Cytolytic cytokine that is produced in the cytolytic granules of activated cytotoxic T cells (CD8) and NK cells. It is active together with the cytokine perforin. Perforin is integrated into the cell membrane of the target cell, where it forms a pore-like structure. Certain serine proteases (e.g. granzymes) penetrate the target cell through this pore and trigger apoptosis. Granulysin has a broad antimicrobial effect. It leads to the destruction of keratinocytes in certain inflammatory processes of the skin, such as Stevens-Johnson syndrome or toxic epidermal necrolysis. The concentration of granulysin in the blister contents is directly correlated with the severity of the disease. Large quantities of granulysin can also be detected in the blisters of erythema multiforme.