Objective To study the changes in serum immunoglobulin levels in children with thalassemia who undergo repeated blood transfusions and explore their correlation with delayed hemolytic transfusion reactions(DHTR).Methods Serum samples from children with thalassemia who received blood transfusion treatment from June 2022 to April 2023(ob-servation group)and healthy children who underwent physical examination(control group)in our hospital were collected.The levels of serum immunoglobulins(IgG subtype,IgM,IgA,IgE and IgD)were detected using flow cytometry CBA multi-factor quantitative detection technology,and the differences between the two groups were compared.The children were divided into 4 groups according to different transfusion numbers:≤10 numbers,11-30 numbers,31-50 numbers and＞50 numbers,and the differences between different blood transfusion numbers and serum immunoglobulin levels in each group were compared using one-way analysis of variance(ANOVA).Children with thalassemia with DHTR were in the hemolysis group,and children with thalassemia who did not experience DHTR were in the non-hemolysis group.The changes in serum immunoglobulins(IgG subtypes,IgM,IgA,IgE and IgD)between the two groups were compared to explore the correlation between serum immunoglobulins in thalassemia children with repeated transfusion and DHTR.Results The levels of IgG1,IgG3,IgG4 and IgA in the observation group were significantly higher than those in the control group,with the increase of(2.07±2.12),(0.67±2.03),(0.30±0.37)and(6.04±11.40)mg/mL,respectively,while the level of IgD in observation group was significantly lower than that in the control group,with a decrease of(0.03±0.01)mg/mL,P＜0.05.No significant difference was noticed in IgG2,IgM and IgE between the groups(P＞0.05).IgG1 and IgG4 both significantly increased with the number of blood transfusions.The IgG1 in the 4 groups increased sequentially as(0.30±0.62),(0.41±0.51)and(3.60±3.48)mg/mL,and IgG4 increased sequentially as(0.12±0.13),(0.22±0.07)and(0.21±0.38)mg/mL.IgG2,IgM and IgD showed a significant decrease,with IgG 2,IgM,and IgD in four groups decreased as(0.91±1.50),(0.14±0.10)and(0.05±0.05)mg/mL,respectively,showing significant differences with the number of blood transfusions(P＜0.05).No sig-nificant difference was found in IgG3,IgA and IgE with different number of transfusions(P＞0.05).IgG1,IgG3 and IgG4 in the hemolysis group were significantly higher than those in the non-hemolysis group,with an increase of(4.44±3.41),(0.73±1.26)and(0.52±0.40),respectively(P＜0.05).IgD in the hemolysis group was significantly lower than that in the non-hemolysis group,with a decrease of(0.00±0.06)mg/mL,P＜0.05.No significance was noticed in IgG2,IgM,IgA and IgE between the hemolysis group and the non-hemolysis group(P＞0.05).Conclusion The serum immunoglobulin levels of children with thalassemia who undergo repeated blood transfusions are abnormal.There are differences in correlation between the number of blood transfusions and serum immunoglobulin levels among children with thalassemia who undergo repeated blood transfusions.The relevant serum immunoglobulins for DHTR in children with thalassemia who undergo repeated blood transfusions are IgG1,IgG3 and IgG4.

[Objective] To compare the characteristics of platelet-rich plasma derived exosomes (PRP-Exos) under different activation conditions and their differential effects on the proliferation capacit of human microvascular endothelial cells (HMEC-1) and human skin fibroblasts (BJ). [Methods] Ten healthy volunteers were recruited, and 10 mL of venous blood anticoagulated with EDTA-K2 was collected. PRP-Exos were prepared and extracted by the secondary centrifugation method. Transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blotting (WB) detection techniques were used to compare the morphological characteristics, particle size distribution, concentration, and the expression of surface marker proteins of PRP-Exos. Through in vitro cell culture, the differences in morphological changes and proliferation abilities of HMEC-1 and BJ cells induced by PRP-Exos in different activator groups were compared. [Results] 1) TEM observation showed that the morphologies of PRP-Exos in different activator groups were different. 2) NTA analysis showed that compared with the particle size of (109.60±2.71) nm in the normal saline group, the particle sizes of the thrombin group [(104.93±1.55) nm] and the mixed agent group [(103.83±1.58) nm] were relatively smaller, while the particle size of the calcium gluconate group [(113.57±4.70) nm] was larger and its particle size distribution range was wider. There were statistically significant differences among different groups (F=7.019, P<0.05). The concentration of exosomes obtained in the group with the mixture of calcium gluconate and thrombin was the highest [(4.87±0.63)×10⁶ particles/mL, P<0.001]. Both the thrombin group [(2.75±0.13)×10⁶ particles/mL, P < 0.01] and the calcium gluconate group [(3.82±0.06)×10⁶ particles/mL, P<0.001] obtained higher concentrations of exosomes compared with the normal saline group. The concentration in the calcium gluconate group was slightly higher than that in the thrombin group, and there was a significant difference between the two groups (P<0.05). 3) WB analysis showed that CD41, CD81, and TSG101 were expressed on the surface of PRP-Exos, and the protein signal intensities of CD41 and TSG101 in the group with the mixture of thrombin and calcium gluconate were the strongest (P<0.001). 4) The results of in vitro cell culture showed that PRP-Exos in the group with the mixture of thrombin and calcium gluconate could significantly promote the proliferation of HMEC-1 and BJ cells (P<0.05). [Conclusion] The PRP treated with the thrombin and calcium gluconate mixture group yielded the highest concentration of exosomes; under in vitro culture conditions, PRP-Exos from this group significantly promoted the proliferation of HMEC-1 and BJ cells.

【Objective】 To share the experience of autologous platelet-rich plasma(PRP) combined therapy in successful treatment of refractory osteomyelitis with fractures in children. 【Methods】 One case of refractory osteomyelitis with fracture in children failed to respond to traditional treatment for more than 14 months. A total of 20 mL of whole blood was collected from the child, and 6 mL of PRP with 4 to 5 times concentration was prepared by secondary centrifugation. To prepare 2 cm×2 cm platelet concentrate gel (PG), 3 mL of PRP was mixed with a 0.3 mL activator which was then covered with an absorbable dressing. A three-way tube sprayed the remaining 3 mL of PRP and 0.3 mL activator into the surrounding tissues. 【Results】 The X-ray film of the patient followed up for 1 week showed that the fracture line was blurred, and the fracture end had obvious callus formation. The X-ray film reexamination at 4 months showed that the fracture end healed well, the fracture surface healed, and the osteomyelitis healed. 【Conclusion】 Autologous PRP has a good effect in the treatment of refractory osteomyelitis combined with fracture in children, which can provide a new method for clinical treatment.