The results showed that B-cell deletion reduced the expression of the cytokines TNF-α, IL-1β, IL-6, and TGF-1β, decreased myocardial collagen synthesis after AMI, alleviated myocardial fibrosis, improved left ventricular remodelling, and maintained the left ventricular ejection fraction. The gene discussed is TNF; the disease is Myocardial fibrosis.