抗原或表面免疫球蛋白交键因子,例如抗-μ或金黄色葡萄球菌Cowan I(SAC)能激活B细胞。用抗-μ激活B细胞时,细胞的增殖需要B细胞生长因子(BCGF),细胞的分化需要B细胞分化因子(BCDF)。但是如用SAC激活人体休止期B细胞时,B细胞不需要外源性BCGF,只要与BCDF反应后就可以产生免疫球蛋白(Ig)。这提示SAC能起BCGF样作用或SAC能促使B细胞产生BCGF样的活性。已证明人恶性B细胞瘤系和/或EB病毒转化的B细胞能产生促B Antigen or surface immunoglobulin cross-linking factors, such as anti-μ or Staphylococcus aureus Cowan I (SAC), activate B cells. With anti-activated B cells, B cell growth factor (BCGF) is required for cell proliferation and B cell differentiation factor (BCDF) for cell differentiation. However, when activating human resting cell B cells with SAC, B cells do not require exogenous BCGF and immunoglobulins (Ig) can be produced as long as they react with BCDF. This suggests that SAC acts as a BCGF-like or SAC-stimulated B cell to produce BCGF-like activity. It has been demonstrated that human malignant B cell lines and / or EB virus transformed B cells produce pro-B