| Abstract: | Objective To investigate the expression of CD3 + HLA-DR in peripheral blood lymphocytes and the level of serum VitA in severe Mycoplasma pneumoniae pneumonia. Methods 24 children who met the diagnostic criteria of severe Mycoplasma pneumoniae pneumonia admitted to the pediatric ward of our hospital from January 2017 to December 2020 were analyzed retrospectively. 47 cases of common Mycoplasma pneumoniae pneumonia hospitalized in the same period were randomly selected as the general group; 23 patients with simple upper respiratory tract infection and short stature were the control group; Fasting venous blood was collected in the morning of the next day after the admission, including non anticoagulant 1ml and anticoagulant 3ml; The antibody titer of Mycoplasma pneumoniae was determined by micro blood passive agglutination method, CD19, CD4, CD8, CD3 + HLA-DR was determined by American Berman flow cytometry and reagent, and serum VA was detected by high performance liquid chromatography; Statistical analysis: one-way ANOVA was used, and LSD-t test was used for pairwise comparison; Pearson analysis was used for correlation analysis; The risk factors were analyzed by logistic analysis. Results 1. There were 24 cases of severe Mycoplasma pneumoniae pneumonia, 14 males and 10 females, aged （4.97 ± 1.79） years; There were 47 cases of Mycoplasma pneumoniae pneumonia, 30 males and 17 females, with an average age of （4.87 ± 1.79） years; In the same period, there were 23 hospitalized children with simple upper respiratory tract infection and short stature, including 12 males and 11 females, with an average age of （4.77 ± 2.11） years. There was no significant difference in age and gender among the three groups （P > 0.05）; 2. Comparison of CD19, CD4, CD8, CD3 + HLA-DR and vita values among the three groups: the expression of CD4, CD3 + HLA-DR and serum Vita levels in lymphocytes of the severe group were significantly lower （34.2 ± 4.54, 11.83 ± 2.57, 0.23 ± 0.10）, CD19 （18.66 ± 2.56） increased significantly, which was significantly higher than that in the general group 38.1 ± 4.04, 17.11 ± 2.71, 0.33 ± 0.14] and the control group （39.35 ± 3.86, 18.78 ± 1.86, 0.40 ± 0.14） （P < 0.05）; Vita was positively correlated with CD4, CD3 + HLA-DR （r = 0.371, 0.688, P < 0.05）. The results of logistic regression analysis showed that the decrease of serum Vita level and CD3 + HLA-DR expression were independent risk factors of SMMP （or = 4.42, 2.38, P < 0.05）. Conclusion lymphocyte activation was involved in the occurrence and development of MPP. Excessive immune response would not only induce excessive immune response, but also lead to autoimmune injury （immune paralysis）. It is speculated that VitA is also involved in regulating lymphocyte activation. |
