To the Editor.
—We are concerned by the recent report of a clinical trial of embryonic brain tissue transplantation without immunosuppression in a human patient with Parkinson's disease.1 The authors of this report cited several previous studies that have shown that substantia nigra allografts survive in animals without immunosuppression, and on that basis immunosuppression was not used.It is true that several studies, by our group and others,2-6 have shown that allografts of embryonic brain tissue often survive transplantation into the brains of animals without the use of any immunosuppressive measures. It has recently become apparent, however, that this is not an immutable property of brain as a site for transplantation, but instead depends on the particular strain combinations that are used. Some studies have, in fact, reported poor survival of brain tissue allografts. Studies by Nicholas and Arnason3,7 and by Mason and coworkers8 have shown
Freed WJ, Poltorak M. Comments on Brain Tissue Transplantation Without Immunosuppression. Arch Neurol. 1991;48(3):259–260. doi:10.1001/archneur.1991.00530150027010
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