Antimicrobial protein that kills intracellular pathogens. Active against a broad range of microbes, including Gram-positive and Gram-negative bacteria, fungi, and parasites. Kills Mycobacterium tuberculosis. Located in the cytotoxic granules of T-cells, which are released upon antigen stimulation. Expressed in natural killer and T-cells. By T-cell growth factor and IL2/interleukin-2. A 9 kDa form is produced by proteolytic processing of a 15 kDa protein.