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J Thorac Cardiovasc Surg 1995;110:1773-1774
© 1995 Mosby, Inc.

LETTERS TO THE EDITOR

Modulation of alloreactivity in transplant recipients by phenotypic manipulation of donor endothelium

Section of Cardiothoracic Surgery
Guthrie Clinic Ltd.
Guthrie Square
Sayre, PA 18840

Reply to the Editor:

My colleagues and I appreciate the comments by Dr. Sundt regarding our article "Modulation of Alloreactivity in Transplant Recipients by Phenotypic Manipulation of Donor Endothelium." We must emphasize that these data represent a "pilot" project only and that the mechanism of the observed phenomenon is yet to be established. As outlined, our conclusions are hypotheses presently under investigation.

When the study was initially designed, we realized that the most definitive trafficking study would include transfection of the host endothelial cells with a vector that is replication defective and that contains ß-galactosidase and neomycin-resistant genes. Incubation of transplant sections with X-gal chromagen would demonstrate blue chromatin if transfected cells were present. At the time, our laboratory did not have such technology (Nabel et al. Science 1990;244:1342-4). In this pilot project, we substituted the fluorescent cell label for this sophisticated technique. Although this latter method is somewhat primitive, we were satisfied that with simple fluorescent light microscopy, these labeled cells remained in the vessel wall, because we could easily differentiate blood vessels from the myocardial parenchyma. One would have expected this "tag" to be located in the extravascular space (in association with macrophages) if the labeled cells were not viable. We could not demonstrate any PKH 26 dye (Zynaxis Cell Sciences, Inc., Malvern, Pa.) outside the vascular tree, even 15 days after graft perfusion.

We agree that a double-staining immunofluorescence technique to demonstrate phenotypic modification would support our hypothesis; however, our initial attempts at this were technically unsuccessful. In fact, we used OX 3 (Lewis) and MCA 13 (Brown Norway), monoclonal antibodies (Harlan Bioproducts, Indianapolis, Ind.) labeled with fluoroscein and rhodopsin, respectively, but we were unable to reproducibly stain even our control sections.

We used mixed lymphocyte culture and skin grafting as our method to determine tolerance. Both of these are old, unchallenged, standard models in transplantation biology. One must interpret the results of such experiments with caution, particularly in the context of both sensitization and chemical immunosuppression, as was the case in this study. We agree that retransplantation of these hearts into naive recipients would offer some insight into the mechanism of this phenomenon (ie., pan suppression vs. local suppression).

In conclusion, we remain excited about the results of this very simple model involving manipulation of an allograft to promote long-term survival. We hope that this initial report will stimulate other laboratories to refocus their research at the donor organ rather than the recipient.

12/8/68741

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Robert L. Quigley Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Quigley, R. L. Search for Related Content PubMed Articles by Quigley, R. L.