Phytohemagglutinin (PHA)

Phytohemagglutinin (PHA) is a glycoprotein from red kidney beans (Phaseolus vulgaris) that acts as a potent mitogen, stimulating lymphocyte proliferation and transforming them into large blast cells. It can suppress humoral antibody responses and enhance the survival of homografts by inhibiting immune rejection. It also triggers T-cell activation and apoptosis by upregulating pro-apoptotic proteins like Bax, leading to the activation of caspase-3.