In addition, antibody blocking of 2B4, a co-stimulatory molecule on cytotoxic lymphocytes that uses SLAM-associated protein (SAP), and SAP is mutated in X-linked lymphoproliferative disease 1 (XLP1) thereby predisposing for EBV associated pathology, increases EBV viral loads and lymphomagenesis in humanized mice (73). The gene discussed is SH2D1A; the disease is X-linked lymphoproliferative syndrome.