OBJECTIVE: To study the expression of perforin and granzyme B (GzmB) in the lungs of asthmatic rats and the effect of recombinant human growth hormone (rhGH) on the expression. METHODS: Thirty Sprague-Dawley male rats were randomly divided into a normal control group and asthma groups with and without rhGH treatment. An asthma model was prepared by repeated sensitization with ovalbumin and aluminium hydroxide. The morphological changes of the airway were observed by hematoxylin and eosin staining. Terminal deoxyribonucleotide transferase-mediated Dutp-bintin (TUNLE) was used to detect the apoptosis of epithelial cells in the airway. RT-PCR was used to detect the mRNA transcripts of perforin and GzmB in the lung tissues. RESULTS: A significantly increased apoptosis rate of airway epithelial cells was noted in the untreated asthma group. The apoptosis rate was significantly ruduced in the rhGH-treated asthma group (P<0.05). Compared with the control group, perforin and GzmB expression in the lungs in the untreated asthma group increased significantly. The rhGH-treated asthma group demonstrated significantly decreased perforin (0.48±0.08 vs 0.63±0.08; P<0.05) and GzmB (0.44±0.13 vs 0.71±0.15; P<0.05) expression in the lungs compared with the untreated asthma group. Both PFP (r=0.800, P<0.05) and GzmB (r=0.806, P<0.01) were positively correlated with the apoptosis rate of airway epithelial cells. CONCLUSIONS: Perforin and GzmB may play important roles in the pathogenesis of asthma. rhGH treatment can inhibit apoptosis of airway epithelial cells and airway remodeling, possibly through a reduction in perforin and GzmB expression.