AIH Flashcards
disease of unknown cause that
is characterized by the presence of autoantibodies, hypergammaglobulinemia, and histologic features of interface hepatitis and lymphoplastic infiltration.
AIH
mainly affects females, regardless of age or ethnicity
mainly a disease of mid-to-late life and that its peak age of onset varies among countries.
The median age of onset in the Netherlands is 43 years in men and 48 years in women.
Histopathology of interface hepatitis.
The limiting plate of the portal tract is disrupted by a lymphoplasmacytic infiltrate. This histologic pattern is the hallmark of autoimmune hepatitis, but it is not disease specific.
Histopathology of lymphoplasmacytic infiltration.
Plasma cells denoted by perinuclear halos are present in the portal tract and extend into the liver parenchyma with the interface hepatitis
Pathophysiology
AIH is a consequence of perturbations in homeostatic mechanisms that maintain immune tolerance of self-antigens
Genetic Predosposition
The susceptibility alleles of AIH in white North Americans and northern Europeans are DRB103:01 and DRB104:01.55,56 DRB104:04 and DRB104:05 are the susceptibility alleles in Mexican, Japanese mainland Chinese, and Argentinian adults, and DRB104:05 and DQB104:01 are the susceptibility alleles in South Korea
The principal autoantigen of AIH
that is targeted by anti-LKM1 is cytochrome P450 2D6 (CYP2D6).
CLINICAL FEATURES
An acute severe (fulminant) presentation, defined by the onset of hepatic encephalopathy within 26 weeks of the discovery of the disease
predominant laboratory features for AIH
Serum AST, ALT, and γ-globulin elevations reflect the severity of liver inflammation
laboratory hallmark of the disease
increased serum immunoglobulin G (IgG)
an independent predictor of treatment
respons
serum GGTP level can be increased, and its improvement during
glucocorticoid therapy
Laboratory parameters
Hyperferritinemia is commonly present in conjunction with other disturbances in iron homeostasis, including a high serum iron concentration and increased transferrin saturation.
The conventional autoantibodies for the diagnosis of AIH
ANA, smooth muscle antibodies (SMA), and anti-LKM1
Autoantibodies
SMA, ANA, and anti-LKM1 can be detected by IIF using rodent tissues or Hep-2 cell lines or by enzyme immunoassay (ELISA) using adsorbed recombinant or highly purified anti- gens.
preferred method for diagnosing AIH
IIF has been the preferred method for diagnosing AIH because the recombinant antigens used in ELISAs may not be the same antigens detected by IIF.
Other serologic markers of AIH
atypical perinuclear anti-neutrophil cytoplasmic anti- bodies (pANCA), antibodies to soluble liver antigen (anti-SLA), antibodies to actin (anti-actin), and anti-LC1
Present in 80% of patients with type 1 AIH
Concurrent with SMA in 43% of patients with type 1 AIH Diagnostic accuracy is 56% as sole marker
ANA
Present in 63% of patients with type 1 AIH Diagnostic accuracy is 61% as sole marker Diagnostic accuracy is 74% if ANA present
SMA
Hallmark of type 2 AIH
ANA and SMA usually absent
Concurrent with anti-LC1 in 32% of patients with AIH Mainly present in children
Associated with HLA DRB1*07
Anti-LKM1
High diagnostic specificity for AIH (99%) Associated with HLA DRB1*0301
Commonly concurrent with anti-Ro/SSA (96%) Associated with severe disease and relapse May be sole marker of AIH
Anti-SLA
Present in 50%-92% of patients with type 1 AIH Absent in type 2 AIH
Associated with PSC and UC
May be the sole marker of AIH
May be the result of gut-derived reactivity
Atypical pANCA
Present in 86% of SMA-positive patients with AIH
Does not detect non–actin-associated SMA
Concurrence with anti–α-actinin is associated with severe disease
Anti-actin
Frequently concurrent with anti-LKM1 (32%)
Mainly present in young patients (age ≤ 20 yr) Associated with same clinical phenotype as anti-LKM1 Rare in North American patients
Anti-LC1
Histology
Interface hepatitis is required for the diagnosis of AIH
Lymphocytic or lymphoplasmacytic inflammation, hepatocyte rosetting, emperipolesis (penetration of one cell into and through a larger cell), and hepatocyte swelling are other common findings
The histologic features of acute severe (fulminant) AIH
centrilobular necrosis with hemorrhage, severe interface hepatitis, lymphoplasmacytic infiltration around the central vein with hepatocyte drop-out or necrosis (“centrilobular perivenuli- tis”), lymphoid aggregates (in 50%), and plasma cell infiltration (in 90%).
prognostic biomarkers
Serum
levels of ferritin, vitamin D, and angiotensin converting enzyme and circulating levels of miR-21 and miR-122, PD-1 and its ligands (PD- L1 and PD-L2), macrophage migration inhibitory factor, soluble CD163, and BAFF are being assessed as therapeutic biomarkers.
The definite diagnosis
requires the presence of ANA, SMA, or anti-LKM1 alone or in various combinations, hypergammaglobulinemia manifested mainly as an increased serum IgG level, histologic features of interface hepatitis, and exclusion of other similar diseases.
Transient elastography
Transient elastography does not become an accurate assessment of cirrhosis until glucocorticoid treatment has been administered for 6 months or longer.