Analysis of the 8.1 ancestral MHC haplotype in severe, pneumonia-related sepsis

The most frequent Caucasian MHC haplotype, AH8.1 - associated with numerous immunopathological differences and certain autoimmune diseases - was recently linked to the delayed onset of bacterial colonization in cystic fibrosis. Based on this observation, we hypothesized that the carriers of AH8.1 have lower risk for a worse outcome in sepsis. AH8.1 carrier state was determined in 207 Caucasian patients with severe, pneumonia-related sepsis. Our data showed that in patients without chronic obstructive pulmonary disease (COPD), septic shock - a serious consequence of the bacterial infection - occurred significantly less frequently (OR=0.3383; 95% CI=0.1141-0.995; p=0.043) in carriers of AH8.1, than in non-carriers. According to the multivariate logistic regression analysis, this haplotype had an independent protective role against septic shock in all patients (OR=0.315; 95% CI=0.100-0.992; p=0.048), particularly in COPD-free patients (OR=0.117; 95% CI=0.025-0.554; p=0.007). These results indicate that AH8.1 may confer protection against the progression of bacterial infection, and this could explain, at least partially, its high frequency in the Caucasian population. (C) 2011 Elsevier Inc. All rights reserved.