Expression of CD80 and CD86 on B cells during coxsackievirus B3-induced acute myocarditis

Introduction
The pathogenesis of viral myocarditis (VMC) is unclear, but many studies have shown that VMC is associated with an excessive immune response. CD80 and CD86 are important costimulatory molecules that play a critical role in autoimmunity. However, whether CD80+/CD86+ B cells participate in the pathogenesis of acute VMC is unknown.

Material and methods
Male C57BL/6 mice were infected by intraperitoneal injection with coxsackievirus B3 (CVB3) to establish a VMC model. Control mice were administered phosphate-buffered saline intraperitoneally. At one week and two weeks post injection, histopathological changes in heart tissue were assessed with haematoxylin and eosin staining. The frequency of splenic CD80+/CD86+ B cells was measured with flow cytometry.

Results
The frequency of CD80+ B cells was significantly increased in VMC, while the frequency of CD86+ B cells was significantly decreased. Furthermore, the frequency of CD80+ B cells related to the severity of VMC.

Conclusions
These data show that CD80+/CD86+B cells are involved in the pathogenesis of VMC, with CD80+B cells being more important than CD86+B cells.