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J Autoimmun. 2010 Feb;34(1):7-14. doi: 10.1016/j.jaut.2009.08.010. Epub 2009 Sep 18.

Aetiopathogenesis of autoimmune hepatitis.

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1
Institute of Liver Studies, King's College London School of Medicine at King's College Hospital, Denmark Hill, London SE5 9RS, UK.

Abstract

Interface hepatitis, histological hallmark of autoimmune hepatitis (AIH), is a dense portal mononuclear cell infiltrate invading the parenchyma, consisting of CD4 and CD8 T-lymphocytes, monocytes/macrophages and plasma cells. What triggers AIH is unknown, but there is evidence that failure of immune homeostasis plays a permissive role allowing liver autoantigen-specific cells to attack hepatocytes. Damage is likely to be orchestrated by CD4 T-lymphocytes recognizing an autoantigenic liver peptide. For autoimmunity to arise, the peptide, embraced by an HLA class II molecule, must be presented to naïve CD4 T-helper (T(H)0) cells by professional antigen-presenting cells. Once activated, T(H)0 cells can differentiate into T(H)1 cells, which are pivotal to macrophage activation, enhance HLA class I expression, rendering liver cells vulnerable to CD8 T-cell attack, and induce HLA class II expression on hepatocytes; or into T(H)2 cells producing IL-4, IL-10 and IL-13, cytokines favouring autoantibody production by B-lymphocytes. Autoantigen recognition is tightly controlled by regulatory mechanisms, such as those exerted by CD4+CD25+ regulatory T-cells (T-regs). Numerical and functional T-reg impairment characterizes AIH, particularly during active disease. Advances in the study of autoreactive T-cells stem mostly from AIH type 2, where the main autoantigen, CYP2D6, is known enabling characterization of antigen-specific immune responses. Monocyte involvement in the autoimmune liver attack has been recently reported.

PMID:
19766456
DOI:
10.1016/j.jaut.2009.08.010
[Indexed for MEDLINE]
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