CD40L is transiently expressed on antigen-activated CD4~+ T cells in the form of trimer. It can also be normally expressed on germinal center (GC) B cells or abnormally expressed on B cell-originated malignant cells.

• CD40L主要以三聚体的形式瞬时表达在抗原活化的CD4~+T细胞表面,也可以瞬时表达在生发中心的B细胞和异位表达在一些B细胞系来源的肿瘤细胞上。