Human leukocyte antigen (HLA) associations,antibody titers and circulating immune complexes in patients with cystic echinococcosis

Cystic echinococcosis (CE), caused by the parasite Echinococcus granulosus, is a prominent disease in Lebanon. The objectives of this study were to determine HLA allele-CE association in patients, and relate its presence to high anti-Echinococcus antibody titers and the presence of circulating immune complexes (CIC). Thirty patients and 20 controls were included. HLA profiles were determined by DNA-SSP typing. Relative risk and P-values were determined for each allele using Statcalc (EpiInfo, Version 6). Linkage disequilibrium was determined for associated alleles using SPSS 12.0 for Windows. Antibody titers were determined by indirect hemagglutination (IHA) and CIC by polyethylene glycol (PEG) precipitation. HLA-B*14 and HLA-DRB1*01 appeared to associate with protection against CE (P1 = P2 = 0.007 and P1 = P2 = 0.0007, respectively). However, it appeared that linkage disequilibrium did not exist between these 2 alleles (P = 0.250). HLA-B*35 was found to associate with susceptibility to disease (RR = 1.70, P = 0.02). Twenty five patients had anti-Echinococcus antibodies and 9 patients had CICs. However, there did not appear to be a correlation between the presence of HLA-B*35 and high antibody titers, or the presence of CICs. In conclusion, 2 HLA alleles that associate with resistance and 1 that associates with susceptibility to E. granulosus infection have been identified. The joint pain reported by some of the patients might be attributed to CIC deposits.