Systemic lupus erythematosus, progressive multifocal leukoencephalopathy, and T-CD4+ lymphopenia.

Progressive multifocal leukoencephalopathy (PML) is a rare opportunistic infection caused by the reactivation of JC virus and occurs in patients with severe primary or secondary immunosuppression. Recently, PML is becoming relevant in autoimmune disorders, particularly in patients treated with biologic agents. However, systemic lupus erythematosus (SLE) appears to be associated with susceptibility to PML that cannot be entirely explained by the immunosuppressive therapy. The authors present two patients with the diagnosis of SLE and PML: One had a heavy immunosuppressive therapy history, and the other had never experienced biologic or cytotoxic therapeutics. Both patients had a profound T-CD4+ lymphopenia during their clinical history. These two cases emphasize the importance of CD4+ lymphopenia in SLE patients with and without immunosuppressors regarding opportunistic infections.