Rationale: In idiopathic bronchiectasis, lung inflammation and chronic bacterial infection lead to progressive lung damage. A possible role for natural killer (NK) cells is suggested by the observation that familial bronchiectasis occurs in a rare group of individuals with impaired HLA class I expression and consequent NK cell dysfunction.
Objective: Because the HLA-C locus and killer cell immunoglobulin-like receptors (KIRs) are of key importance for NK cell recognition, we analyzed HLA-C/KIR combinations by genotyping patients with idiopathic bronchiectasis.
Methods: Genomic DNA from 96 individuals with idiopathic bronchiectasis and 101 control subjects was analyzed by polymerase chain reaction with sequence-specific primers. High-resolution HLA-C genotyping was performed in addition to KIR analysis.
Results: HLA-Cw*03 alleles and, in particular, HLA-C group 1 homozygosity are associated with the presence of bronchiectasis. Analysis of the relationship between HLA-C and KIR genes suggests a shift to activatory NK cell function.
Conclusion: This is the first demonstration of genetic susceptibility in idiopathic bronchiectasis. The association with HLA-C group 1 homozygosity, and the interplay between HLA-C and KIR genes, argue for a role for NK cells in the progressive lung damage seen in this disease. This will require further investigation using functional studies.