ABSTRACT
【Objective】 To explore the effect of B lymphocytes on cardiac structure and function and myocardial immune cells during heart development. 【Methods】 Echocardiography, immunofluorescence staining and flow cytometry were used to evaluate the composition of immune cells of the heart and the cardiac structure and function in wild-type (WT) mice and B-lymphocyte-deficient (μMT) mice, respectively. 【Results】 Compared with those of μMT mice, the ratio of heart weight to mouse weight (P<0.05), left ventricular mass (P<0.05) and the cross-sectional area of myocardial cells WT mice were significantly increased, while the ventricular ejection fraction was significantly decreased (P<0.05). The results of mRNA sequencing showed that WT mice and μMT mice differentially expressed genes were mainly enriched in the signal pathway of heart development and hypertrophic cardiomyopathy. The results of flow cytometry showed that WT mice had more Ly6g+ neutrophils, CD4+ positive T cells (P<0.001) and CD8+T cells (P<0.05) compared with μMT mice. 【Conclusion】 B-lymphocyte depletion alters the composition of cardiomyocyte immune cells, reduces left ventricular mass, and increases myocardial contractility.