Mitogen

See also: Growth Factor

A mitogen is a chemical substance that encourages a cell to commence cell division, triggering mitosis. A mitogen is usually some form of a protein.

Mitogenesis is the induction (triggering) of mitosis, typically via a mitogen.

Mitogens trigger signal transduction pathways in which mitogen-activated protein kinase is involved, leading to mitosis.

Use in immunology

B cells can enter mitosis when they encounter an antigen matching their immunoglobulin.

Mitogens are often used to stimulate lymphocytes and therefore assess immune function.

The most commonly used mitogens in clinical laboratory medicine are:

Name	Acts upon T cells?	Acts upon B cells?
phytohaemagglutinin (PHA)	yes	no
concanavalin A (conA)	yes	no
lipopolysaccharide (LPS)	no	yes
pokeweed mitogen (PWM)	yes	yes

Lipopolysaccharide toxin from gram-negative bacteria is thymus-independent. They may directly activate B cells, regardless of their antigenic specificity.

Plasma cells are terminally differentiated and, therefore, cannot undergo mitosis. Memory B cells can proliferate to produce more memory cells or plasma B cells. This is how the mitogen works, that is, by inducing mitosis in memory B cells to cause them to divide, with some becoming plasma cells.

Mitogens in human physiology

Insulin-like Growth Factor 1 mediates the major growth-promoting effect of Human Growth Hormone as a paracrine agent at growth plates in the skeletal system.

Other uses

Mitogens also induce the activity of the PTGS2 enzyme.

External links

• MeSH Mitogens
• Mitogen at eMedicine Dictionary