Elevation of serum IgE level and peripheral eosinophil count during T lymphocyte-directed gene therapy for ADA deficiency: implication of Tc2-like cells after gene transduction procedure

We have successfully carried out T-cell-directed gene therapy for a boy wit h severe combined immunodeficiency due to adenosine deaminase deficiency (A DA(-) SCID) and unexpectedly found an elevation of serum IgE level and peri pheral eosinophil count during the course. More than 90% of transduced cell s cultured for 7-11 days before infusion into the patient were positive for CD8 and expressed Th2-type cytokine genes such as IL-4, IL-5 and IL-13. Fu rthermore, CD4(+) T-depleted PBMC (peripheral blood mononuclear cells) from the patient synthesized IgE in vitro by stimulation with IL-4. Collectivel y, these results suggested that Tc2-like cells in the transduced cells have distinct immunological functions to help IgE synthesis and activate eosino phils. (C) 1998 Elsevier Science B.V. All rights reserved.