Abstract: BACKGROUND AND AIM: To evaluate the expression of cell proliferation and apoptosis in congenital pulmonary cyst and investigate their effects in the development of congenital pulmonary cyst. MATERIALS AND METHODS: Immunohistochemical method was used to measure the expressions of Ki-67、Bcl-2 and Bax in normal lung tissue from 5 children(control group 1)，relative normal lung tissue around the cyst from 5 patients with congenital pulmonary cyst(control group 2)and abnormal lung tissue from 30 with congenital pulmonary cyst. RESULTS: The expressions of Ki-67,Bax and the ratio of Bax/Bcl-2 in congenital pulmonary cyst were significantly higher than those in the two control groups(P<0.05)while the expression of Bcl-2 was markedly lower(P<0.01).In those with congenital pulmonary cyst, the expressions of Bax and Bcl-2 in ciliated epithelial cells(CEC) were much lower than that in non-ciliated epithelial cells (P<0.01) while the ratios of Bax/Bcl-2 was much higher (P<0.01). CONCLUSION: Cell proliferation and apoptosis in congenital pulmonary cyst were significantly higher than those in control groups. This indicated that the imbalance of both could play important roles in the development of congenital pulmonary cyst.

Key words: Ki-67, Bcl-2, Bax, congenital pulmonary cyst, Immunohistochemistry