singlecenter analysis of longterm outcome after hematopoietic cell transplantation in children with congenital severe t cell immunodeficiency we review clinical outcome and immune reconstitution in a consecutive series of 74 infants with severe t cell immunodeficiency who received hematopoietic cell transplantation hct from january 1991 to may 2003 fiftythree patients 716 are alive results were significantly better for recipients of hct from hlamatched related donors 100 survival and unrelated donors 864 than from mismatched related donors 516 a detailed analysis of immune reconstitution and clinical status was performed in 49 surviving patients most of which have attained robust t and b cell reconstitution and are in very good clinical conditions no cases of late deaths or of chronic graftversushost disease gvhd have been observed however infections and autoimmunity at 1 year after hct have been observed in a significant number of patients persistence of a low number of circulating naive t cells and longterm requirement for intravenous immunoglobulin were associated with a higher incidence of clinical events