Markert, M. L.Marques, J. G.Neven, B.Devlin, B. H.McCarthy, E. A.Chinn, I. K.Albuquerque, A. S.Silva, S. L.Pignata, C.de Saint Basile, G.Victorino, R. M.Picard, C.Debre, M.Mahlaoui, N.Fischer, A.Sousa, A. E.2014-08-262014-08-262010Blood, 13 January 2011, Volume 117, Number 20006-4971http://dx.doi.org/10.1182/blood-2010-06-292490http://hdl.handle.net/10451/11736Conflict-of-interest disclosure: M.L.M. receives funding from the NIH and the FDA and has a patent pending for culture conditions for thymus tissue for transplantation. B.H.D. and I.K.C. receive funding from the NIH, and E.A.M. receives funding from the NIH and the FDA. The remaining authors declare no competing financial interests.© 2011 by The American Society of HematologyFOXN1 deficiency is a primary immunodeficiency characterized by athymia, alopecia totalis, and nail dystrophy. Two infants with FOXN1 deficiency were transplanted with cultured postnatal thymus tissue. Subject 1 presented with disseminated Bacillus Calmette-Guérin infection and oligoclonal T cells with no naive markers. Subject 2 had respiratory failure, human herpes virus 6 infection, cytopenias, and no circulating T cells. The subjects were given thymus transplants at 14 and 9 months of life, respectively. Subject 1 received immunosuppression before and for 10 months after transplantation. With follow up of 4.9 and 2.9 years, subjects 1 and 2 are well without infectious complications. The pretransplantation mycobacterial disease in subject 1 and cytopenias in subject 2 resolved. Subject 2 developed autoimmune thyroid disease 1.6 years after transplantation. Both subjects developed functional immunity. Subjects 1 and 2 have 1053/mm(3) and 1232/mm(3) CD3(+) cells, 647/mm(3) and 868/mm(3) CD4(+) T cells, 213/mm(3) and 425/mm(3) naive CD4(+) T cells, and 10 200 and 5700 T-cell receptor rearrangement excision circles per 100 000 CD3(+) cells, respectively. They have normal CD4 T-cell receptor β variable repertoires. Both subjects developed antigen-specific proliferative responses and have discontinued immunoglobulin replacement. In summary, thymus transplantation led to T-cell reconstitution and function in these FOXN1 deficient infants.engjournal article