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J. Exp. Med.,
Volume 189, Number 2, January 18, 1999 441-446
By


From the * Liver Research Laboratories, The University of Birmingham, Institute of Clinical Science,
Queen Elizabeth Hospital, Birmingham B15 2TH, United Kingdom; the We propose that a novel mechanism of hepatocyte apoptosis, involving a cooperative interaction between CD40 and Fas, is involved in the hepatocyte loss of chronic liver allograft rejection. We detected increased hepatocyte expression of Fas, Fas ligand (FasL), and CD40 associated with dropout of centrilobular (acinar zone 3) hepatocytes in chronic allograft rejection.
Expression of CD40 ligand (CD40L) was also increased but was largely restricted to CD68+
macrophages. A functional role for CD40 and Fas in hepatocyte apoptosis was demonstrated in
vitro using primary human hepatocytes and the HepG2 cell line in both of which apoptosis was
induced, not only by cross-linking Fas directly but also via CD40 activation. Our data suggest
that CD40 activation induces apoptosis via Fas because (a) ligation of CD40 upregulated hepatocyte FasL expression, and (b) apoptosis induced via activation of CD40 was prevented by a
neutralizing monoclonal antibody to FasL. Thus, CD40 engagement triggers apoptosis of human hepatocytes and might amplify Fas-dependent hepatocyte apoptosis in chronic rejection
and other inflammatory liver diseases in which Fas-mediated apoptosis is involved.
CRC Institute for
Cancer Studies, The University of Birmingham Medical School, Edgbaston, Birmingham B15 2TJ,
United Kingdom; and the § Department of Pathology, University of Birmingham, Edgbaston,
Birmingham B15 2TT, United Kingdom
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