of KIR2DL3 and its cognate HLA-C1
ligand was significantly associated with the development of
cerebral malaria when compared with non-
cerebral malaria (odds ratio 3.14, 95% confidence interval 1.52-6.48, Pā=ā0.00079, corrected Pā=ā0.02). In contrast, no other KIR-HLA pairs showed a significant association with
cerebral malaria, suggesting that the NK cell repertoire shaped by the KIR2DL3-HLA-C1 interaction shows certain functional responses that facilitate development of
cerebral malaria. Furthermore, the frequency of the KIR2DL3-HLA-C1 combination was found to be significantly lower in
malaria high-endemic populations. These results suggest that natural selection has reduced the frequency of the KIR2DL3-HLA-C1 combination in
malaria high-endemic populations because of the propensity of interaction between KIR2DL3 and C1 to favor development of
cerebral malaria. Our findings provide one possible explanation for KIR-HLA co-evolution driven by a microbial pathogen, and its effect on the global distribution of
malaria, KIR and HLA.