A Study On The Association Between The Erythrocyte Complement Receptor 1 (CR1) Genomic Density Polymorphism And Erythrocyte Immune Function In Children With Recurrent Respiratory Tract Infections

Objective To explore the hereditary susceptibility of children to develop recurrent respiratory tract infections(RRTI) by studying the association between CRl genomic density polymorphism and erythrocyte immune function. Methods The subjects were composed of two groups, the patient group consisted of 38 children with RRTI;the control group was composed of 56 normal children . The rates of red cell C3b receptor rosette (RBC-C3bRR) and the rates of red cell immune complex rosette(RBC-ICR) were detected by GuoFeng's method. HindIII restriction enzyme, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), DNA sequence analysis and genetic analysis methods were used. A restriction fragment length polymorphism in an intro within the structural CRl gene on chromosome 1 was tested in both groups. The activity of the erythrocyte complement receptor 1 (CRl) and the data of the CRl gene genotypes and alleles in two groups were compared. Results The rates of RBC-C3bRR were found to be significantly lower in RRTI than those in normal children(t=4. 292, P <0. 01). The rates of RBC-ICRbetween the two groups were not difference( t=l. 419, P>0. 05). Frequencies of HH HL and LL genotypes were 34.2%, 55.3% and 10.5% in the RRTI group, however 75%. 21.4% and 3. 6% in the control group, respectively. A significant difference was found in the frequency distribution of CR1 genotype between two groups. (P <0. 001). In the patient group, HL and LL genotypes were more common than control group (0R=5. 77). Moreover, CR1 allele frequencies of HindIII polymorphism also showed significant difference between the two groups (x 2=14. 612, P <0.01), L alleles were more common in patient group than in control group. Conclusion There is an association between CR1 genomic density polymorphism and erythrocyte immune function in children with RRTI. HL and LL genotype of CR1 gene may be significantly associated with RRTI. This study suggested that Hindlll restriction enzyme cleavage site polymorphism of CR1 gene might be important in determining an individual's susceptibility to development of RRTI.