A cytokine family of 9 genes making up a cytokine gene cluster at 2q14. These genes include IL1A, IL1B and IL1RN. In man interleukin 1 beta proprotein (biologically inactive) is released from activated macrophages and proteolytically processed by caspase 1 (CASP1/ICE) to its active form. This stimulates T-lymphocytes and antigen presenting cells. It also has effects on B-lymphocytes and haematopoeisis. If released into the blood it caused pyrexia.
It accordingly acts on
- Cell proliferation
- Cell differentiation
- Inflammatory pain sensitivity by induction of cyclooxygenase-2 (PTGS2/COX2) in the central nervous system (CNS)
Human interleukin 1 alpha is produced in much smaller quantities. Its precursor is biologically active. It can also be processed to a biologically active cell surface membrane form involved in growth control. A nuclear receptor for IL-1α also seems to exist as well as a receptor on nerve cells that is more sensitive to IL-1β.
There are several different receptors which are activated by both IL-1s:
- Type 1 receptor (CD121a) coded by IL1R1
- On T-cells
- Type 2 receptor (CD121b) coded by IL1R2