Fatal lymphoma after transplantation of cultured thymus in children with combined immunodeficiency disease.

A fatal, widespread, polyclonal, B-cell immunoblastic lymphoproliferative disorder developed in three children with combined immunodeficiency shortly after intra-abdominal transplantation of cultured thymus epithelium for immunoreconstitution. All three had surface immunoglobulin-bearing cells (15 to 20 per cent) in the peripheral blood before transplantation and polyclonally elevated immunoglobulins afterward. Abnormal immunoregulation was demonstrated by a lack of concanavalin A-induced suppressor-cell activity in mixed leukocyte culture in all three patients before transplantation and in two afterward. We suggest that the transplant acted as a promoter through immunostimulation or production of promoter factors, and that excessive polyclonal B-cell proliferation resulted because of inadequate immunoregulatory mechanisms. Although this complication occurred in only three of 30 patients with various forms of immunodeficiency treated with cultured thymus, these cases illustrate a potential problem in immunoreconstitution of combined immunodeficiency disorders.