Pneumocystis jirovecii pneumonia in two patients with systemic lupus erythematosus after rituximab therapy.

New cases of Pneumocystis jirovecii pneumonia (PJP) have recently been reported in patients with systemic lupus erythematosus (SLE) after rituximab therapy. Several factors may contribute to susceptibility to P. jirovecii infection in this type of patients, including the immunological characteristics of the disease, the mechanisms of rituximab action, environmental factors, and the biological characteristics of the fungus. We report two patients with SLE who developed PJP after rituximab therapy.