Mannose-binding lectin concentrations, MBL2 polymorphisms, and susceptibility to respiratory tract infections in young men.

Abstract

Mannose-binding lectin (MBL) is an important component of innate immunity, and its deficiency is associated with susceptibility to recurrent infections. This exploratory study investigated the association of serum MBL concentrations and MBL2 gene polymorphisms with respiratory tract infections in young men. We genotyped 6 single-nucleotide polymorphisms (SNPs) in the promoter region (alleles H/L, X/Y, and P/Q) and exon 1 (variant alleles B, C, and D and wild-type allele A) of the MBL2 gene by real-time polymerase chain reaction and measured serum MBL concentrations in 111 Finnish military recruits with asthma and 362 without. An MBL level below the median concentration was a significant risk factor for infections (asthma status-adjusted odds ratio [OR], 2.5 [95% confidence interval {CI}, 1.4-4.5]). Among the 6 SNPs, there was a significant association between the promoter Y/Y genotype and infections (OR, 2.3 [95% CI, 1.2-4.4]) and a borderline significant association between exon 1 variant alleles and infections (OR, 1.7 [95% CI, 0.9-3.1]), after adjustment for asthma status. These preliminary results suggest, for the first time, an association between MBL level and respiratory tract infections in young men and a possible association between infections and MBL2 polymorphisms.