ABSTRACT
Objective To investigate the expression of CD35 on erythrocyte membrane and the changes of serum inflammatory cytokines in children with recurrent respiratory tract infection (RRTI) and their relation to zinc therapy. Methods One hundred and sixteen RRTI children including 82 cases of upper respiratory tract infection and 34 cases of lower respiratory tract infection were enrolled in the study;40 children with acute respiratory infection and 50 healthy children were randomly selected as the controls. The expression of CD35 on erythrocyte membrane, positive rate of circulating immune complex (CIC), IL-6, IL-8 and TNF-α were detected. Sixty-eight RRTI children with hypozincemia were randomly divided into zinc treatment group ( n = 38) and control group ( n = 30). The above parameters were detected at the end of the treatment and 12 weeks after the treatment. Results The expression of CD35 on erythrocyte membrane was significantly lower in RRTI children ( upper respiratory group and lower respiratory group) than that in healthy controls ( t=6.17 and 6.46, P <0.01 ). CIC-pesitive rate and the contents of IL-6, IL-8 and TNF-α were increased in RRTI children, especially in those with lower respiratory tract infections. Compared with the children of acute respiratory infections, the expression of CD35on erythrocyte memhrane was much lower in RRTI children in the remission stage ( t = 20. 307, P < 0.01 ). The above parameters were improved in RRTI children who received zinc treatment. Conclusions Down-regulation of CD35, insufficient elimination of CIC, excessive production of serum IL-6, IL-8 and TNF-α were observed in RRTI children, which might be the immunopathologic mechanism of the repeated infection. These indexes can be improved after zinc treatment.