Saving the red baby: successful allogeneic cord blood transplantation in Omenn syndrome.

[omenn syndrome]

Haematopoietic stem cell transplantation is the treatment of choice for severe primary immunodeficiencies , but only has moderate prognosis in Omenn syndrome as it is complicated by highly activated Omenn T -cells resulting in delayed T -cell engraftment and a high rate of graft failure . A 6 1 /2 months old patient with a previously unknown compound heterozygous defect within the RAG 1 gene (R 474 C ; R 975 W ) underwent 8 /10 HLA-matched cord blood transplantation after myeloablative conditioning . Immune reconstitution was impressive with T -, B- and NK-cells reaching the median of age-dependent reference values within twelve , four and two months respectively . With a continuous decrease of activated Omenn T -cells there was a steady increase of naive , probably thymus-derived T -cells . Polyclonal B-cell activation and hypergammaglobulinaemia disappeared with B-cell engraftment . This case emphasizes that , despite their naive status and HLA-barriers , cord blood T -cells were apparently able to achieve T -effector function resulting in the elimination of all activated Omenn T -cells .