Diagnostic relevance and clinical significance of the new enhanced performance M2 (MIT3) ELISA for the detection of IgA and IgG antimitochondrial antibodies in primary biliary cirrhosis

Bone marrow findings in patients with autoimmune liver diseases

BACKGROUND AND AIMS

We have recently reported quantitative and qualitative differences of the bone marrow (BM) hematopoietic progenitor cells in autoimmune hepatitis type-1 (AIH-1) and primary biliary cirrhosis (PBC). In order to better investigate the possible involvement of BM in these diseases, we studied the morphological abnormalities of BM aspirates in the same patients with AIH-1 and PBC.

METHODS

BM smears from 13 AIH-1 and 13 PBC patients were investigated. BM from 12 patients with cirrhosis of non-autoimmune etiology and eight healthy individuals served as pathological (PC) and healthy controls (HC).

RESULTS

Erythroid, granulocyte and platelet precursors were variably altered. Polychromatic normoblasts and immature megakayocytes were higher in AIH-1 (11.9 +/- 2.9 and 16.2 +/- 16.9, respectively) and PBC (10.2 +/- 3.6 and 17.3 +/- 20.2, respectively) compared to PC (7 +/- 2 and 2.3 +/- 6.0, respectively) and HC (7.9 +/- 1.6 and 0 +/- 0, respectively) (P = 0.0001 and P = 0.006). In AIH-1, immature megakaryocytes were significantly higher in patients receiving immunosuppression (25.71 +/- 17.66 vs 5.00 +/- 5.48; P < 0.02) and were associated negatively with laboratory markers of disease activity. BM plasmacytosis was observed more frequently in AIH-1 compared to PBC and PC. BM monocytosis was found in all patients with AIH-1, PBC and PC whereas approximately half of the patients with autoimmune liver diseases and all PC had BM lymphocytosis.

CONCLUSIONS

BM monocytosis and lymphocytosis are commonly found in AIH-1 and PBC patients irrespective of the presence of cirrhosis or the use of immunosuppression. BM plasmacytosis appears to be a distinct finding in some AIH-1 patients, as similar findings were observed in only one PBC and one PC, whereas BM immature megakaryocytes characterize both AIH-1 and PBC. Whether BM is a target organ in AIH-1 and PBC needs further investigation.

Autoimmune liver serology: Current diagnostic and clinical challenges

Liver-related autoantibodies are crucial for the correct diagnosis and classification of autoimmune liver diseases (AiLD), namely autoimmune hepatitis types 1 and 2 (AIH-1 and 2), primary biliary cirrhosis (PBC), and the sclerosing cholangitis variants in adults and children. AIH-1 is specified by anti-nuclear antibody (ANA) and smooth muscle antibody (SMA). AIH-2 is specified by antibody to liver kidney microsomal antigen type-1 (anti-LKM1) and anti-liver cytosol type 1 (anti-LC1). SMA, ANA and anti-LKM antibodies can be present in de-novo AIH following liver transplantation. PBC is specified by antimitochondrial antibodies (AMA) reacting with enzymes of the 2-oxo-acid dehydrogenase complexes (chiefly pyruvate dehydrogenase complex E2 subunit) and disease-specific ANA mainly reacting with nuclear pore gp210 and nuclear body sp100. Sclerosing cholangitis presents as at least two variants, first the classical primary sclerosing cholangitis (PSC) mostly affecting adult men wherein the only (and non-specific) reactivity is an atypical perinuclear antineutrophil cytoplasmic antibody (p-ANCA), also termed perinuclear anti-neutrophil nuclear antibodies (p-ANNA) and second the childhood disease called autoimmune sclerosing cholangitis (ASC) with serological features resembling those of type 1 AIH. Liver diagnostic serology is a fast-expanding area of investigation as new purified and recombinant autoantigens, and automated technologies such as ELISAs and bead assays, become available to complement (or even compete with) traditional immunofluorescence procedures. We survey for the first time global trends in quality assurance impacting as it does on (1) manufacturers/purveyors of kits and reagents, (2) diagnostic service laboratories that fulfill clinicians’ requirements, and (3) the end-user, the physician providing patient care, who must properly interpret test results in the overall clinical context.

Antimitochondrial antibodies and other antibodies in primary biliary cirrhosis: diagnostic and prognostic value

Antimitochondrial antibodies (AMA) are the serologic cornerstone in the diagnosis of primary biliary cirrhosis (PBC), even if they are not detectable in a proportion of patients, notwithstanding the most sensitive and sophisticated technologies used. To fill in the serologic gap in AMA-negative PBC, there is sound evidence to consider antinuclear antibody (ANA) patterns, such as anti-multiple nuclear dots and anti-membranous/rim-like, as PBC-specific surrogate hallmarks of the disease, and their detection can be considered virtually diagnostic. Furthermore, particular ANA specificities, such as anti-gp210, anti-p62, anticentromere antibodies, and anti-dsDNA, may provide additional diagnostic and prognostic information.