Transplantation of allogeneic haemopoietic stem cells can cure several primary immunodeficiencies. This European report focuses on the long-term results of such procedures done between 1968 and December, 1999, for primary immunodeficiencies.

The report includes data from 37 centres in 18 countries, which participated in a European registry for stem-cell transplantation in severe combined immunodeficiencies (SCID) and in other immunodeficiency disorders (non-SCID). 1082 transplants in 919 patients were studied (566 in 475 SCID patients, 512 in 444 non-SCID patients; four procedures excluded owing to insufficient data). Minimum follow-up of 6 months was required.

In SCID, 3-year survival with sustained engraftment was significantly better after HLA-identical than after mismatched transplantation (77% vs 54%; p=0·002) and survival improved over time. In HLA-mismatched stem-cell transplantation, B(–) SCID had poorer prognosis than B(+) SCID. However, improvement with time occurred in both SCID phenotypes. In non-SCID, 3-year survival after genotypically HLA-matched, phenotypically HLA-matched, HLA-mismatched related, and unrelated-donor transplantation was 71%, 42%, 42%, and 59%, respectively (p=0·0006). Acute graft versus host disease predicted poor prognosis whatever the donor origin except in related HLA-identical transplantation in SCID.

The improvement in survival over time indicates more effective prevention and treatment of disease-related and procedure-related complications—eg, infections and graft versus host disease. An important factor is better prevention of graft versus host disease in the HLA-non-identical setting by use of more efficient methods of T-cell depletion. For non-SCID, stem-cell transplantation can provide a cure, and grafts from unrelated donors are almost as beneficial as those from genetically HLA-identical relatives.