TIA-1, T-cell intracellular antigen-1, granule membrane protein 17

TIA-1 is a 15 kD cytotoxic granule-associated protein. expressed by cytotoxic T-cells1. Perforin punctures a hole in the membrane of a target cell. TIA-1 and granzyme enter through the hole and activate proteins which induce apoptosis2. Perforin and granzyme are only expressed upon activation of cytotoxic cells; TIA-1 is expressed irrespective of the activation state of cytotoxic T-cells and myeloid cells2. This is in contrast to perforin and granzyme B, the expression of which increases in activated cells.

Immunohistochemical expression

It is expressed by:

Diagnostic utility


1 Hatano, B., K. Ohshima, et al. (2002). "Non-HTLV-1-associated primary gastric T-cell lymphomas show cytotoxic activity: clinicopathological, immunohistochemical characteristics and TIA-1 expression in 31 cases." Histopathology 41(5): 421-36.

2 Mori, N., Y. I. Murakami, et al. (2004). "TIA-1 expression in hairy cell leukemia." Mod Pathol 17(7): 840-6.

This page last revised 1.9.2004.

©SMUHT/PW Bishop