Objective To study the relationship between the expression of Mycobacterium tuberculosis small heat shock protein Hsp16.3 and the apoptosis of infected mouse alveolar macrophages.Methods The laboratory mice were infected with bacterial suspension of the international standard virulent strain of Mycobacterium tuberculosis H37Rv strains (H37Rv),Hsp16.3 gene deletion mutants of the international standard virulent of Mycobacterium tuberculosis H37Rv strains(△H37Rv),or sterile saline solution (normal control)by the tail vein. After successful replication of mouse infection model in each group,we cleaved the alveolus of each group of mice and collected lavage fluid to obtain alveolar macrophages of the infected mice at days 1 ,3 ,5 ,7 ,9 ,1 1 ,1 3 and 1 5 .Then the infection status of macrophages was observed with confocal laser scanning microscopy;flow cytometry was used to detect the apoptosis rate of alveolar macrophages of the infected mice;Caspase-3 and Bcl-2 expressions were examined by Western blot.Results The apoptosis rate of Hsp16.3 gene was higher in deletion strain (△H37Rv)group and H37Rv strains (H37Rv)group than in control group.The apoptosis rate of alveolar macrophages in △ H37Rv group gradually increased,peaked at day 7 ,and then gradually decreased.It was significantly higher in H3 7 Rv group than in H3 7 Rv strain group from day 1 to 7 and from day 1 3 to 1 5 (P<0 .0 5 ).Caspase-3 and Bcl-2 protein expressions in the macrophages of△H37Rv group and H37Rv group were higher than those of control group.Caspase-3 expression in the microphages of △H3 7 Rv group and H3 7 Rv group gradually increased from day 1 to 7 and peaked at day 7;it peaked again at day 13 in H37Rv group.However,Caspase-3 expression remained significantly higher in△H37Rv group than in H3 7 Rv group (P<0 .0 5 ).Bcl-2 expression in △H3 7 Rv group did not change much at the early stage of infection (P<0 .0 5 ),but gradually increased after day 9 .Bcl-2 expression in H3 7 Rv group did did not change much from day 1 to 7 (P<0.05),but gradually increased after day 7.However,it remained lower in△H37Rv group than in H37Rv group,especially after 7 days(P<0.05).Conclusion Mycobacterium tuberculosis small heat shock protein Hsp16.3 can inhibit the apoptosis of macrophages during the early and late stages of infection,and this inhibition may be achieved by inhibiting the expression of apoptotic protease Caspase-3 and promoting the expression of Bcl-2 protein.