Granulysin

Where it comes from

Made in

Cytotoxic T cells and natural killer cells, stored in their granules with perforin and granzymes

Sent out by

When the killer cell meets an infected or malignant target

Acts on

• Bacteria (including tuberculosis), fungi and parasites inside cells
• Tumour cells
• Keratinocytes in drug reactions

What it does

• Kills intracellular microbes, including tuberculosis bacteria, once perforin lets it into the cell ³
• Kills the target cell too, by damaging its mitochondria
• The 15-kDa form is a signal that activates monocytes rather than a toxin ²

In medicine

• The main executioner in Stevens-Johnson syndrome and toxic epidermal necrolysis: blister fluid is full of it, and blood granulysin is a research marker ¹
• Nothing is treated through it; what is studied is whether the measurement can tell those reactions from a harmless drug rash early enough to matter ¹

Beyond the body’s own use

• Engineered fragments are tested as antibiotics and as anticancer agents in the laboratory; none is in a trial
• Mice have no granulysin gene, so every question about it has to be asked in human cells or in mice given the human one; that is the main reason it is less developed than perforin or the granzymes ²