Objective: To study if there is any association between frequency of HLA-DRB1 and DQB1 genes and susceptibility or resistance to Helicobacter pylori (Hp) infection among children of Yi ethnic group in Kunming for understanding the immunogenetic features of the digestive diseases associated with Hp infection.
Methods: Peripherial blood samples were collected from 156 children of Yi ethnic group in a primary school in Kunming city by cluster sampling and the blood Hp-IgG tests (ELISA) were performed. The samples were divided into two groups (Hp-IgG-positive group and Hp-IgG-negative group) according to the blood Hp-IgG test results. There were 61 children in Hp-IgG-positive group and 95 children in Hp-IgG-negative group. Forty children who were chosen from each group by simple random sampling underwent (13)carbon-urea breath test ((13)C-UBT). Thirty-three children who were Hp-IgG-positive and (13)C-UBT-positive were defined as currently Hp- infected group; 39 children who were Hp-IgG-negative and (13)C-UBT-negative were defined as Hp-non-infected group. DNA specimens were extracted from the lymphocytes of their peripheral blood samples. HLA-DRB1 and DQB1 DNA typing was performed by using polymerase chain reaction with sequence specific primers (PCR-SSP). HLA-DRB1, DQB1 allelic frequency distribution among currently Hp infected and non-infected children was compared.
Results: HLA-DRB1 * 12 gene frequency among children in Hp non-infected group was higher than that in the currently Hp-infected group (42.31% vs. 14.52%, P < 0.001, Pc < 0.012); however, HLA-DRB1 * 11 gene frequency in the Hp-non-infected group was lower than that in the currently Hp-infected group (3.85% vs. 12.9%, P < 0.05, Pc > 0.05). HLA-DQB1 * 0301 gene frequency in the Hp non-infected group was higher than that in the currently Hp-infected group (55.13% vs. 32.26%, P < 0.007, Pc < 0.05); however, HLA-DQB1 * 04 gene frequency in the Hp non-infected group was lower than that in currently Hp infected group (2.56% vs. 11.29%, P < 0.05, Pc > 0.05).
Conclusions: HLA-DRB1 * 12 and HLA-DQB1 * 0301 gene may be associated with protection against Hp infection in Kunming Yi ethnic group children. Further studies with larger sample size are needed to clarify if HLA-DRB1 * 11 and HLA-DQB1 * 04 are associated with susceptible gene to Hp infection.