The cell surface receptors for interleukin-1α and interleukin-1β are identical

Interleukin-1 (IL-1) is a factor that can induce proliferation of murine T lymphocytes1,2 and can elicit a variety of other biological responses. These include bone resorption3, fibroblast proliferation4, acute phase protein release from hepatocytes5, cartilage breakdown6 and fever7. This spectrum of activities is consistent with a role for IL-1 as a mediator of inflammation. Recently, sequence data have shown that