Platelet production and destruction in liver cirrhosis.

BACKGROUND & AIMS: Thrombocytopenia is common in liver cirrhosis (LC) but the mechanisms are not fully understood. The purpose of our work was to evaluate platelet kinetics in LC with different etiologies by examining platelet production and destruction. METHODS: Ninety-one consecutive LC patients (36 HCV, 49 alcoholics, 15 HBV) were enrolled. As controls, 25 subjects with idiopathic thrombocytopenic purpura, 10 subjects with aplastic anemia, and 40 healthy blood donors were studied. Plasma thrombopoietin (TPO) was measured by ELISA. Reticulated platelets (RP) were determined using the Thiazole Orange method. Plasma glycocalicin (GC) was measured using monoclonal antibodies. Platelet associated and serum antiplatelet antibodies were detected by flow cytometry. B-cell monoclonality in PBMC was assessed by immunoglobulin fingerprinting. RESULTS: Serum TPO was significantly lower in LC (29.9±18.1 pg/ml) compared to controls (82.3±47.6 pg/ml). The GC levels were higher in LC (any etiology) than in healthy cases. Conversely, the absolute levels of RP were lower in LC (any etiology) than in healthy controls. The platelet-associated and serum anti-platelet antibodies were higher in HCV+ LC compared to healthy subjects (p<0.0064), alcoholic LC (p<0.018), and HBV+ LC (p<0.0001). B-cell monoclonality was found in 27% of the HCV+LC, while it was not found in HBV+ or alcoholic LC. CONCLUSIONS: Patients with LC present decreased plasma TPO, accelerated platelet turnover, and reduced platelet production. This indicates that LC thrombocytopenia is a multifactorial condition involving both increased platelet clearance and impaired thrombopoiesis.

Activation of naïve B lymphocytes via CD81, a pathogenetic mechanism for hepatitis C virus-associated B lymphocyte disorders.

Infection with hepatitis C virus (HCV), a leading cause of chronic liver diseases, can associate with B lymphocyte proliferative disorders, such as mixed cryoglobulinemia and non-Hodgkin lymphoma. The major envelope protein of HCV (HCV-E2) binds, with high affinity CD81, a tetraspanin expressed on several cell types. Here, we show that engagement of CD81 on human B cells by a combination of HCV-E2 and an anti-CD81 mAb triggers the JNK pathway and leads to the preferential proliferation of the naïve (CD27-) B cell subset. In parallel, we have found that B lymphocytes from the great majority of chronic hepatitis C patients are activated and that naïve cells display a higher level of activation markers than memory (CD27+) B lymphocytes. Moreover, eradication of HCV infection by IFN therapy is associated with normalization of the activation-markers expression. We propose that CD81-mediated activation of B cells in vitro recapitulates the effects of HCV binding to B cell CD81 in vivo and that polyclonal proliferation of naïve B lymphocytes is a key initiating factor for the development of the HCV-associated B lymphocyte disorders.

Comparable functions of plasmacytoid and monocyte-derived dendritic cells in chronic hepatitis C patients and healthy donors.

BACKGROUND/AIMS: Dendritic cells (DCs) play a key role in immune responses through antigen presentation and cytokine secretion. Hepatitis C virus (HCV) is able to escape elimination by the immune system and often establishes a chronic infection. To investigate whether DC dysfunction is involved in this process, we have studied monoycte-derived DCs (Mo-DCs) and plasmacytoid DCs (pDCs), which produce large amounts of IFN-alpha, from chronic HCV patients and healthy donors. METHODS: We have assessed TNF-alpha and IFN-alpha production by pDCs using intracellular staining after total PBMCs stimulation with unmethylated CG dinucleotides (CpGs). The induction of allogeneic T cell proliferation by immature Mo-DCs was measured using the MLR assay. The up-regulation of maturation markers and the production of TNF-alpha in response to LPS were analyzed using flow cytometry and ELISA, respectively. RESULTS: We have detected comparable frequencies of pDCs producing TNF-alpha and IFN-alpha in both chronic HCV patients and healthy donors and we have found that immature Mo-DCs from both patients and donors similarly induce allogeneic T cell proliferation and mature and secrete TNF-alpha in response to LPS. CONCLUSIONS: Our results demonstrate that both pDC and Mo-DCs are not impaired in HCV infected patients.

Interferon plus ribavirin in patients with hepatitis C virus positive mixed cryoglobulinemia resistant to interferon.

OBJECTIVE: Only a small fraction of patients with hepatitis C virus (HCV) positive mixed cryoglobulinemia achieve longterm recovery after interferon (IFN) therapy; we evaluated the effectiveness and safety of combination therapy (interferon plus ribavirin) in nonresponders or those who relapsed after one or more courses of IFN. METHODS: Twenty-seven patients with HCV positive mixed cryoglobulinemia were studied. All were treated with IFN-a2b (3 MU 3 times weekly) for one year, plus daily oral ribavirin 1000 or 1200 mg. RESULTS: Five patients (18.5%) obtained complete recovery from viral infection and from all signs and symptoms of disease. During treatment, most patients (85%) improved clinically. All 5 responders were "relapsers" to the first treatment(s). CONCLUSION: Combination therapy of IFN plus ribavirin could be useful for patients with mixed cryoglobulinemia resistant to IFN as monotherapy.