Interleukin-1 (IL-1), originally known as Lymphocyte Activating Factor (LAF), activates T cell lymphocytes, which then proliferate and secrete interleukin-2 (IL-2). IL-1 is released primarily from stimulated macrophages and monocytes, but has also been shown to be released from several other types and is thought to play a key role in inflammatory and immune responses. Other synonyms for IL-1 include: endogenous pyrogen (EP), mitogenic protein (MP), Helper Peak-1 (HP-1), T Cell Replacing Factor III (TRF III or TRFM), B Cell Activating Factor (BAF) and B Cell Differentiation Factor (BDF) The two closely related agents Interleukin-1α (IL-1α) and Interleukin-1β (IL-1β) share 62% homology in amino acid sequence and elicit nearly identical biological responses. IL-1α and IL-1β are both approximately 17 kDa with some heterogeneity in the amount of glycosylation.

Interleukin-1 activates T cell lymphocytes, which then proliferate and secrete interleukin-2 (IL-2). IL-1 is released primarily from stimulated macrophages and monocytes, but has also been shown to be released from several other types and is thought to play a key role in inflammatory and immune responses.

Lyophilized from a 0.2 μm filtered buffered solution.

The biological activity is measured by the dose-dependent stimulation of MTS cleavage by murine D10S cells.