Abstract
This chapter focuses on the current state of knowledge of the structure and function of perforin. The properties of other granule proteins, granzymes and proteoglycan, are reviewed in this chapter. Perforin is localized in the cytoplasmic granules of cytolytic T cells and NK cells, where it is associated with the granule proteoglycan chondroitin sulfate A. Because they contain perforin, isolated cytoplasmic granules are highly cytolytically active in the presence of Ca. Perforin has recently been isolated and characterized, including sequence determination by complementary (cDNA) cloning. The tools generated by this work are being used for a critical assessment of the role of perforin as opposed to other molecules in lymphocyte-mediated cytolysis. Lymphocyte-mediated cytotoxicity by perforin has three effects. The direct membrane damage by transmembrane channel formation can lead to target cell lysis by the effects of osmotic imbalance and the loss of the transmembrane potential.