Progressive multifocal leukoencephalopathy in a patient with common variable immunodeficiency and abnormal CD8+ T-cell subset distribution

JC virus infection should be considered in the differential diagnosis of the patient with CVID and signs and symptoms of encephalopathy. The role of this patient's abnormal CD8+ T-cell subset distribution in the development or control of this rare infection is worthy of consideration and has encouraged us to enumerate naive and memory CD4+ and CD8+ T-cell subsets in patients diagnosed as having CVID, even in the absence of neurodegenerative symptoms.