A mitogen is any of many substances that cause cells (especially white blood cells) to divide (undergo mitosis). Mitogens can often trigger immune system responses by stimulating lymphocyte activity; others improve the growth of tissues or cell cultures. Thus, mitogens are invaluable to biomedical researchers who are studying cells and cell cycles.
Some medical references will use "mitogen" interchangeably with "cell growth factor"; others will use it only in reference to substances that stimulate immune cells. Mitogens are always polypeptides that can be composed of as many as 100 amino acids. They work by attaching to specific protein receptors on the surface of cells that then cause the cells to start dividing.
A few important immune system