Causes of CD4 lymphopenia

• HIV infection: seroconversion illness and during disease progression • Acute viral infections* • Tuberculosis* • Sarcoidosis* • Corticosteroid therapy • Purine metabolism defects; ADA and PNP deficiency • SLE * Reduce CD4 counts when not associated with HIV and can further reduce levels in HIV infection. ADA, Adenosine deaminase; PNP, Putine nucleoside phosphorylase