[3][7] In boys with X-linked lymphoproliferative disorder, the inability to mount an immune response to EBV may lead to death via hemophagocytic lymphohistiocytosis (HLH).

Other observed symptoms of XLP include aplastic anemia, vasculitis, chronic gastritis, and skin lesions, as well as IM.

[3][8] Nearly half of XLP patients express humoral immune anomalies, which can include diminished responses to vaccines and low levels of immunoglobulin G (IgG).

Typically, after the receptors bind to their associated ligands, the immunoreceptor tyrosine-based switch motifs (ITSMs) in their cytoplasms are phosphorylated, which activates cell-activating signaling pathways.

Ligand binding thus fails to activate natural killer (NK) and cytotoxic T cells that typically eliminate EBV infection, leading to cytokine overproduction and tissue damage.

[13] XIAP-deficient individuals also produce low numbers of natural killer cells, a feature shared with XLP1 patients, which leads to a similarly inefficient response to EBV infection.

Care differs depending on the phenotype of XLP expressed, with treatments varying between those experiencing HLH or lymphoma, and whether or not they have been infected with EBV.