As seen in other syndromes susceptible to EBV-LPD (e.g. patients with SAP, XIAP, CD27 and Coronin-1A deficiency) NKT cells are severely reduced in the peripheral blood of ITK deficient patients [18]; hence a critical role has been postulated for NKT cells in the response to EBV infection [19]. Here, ITK is linked to Epstein-Barr virus infection.