Treatment of idiopathic CD4 T lymphocytopenia with IL-2

Idiopathic CD4 T lymphocytopenia (ICL) is an unusual immune defect in which there is an unexplained deficit of CD4 T cells, leading to fungal, parasit ic or other serious opportunistic infections. Current treatment efforts are directed at eliminating infections. Here we describe the use of a novel tr eatment, subcutaneous polyethylene glycol (PEG)-IL-2 injections, in a woman with this disorder, who had chronic severe mycobacterial disease which led to repeated hospitalizations, and advancing respiratory insufficiency. For this patient, PEG-IL-2, 50 000 U/m(2), has been given by weekly subcutaneo us injections for 5.5 years. This treatment has resulted in marked (and sti ll continuing) long-term immunological improvement with normalized T cell f unctions and increased CD4 cell numbers. She has had substantial clinical i mprovement with clearing of mycobacterial disease, reducing hospitalization s and improved lung functions. The improvement seen in this patient suggest s that low-dose IL-2 is a safe and practical therapy, which might be useful in other subjects with this potentially serious immune defect.