Elastase is a constituent product of T cells.

Proteases produced by immune cells have been found to be important components of the immune response to antigen. A protease previously unrecognized as a specific T cell product has been identified which has the gene sequence, serologic crossreactivity, and enzymatic specificity of elastase. T cell elastase, found in combination with the natural elastase inhibitor alpha 1-antitrypsin (alpha 1-protease inhibitor, alpha 1-PI), is produced by both CD4+ and CD8+ T lymphocytes, and is found both in a membrane-bound and in a soluble form in murine T cell lines.