Interleukin-7 treatment of PML in a patient with idiopathic lymphocytopenia

Objective: To describe the compassionate use of interleukin-7 (IL-7) for treatment of progressive multifocal leukoencephalopathy (PML) in the setting of idiopathic CD81 greater than CD4+ lymphocytopenia. Methods: A 66-year-old HIV-seronegative man presented with progressive language dysfunction. MRI showed hyperintense lesions in the left hemispheric white matter withmild contrast enhancement. A brain biopsy performed 4 months after symptom onset established the diagnosis of PML. The patient had profound lymphocytopenia with absolute lymphocyte count (ALC) at 168 cells/ μL, 87 CD4+ T cells/μL, and 7 CD8+ T cells/μL. There was no evidence of hematologic malignancy or rheumatologic disease. Results: The patient received 3 intramuscular injections of IL-7 at a dose of 10 μg/kg per week with no adverse effects. ALC peaked at 595 cells/μL, CD41 T cells at 301 cells/μL, and CD8+ T cells at 34 cells/μL 3 weeks after completion of treatment. His lesions on MRI stabilized and neurologic examination mildly improved. JCV-specific T-cell responses measured by intracellular cytokine staining were not altered after treatment with IL-7 but there was a marked increase in regulatory T cells. Conclusion: This case further supports the investigational use of IL-7 in patients who develop PML in the setting of ICL.