Patients with X-Linked Lymphoproliferative Syndrome Type 1 (XLP1) Have Mutations $\gamma$

Patients with X-linked lymphoproliferative syndrome type 1 (XLP1) have mutations in the SLAM-family adapter protein, SAP. These patients suffer from an inability to control infections of the herpesvirus Epstein-Barr virus (EBV) that infects B cells. Studies have been done using peripheral blood T cells from these patients to examine their response to EBV in comparison to the responses of normal individuals (EBV-infected) as controls. These data were obtained by ELISPOT analysis, to quantify the numbers of IFN- $\gamma$ -producing CD8 T cells per million peripheral blood leukocytes in response to several EBV peptides, indicated as peptide 1, 2, 3, or 4 (note: the patients and controls were matched for HLA class I molecules) .

These results indicate that:

A) XLP patients have a defect in priming CD8 T cell responses following EBV infection.
B) XLP patients require IFN- $\gamma$ production to kill EBV-infected B cells.
C) XLP patients have normal CD8 effector cell priming following EBV infection.
D) XLP patients have a defect in cytotoxicity by NK cells rather than by CD8 T cells.
E) XLP patients have no defect in cytotoxicity by CD8 T cells.