The development of anti–PD-1 CAR–mediated or -accelerated immunodeficiency characterized by loss of memory CD4+ and CD8+ T cells, increased SIV replication, and development of an abnormal nodular lymphoma-like condition associated with LCV RNA+ cells was likely mediated by one or several mechanisms that hampered the antiviral responses of the T and B cell compartment. The gene discussed is CD4; the disease is immune system disorder.