[Analysis of Positive Results of Anti-M Unexpected Antibody in Pediatric Inpatients in Central China]

To analyze the positive rate and distribution of anti-M unexpected antibody in pediatric inpatients aged 0 to 14 years in central China.

A total of 30 049 pediatric inpatients admitted to the Second Xiangya Hospital of Central South University, Wuhan Children's Hospital and Children's Hospital Affiliated of Zhengzhou University from May 2020 to August 2022 were enrolled in this study, and relevant clinical data were collected. Blood samples from the patients were tested for blood typing and screened for unexpected antibodies. For samples that screened positive for unexpected antibodies, identification was conducted using the identification panel to determine the specificity of the antibodies. The distribution and differences of anti-M antibodies in pediatric patients of different sexes, ages, blood groups, disease types, with or without a history of blood transfusion, and across different regions were analyzed.

Among 30 049 inpatients, the positive rate of unexpected antibodies was 0.91% (273/30 049), of which the positive rate of anti-M antibodies was 0.44% (131/30 049). The positive rate of anti-M antibodies in the neonates aged 0 to < 1 month was 0.10% (5/4 881), and all of them were IgG antibodies from their mothers; The positive rate of anti-M antibodies for the group aged from 1 month to < 1 year old was 0.23% (7/3 108), with no anti-M antibodies detected in patients aged 1-6 months; The positive rates of anti-M antibodies in the 1-4 years old group, 5-9 years old group, and 10-14 years old group were 0.87% (88/10 064), 0.38% (27/7 190), and 0.08% (4/4 806), respectively. The positive rate of anti-M antibodies in the 1-4 years old group was significantly higher than that of the other groups ( P <0.001), and there were also statistical differences in the positive rate between the 5-9 years old group and the 0-< 1 month and 10-14 years old groups ( P <0.001). The prevalences of anti-M antibodies in ABO blood group A, B, O and AB were 0.32% (30/9 482), 0.70% (58/8 293), 0.32% (31/9 595) and 0.45% (12/2 679), respectively. The prevalence of anti-M antibodies in patients with blood group B was significantly higher than that in patients with blood groups A and O ( P <0.05). The prevalences of anti-M antibodies in Hunan, Hubei and Henan was 0.18%, 0.32% and 0.71%, respectively. The prevalence of anti-M antibodies in Henan was significantly higher than that in Hunan and Hubei ( P <0.05), and the distribution showed obvious regional differences between the north and the south. There were no significant differences in the positive rate of anti-M antibodies between the children with different sexes, disease types, and with or without a history of blood transfusion (P >0.05).

This study reveals the distribution pattern of anti-M antibodies in pediatric inpatients aged 0-14 years in central China, which has reference value for the research on unexpected red blood cell antibodies in Chinese children.