Management of a novel immune deficiency with IL-2 therapy.

The present study describes a female child, who had a primary defect in the ability of her T-cells to secrete interleukin-2. Numbers of B- and T-cells were normal, but their functions were severely deficient. The patient had decreased immunoglobulins and poor ability to mount antibody responses. Phytohemagglutinin (PHA) and antigen-driven lymphoproliferative responses were diminished and were correctable in vitro with exogenous IL-2. Upon stimulation with PHA the patient's lymphocytes expressed IL-2 receptors normally, but were grossly deficient in endogenous IL-2 production. The patient was diagnosed as having a form of severe combined immunodeficiency disease at 6 months of age. Two attempts at immune reconstitution by haploidentical bone marrow transplantation failed to result in sustained engraftment. At age 18 months, treatment was initiated with rIL-2 10,000 units/kg i.v. daily and gradually increased to 30,000 units/kg. A marked improvement was noted, clinically as well as in T-cell immune functions. The child has been maintained on rIL-2 treatment at home for the past year without significant adverse effects, and she is currently receiving 30,000 units/kg of rIL-2 three times a week. This case illustrates that IL-2 is a potentially useful therapeutic modality which can be safely administered for prolonged periods to children with primary immunodeficiency diseases.