Intra-graft proliferation of naive and memory T lymphocytes during hepatic allograft rejection

52

Gene&

REDOX-SENSITIVE TRANSCRIPTION FACTORS NF-xB AND AP-1 ARE INVOLVED IN THE HEPATIC PROTECTION FROM ISCHEMIA-REPERFUSION INJURY (IRPI) BY THE ATRIAL NATRIURETIC

PEPTIDE

IANP)

A.K. Kiemer” ._7 M. Bilzer? AM. Vollmar’, and A.L. Gerbes’ ‘Institute of Pharmacology, Toxicology and Pharmacy, Koniginstr. 16, and ‘Department of MedicineII, Klinikum GroDhaderniLudwig-MaximihansUniversity, Munich, Germany Background: Ischemia-reperfusioninjury (IRPI) is a major clinical problem after liver transplantation. We have shown that ANP prevents IRPI of the rat liver after 24 h storage in cold UW solution. ANP seems to interfere with oxidative stress during IRPI, the mechanisms remain to be detined. Therefore, aim of this study was to investigate potential mechanisms of ANP protection, particularly effects on redox-sensitive transcription factors. Methods: Livers of male Sprague-Dawley rats were perfused in a nonrecirculating fashion with or without ANP (200 nM, n=4 each)for 20 min preceeding24 h storage in UW solution. Adenosine nucleotide concentration, activation of NP-KB and AP-1 (EMSA), as well as mRNA coding for iNOS, COX-2 andTNP-a mRNA (Northern Blot) were determinedin heeze clamped liver samples during 2 h of reperfusion. Results: ANP prevented IRPI as shown by significant improvement of bile flow, reduction of sinusoidal release of LDH andPNP and histological analysis. ANP had no effect on portal pressure increase as indicator of impaired hepatic circulation, nor on energy depletion determined by adenosine nucleotide decrease. During reperfusion NF-KB (at 45 min) and AP-1 (120 min) binding activities were severalfold augmented accompanied by increased TNP-a mRNA expression. ANP pretreatment clearly reduced these effects. Since neither iNOS nor COX-2 mRNA could be detectedduring 2 h mperfusion, an involvement of these two inflammatory enzymes in our model of IRPI is unlikely. Conclusions: Hepaticprotection from coldIRP1 by ANP is not linked to vasodilation nor to an influence on intracellular energy status. Suppression of NF-KB and AP-1 activation by ANP seems to be involved.

INTRA-GRAFT

PROLIFJlRATION

LYMPHOCYTES

DURING HEPATIC ALLOGRAFT

OF

NAIVE

MM Dollinaer’~*. SEM Howie’, JN Plev&.

AND

sessions

MEMORY

T

REJECTION

PC Haves* DJ

I-hTiSOll’.

Department of Pathology’ and Department of Medicine’, University of Edinburgh, Edinburgh EH8 9AG, Scotland, UK. Liver allograft rejection is mediated by a primary response of T lymphocytes followed by infiltration of the graft with a mixed inflammatory reaction. We have demonstrated intra-hepatic proliferation of lymphocytes during acute/chronic liver allograft rejection. Aim: To charactcrise proliferating lymphocytes in the grail tissue during acute/chronic rejection (AR/CR). Method: Paraffin-embedded liver biopsies of 10 patients with AR before/after treatment with i.v. steroids, 10 patients with CR and 10 patients without rejection post-transplant were studied by immunocytochemistry using double-labelling. Results: During acute and chronic rejection, naive CD4+ CD45RA+ and memory CD4+ CD45RO+ T lymphocytes were predominantly located inside tire portal tracts, while CD8+ T lymphocytes, CD57+ natural killer cells and CD68+ macrophages were distributed intraparenchymally. As previously, K&67+ cells showed a periportal distribution. These were predominantly CD4+ CD45RA+ and CD4+ CD45RO+, that is both naive and memory T lymphocytes. Conclusion: Our findings demonstrate for the first time proliferation of naive T lymphocytes representing a primary immune response within the allogratt. This implicates not only intrahepatic proliferation of T lymphocytes as a prominent feature of rejection, but also suggests that the liver has a special immunological status comparable to lymphatic tissue.