Clinical randomized controlled trial on influence of recombinant human growth hormone on the immune function of younger children with severe burn injuries

Objective To preliminarily investigate the influence of recombinant human growth hormone (rhGH) on the immune function of younger children with severe burn injuries. Methods A total of 30 younger children with severe burn injuries, conforming to the study criteria, were admitted to our hospital from July 2016 to July 2018. They were enrolled in the prospective, randomized, double-blinded, controlled trial and divided into group rhGH [n=15, 10 boys and 5 girls, aged (22±10) months] and control group [n=15, 8 boys and 7 girls, aged (21±7) months] according to the random number table. The patients in control group received anti-shock, anti-infection, and wound caring therapies, etc. On the basis of above-mentioned treatment, the patients in group rhGH were subcutaneously injected with rhGH once every night before bedding, with a dosage of 0.2 IU·kg^-1·d^-1, from the 3rd day post injury for 7 consecutive days. Before and on the 3rd and 7th day of rhGH treatments, the fasting peripheral venous blood was collected from patients in both groups. Blood glucose level was detected by glucometer. Percentages of CD4⁺ T lymphocytes, CD8⁺ T lymphocytes, CD3⁺ T lymphocytes, CD19⁺ B lymphocytes, and ratio of CD4⁺ T lymphocytes to CD8⁺ T lymphocytes were determined by flow cytometer. Mass concentration of serum immune globulin (Ig) A, IgG, and complement C3 were detected by enzyme-linked immunosorbent assay. Data were processed with Fisher′s exact probability test, independent sample t test, analysis of variance for repeated measurement and Bonferroni correction, and Mann-Whitney U test. Results (1) The blood glucose levels of children in the two groups were similar before and on the 3rd and 7th day of rhGH treatment (t=0.474, 1.652, 1.997, P>0.05). The glucose levels of children in group rhGH on the 3rd and 7th day of rhGH treatment [(6.9±1.0) and (7.7±1.1) mmol/L] were significantly higher than (5.9±0.9) mmol/L before rhGH treatment (P<0.05). The glucose level of children in control group on the 7th day of rhGH treatment was significantly higher than that before rhGH treatment (P<0.05). (2) The percentages of CD4⁺ T lymphocytes of children in group rhGH before rhGH treatment and on the 7th day of rhGH treatment were (35.1±2.0)% and (38.5±2.2)%, which were close to (36.2±2.0)% and (33.6±2.2)% in control group, respectively (t=0.371, 1.553, P>0.05). The percentages of CD4⁺ T lymphocytes of children in group rhGH on the 7th day of rhGH treatment[(44.7±2.2)%] was significantly higher than (36.5±2.2)% in control group (t=2.624, P<0.05). The percentage of CD4⁺ T lymphocytes of children in group rhGH on the 7th day of rhGH treatment was significantly higher than that before rhGH treatment (P<0.05). The percentages of CD4⁺ T lymphocytes of children in control group on the 3rd and 7th day of rhGH treatment were both close to the percentage before rhGH treatment (P>0.05). (3) The percentage of CD8⁺ T lymphocytes of children in group rhGH on the 3rd day of rhGH treatment was significantly lower than that in control group (t=2.107, P<0.05). (4) The ratio of CD4⁺ T lymphocytes to CD8⁺ T lymphocytes of children in group rhGH on the 7th day of rhGH treatment (2.36±0.20) was significantly higher than 1.72±0.20 in control group (t=2.285, P<0.05). The ratio of CD4⁺ T lymphocytes to CD8⁺ T lymphocytes of children in group rhGH on the 7th day of rhGH treatment was significantly higher than 2.04±0.19 before rhGH treatment (P<0.05). (5) The percentages of CD3⁺ T lymphocytes and CD19⁺ B lymphocytes of children in the two groups were similar before and on the 3rd and 7th day of rhGH treatment (t=1.913, 0.552, 1.327, 1.465, 1.587, 0.407, P>0.05). The percentages of CD3⁺ T lymphocytes of children in group rhGH on the 3rd and 7th day of rhGH treatment were significantly higher than the percentage before rhGH treatment (P<0.05). (6) The mass concentration of serum IgA, complement C3, and IgG of children in the two groups was similar before and on the 3rd and 7th day of rhGH treatment (t=-1.596, -0.100, 1.263, -0.220, 1.378, 1.631, Z=0.228, 0.519, 1.182, P>0.05). The mass concentration of serum IgA and complement C3 of children in group rhGH on the 3rd and 7th day of rhGH treatment was significantly higher than that before rhGH treatment(P<0.05). Conclusions rhGH has little effect on humoral immunity of younger children with severe burn injuries with limited influence on CD19⁺ B lymphocyte, mass concentration of serum IgA, IgG, and complement C3. It may improve the cellular immunity function mainly through promoting the release of CD4⁺ T lymphocyte, reducing the release of CD8⁺ T lymphocyte. It can be used in clinical treatment of younger children with severe burn injuries.