Description
Human CD4+ helper T cells express the CD4 co-receptor and play an important role in the adaptive immune system by assisting other white blood cells. These cells are activated when they are presented an antigen on the MHC class II molecule of an antigen-presenting cell (APC). Once activated, CD4+ helper T cells secrete lymphokines that assist in the activation of B cells to secrete antibodies that target specific microbes and assist in the activation of cytotoxic T cells to destroy infected target cells.


