To investigate the changes and clinical significance of immune function of neonates with infectious pneumonia.

Total of 60 neonates with infectious pneumonia admitted in the Department of Neonatology, the Central Hospital of Longhua District from March 2016 to October 2017 were selected as observation group, while 60 healthy newborns were selected as the control group during the same period. According to the severity of pneumonia, cases in observation group were divided into mild group (39 cases) and severe group (21 cases). According to the staging difference of neonatal infectious pneumonia, cases in observation group were divided into acute stage group (24 cases) and convalescent stage group (36 cases). The blood samples of all children were collected in acute period and recovery period, for the detection of humoral immunity indexes (IgA, IgM, IgG1, IgG2, IgG3, IgG4 and complement C3, C4) and cell immunity indexes (CD3⁺ T, CD4⁺ T, CD8⁺ T, CD4/CD8, NK cells).

The serum levels of IgA, IgG1, IgG2, IgG3, IgG4, the ratios of CD3⁺ T cells, CD4⁺ T cells, NK cell and CD4/CD8 in cases of severe group were significantly lower than those of the control group and mild group (all P < 0.05, but the ratios of IgM, C3, C4 and CD8⁺ T cells were significantly higher than those of the control group and mild group (all P < 0.05). Spearman correlation analysis showed that the levels of serum IgA, IgG1, IgG2, IgG3, IgG4, the ratios of CD3⁺ T cells, CD4⁺ T cells, NK cells and CD4/CD8 were negatively correlated with the severity of neonatal infectious pneumonia (r =-0.826, -0.826, -0.665, -0.822, -0.826, -0.816, -0.794, -0.824, -0.820; all P < 0.001). The level of serum C3 and CD8⁺ T cell ratio were positively correlated with the severity of neonatal infectious pneumonia (r = 0.467, 0.788; all P < 0.001). The levels of serum IgA, IgG1, IgG2, IgG3, IgG4, CD3⁺ T cells, CD4⁺ T cells, NK cells and CD4/CD8 of cases in the acute stage were significantly lower than those of the convalescent stage group and the control group (all P < 0.05), but the levels of serum IgM, C3, C4 and CD8⁺ T cells were significantly higher than those of the convalescent stage group and the control group, all with significant differences (all P < 0.05).

Cellular immunity and humoral immunity function of patients with neonatal infectious pneumonia declined, which were negatively correlated with the severity of disease. Diseases at different stages have great influence on immune status, which should be focused on the regulation of immune status of these neonates.