¹Fetal Treatment Center at the University of California, San Francisco, USA

²Department of Immunology at Genentech, Inc., South San Francisco, USA

³SyStemix Inc., Palo Alto, CA, USA

⁴Department of Immunogenetics and Transplantation at the University of California, San Francisco, USA

Correspondence to: Dr M O Muench, University of California at San Francisco; 3rd & Parnassus Avenue, Room U-442, San Francisco, CA 94143-0793, USA

A fetus diagnosed with X-linked chronic granulomatous disease was transplanted with Thy-1⁺CD34⁺ cells of paternal origin. The transplant was performed at 14 weeks gestation by ultrasound guided injection into the peritoneal cavity. The fetus was delivered at 38 weeks gestation after an otherwise uneventful pregnancy. Umbilical cord blood was collected and used to determine the level of peripheral blood chimerism as well as levels of functional engrafted cells. Flow cytometry was used to detect donor leukocytes identified as HLA-A2^-B7⁺ cells, whereas recipient cells were identified as HLA-A2⁺B7^- cells. No evidence of donor cell engraftment above a level of 0.01% was found. PCR was used to detect HLA-DRB1*15⁺ donor cells among the recipient's HLA-DRB1*15^- cells, but no engraftment was seen with a sensitivity of 1:1000. The presence of functional, donor-derived neutrophils was assessed by flow cytometry using two different fluorescent dyes that measure reactive oxygen species generated by the phagocyte NADPH oxidase. No evidence of paternal-derived functional neutrophils above a level of 0.15% was observed. Peripheral blood and bone marrow samples were collected at 6 months of age. Neither sample showed engraftment by HLA typing using both flow cytometry and PCR. Functional phagocytes were also not observed. Furthermore, no indication of immunological tolerance specific for the donor cells was indicated by a mixed lymphocyte reaction assay performed at 6 months of age. While there appears to be no engraftment of the donor stem cells, the transplant caused no harm to the fetus and the child was healthy at 6 months of age. Analyses of fetal tissues, obtained from elective abortions, revealed that CD3⁺ T cells and CD56⁺CD3^- NK cells are present in the liver at 8 weeks gestation and in the blood by 9 weeks gestation. The presence of these lymphocytes may contribute to the lack of donor cell engraftment in the human fetus. Bone Marrow Transplantation (2001) 27, 355-364.

in utero transplantation; chronic granulomatous disease; hematopoietic stem cells; Thy-1⁺CD34⁺ cells; fetal therapy