CARDIOVASCULAR ENGINEERING Journal for Extracorporeal Circulation, Assist Devices,Transplantation and Artificial Organs
	Volume 3, 1998, No 2

Clinical Relevance of Peripheral Monitoring of Direct and Indirect Antigen-Presentation Pathways after Heart Transplantation

N. M. van Besouw, L. M. B. Vaessen, W. Weimar

Abstract:
Background: Monitoring for the responses to alloantigens presented either by the direct or the indirect presentation pathway have been reported to be of clinical value after kidney transplantation. Amongst others the level of these responses may be dependent on the immunosuppressive treatment. Methods: We studied these pathways in peripheral blood mononuclear cells (PBMC) of cardiac transplant patients in an attempt to find a correlation between these tests and the clinical status of the patients. Results: Both before and after transplantation, comparable proportions of PBMC samples reacted in MLC (mixed lymphocyte cultures) to nondepleted donor spleen cells (direct route), but never to donor cells depleted for antigen-presenting cells (indirect route). In contrast, the latter route could easily be activated by a nominal antigen (tetanus toxoid (TET)) and persisted after transplantation. After transplantation the proportion of PBMC samples responding to TET was significantly suppressed, irrespective of the occurrence of rejection. Nevertheless, analyzing the level of PBMC reactivity, both the immune responses via the direct and indirect presentation route increased when cyclosporine A (CsA) levels inadvertently decreased to inadequate concentrations and acute rejection was diagnosed. During immunological quiescence high and low responders could be detected to both the direct and indirect pathway, while graft vascular disease (GVD) was only positively correlated with a higher PBMC reactivity to indirect presented TET antigens. Conclusion: The level of PBMC reactivity via both the direct and indirect presentation pathway is correlated with acute rejection early after transplantation, while only the indirect pathway was associated with GVD. These tests might be used as a tool for selecting patients in which tapering of immunosuppresion can safely be performed.

Keywords:
heart transplantation, antigen presentation pathways, immunosuppression, acute rejection, graft vascular disease

Address for Correspondence:

Reference:
(CVE. 1998; 3 (2): 105-111)

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