Although not yet clinically approved, CYT107 — a glycosylated, long-acting, recombinant human IL-7 — has been used in over 650 adult and pediatric patients with severe lymphopenia due to various etiologies including sepsis, AIDS, radiation and chemotherapy, bone marrow reconstitution following stem cell transplantation, and refractory viral and fungal infections (29–32). Here, IL7 is linked to lymphopenia.