Interleukin-7 (CYT107) Treatment of Idiopathic CD4 Lymphocytopenia: Expansion of CD4 T Cells (ICICLE) is a Phase I/IIa open-label, single arm clinical trial evaluating the safety profile of glycosylated recombinant human interleukin-7 (rhIL-7) as an immunostimulatory therapy in patients with idiopathic CD4 T cell lymphocytopenia (ICL) at risk of disease progression. Secondary analyses will assess the immunostimulatory effects of rhIL-7 on T cell number and function.