Interleukin-2–inducible T-cell kinase (ITK)

Interleukin-2–inducible T-cell kinase (ITK) is a 71–72 kDa non-receptor tyrosine kinase of the Tec family, predominantly expressed in T lymphocytes and to a lesser extent in natural killer cells and mast cells[1][2][5][7]. ITK features multiple regulatory domains—including PH, TH, SH2, SH3, and a kinase domain—and plays a central role in transmitting signals from the T cell receptor (TCR) to downstream effectors. Upon TCR engagement, ITK is recruited to the membrane, becomes activated via phosphorylation, and then phosphorylates phospholipase C gamma 1 (PLCγ1), leading to calcium mobilization and activation of multiple transcriptional pathways essential for T cell activation, proliferation, and differentiation[1][2][5][7]. ITK is critical for the development and function of multiple T cell subsets, particularly Th2 and Th17 cells, and has been implicated in diseases including lymphoma, leukemia, immune deficiencies, and inflammatory conditions[1][2][5][7]. Pharmacological inhibition of ITK, by agents such as ibrutinib or CPI-818, is under investigation for cancer and immunomodulatory therapy but faces challenges with immune suppression and kinase selectivity[1][3][4][6][7].

Other names

Tyrosine-protein kinase ITK/TSKEmtTskInterleukin-2–inducible kinase

Inhibition of ITK kinase activity, leading to suppression of T cell receptor (TCR) downstream signaling Blocking phosphorylation of PLCγ1, thereby reducing calcium mobilization and downstream activation of NFAT, MAPK, PKC, and NF-κB pathways Selective dampening of Th2-type cytokine responses and modulation of T cell–mediated immunity