Influence of HLA-DRB1 alleles on Th1 and Th2 cytokine response to Mycobacterium tuberculosis antigens in pulmonary tuberculosis

SummaryThe influence of human leukocyte antigens (HLA) on the immune response is well established. We investigated the regulatory role of HLA-DRB1 alleles on cytokine response to live M. tuberculosis and its culture filtrate antigen (CFA) in normal healthy subjects (NHS) and pulmonary tuberculosis (PTB) patients. Th1 (IFN-γ and IL-12p40), Th2 (IL-4 and IL-5), pro-inflammatory (IL-6 and IL-8) and anti-inflammatory (TGF-β and IL-10) cytokines were measured by ELISA in 72-h-old peripheral blood mononuclear cell culture supernatants from 58 NHS and 48 PTB patients. HLA-DRB1 genotyping was carried out by polymerase chain reaction and dot-blot hybridization with biotinylated sequence-specific oligonucleotide probes and detection by chemiluminescence. In response to live M. tuberculosis and CFA, significantly increased levels of IL-6, IL-8 and TGF-β and decreased IFN-γ, IL-12p40 and IL-10 were seen in PTB patients compared to NHS. We observed a significantly increased IFN-γ response in HLA-DRB1*03-positive NHS (p=0.03) and decreased IFN-γ response in HLA-DRB1*15-positive patients (p=0.04) than respective allele-negative individuals. An increased level of IL-12p40 in DRB1*10 (p=0.02) and IL-10 in DRB1*12- (p=0.03) positive NHS and an increased level of IL-6 in DRB1*04- (p=0.02) positive patients were observed. The study suggests that HLA-DRB1 alleles differentially modulate the various cytokine responses to M. tuberculosis antigens, which may influence the cellular and humoral immune responses to M. tuberculosis infection in a susceptible host.