Programmed hepatocytes cell death associated with FLIP downregulation in response to extracellular preS1/2.

Chronic hepatitis B virus (HBV) infection involves liver damage resulting in continuous cell injury and death. During HBV infection, hepatocytes exhibit changes in death receptor expression and in their susceptibility to death. These changes are observed not only in infected cells but also in bystander cells.

Altered T cell costimulation during chronic hepatitis B infection.

T-cell response to hepatitis B virus (HBV) is vigorous, polyclonal and multi-specific in patients with acute hepatitis who ultimately clear the virus, whereas it is narrow and inefficient in patients with chronic disease, where inappropriate early activation events could account for viral persistence. We investigated the induction of activation receptors and cytokine production in response to HBcAg and crosslinking of CD28 molecules, in CD4+ cells from a group of chronically infected patients (CIP) and naturally immune subjects (NIS). We demonstrated that CD4+ cells from CIP did not increase levels of CD40L and CD69 following stimulation with HBcAg alone or associated to CD28 crosslinking, in contrast to subjects that resolved the infection (p<0.

[Impaired activation and costimulation of T CD4+ lymphocytes during chronic hepatitis C infection].

Hepatitis C chronic infection occurs in 80% of the cases and eventually leads to cirrhosis and hepatocellular carcinoma. A deficient adaptive immune response has been described during chronic infection which contributes to viral persistence. This altered T cell response could be associated to deficient costimulation signals during priming of T cells.

CD40/CD40L expression in leukocytes from chronic granulomatous disease patients.

Chronic granulomatous disease (CGD) is an inherited disorder caused by defects in the NADPH oxidase complex, which generates superoxide, the precursor of hydrogen peroxide (H(2)O(2)) and other reactive oxygen derivatives with microbicidal activity. Because CGD patients are at risk of chronic inflammatory manifestations, including inflammatory bowel disease and autoimmune diseases, and it is not clear whether these pathologies are exclusively secondary to altered superoxide production, or whether distinct immunologic defects are involved, we explored cell proliferation, lymphocyte cell counts, immunoglobulin levels, presence of autoimmune antibodies and expression of costimulatory molecules in leukocytes from CGD patients. We found that CGD patients have a diminished phytohemagglutinin-induced proliferation of blood mononuclear cells.

Antigen-induced regulatory T cells in HBV chronically infected patients.

T cell response against HBV is vigorous in patients with acute hepatitis who clear the virus, whereas it is weak and narrowly focused in patients with chronic disease. We report that following incubation with HBcAg, a population of CD4+FoxP3+ cells expressing phenotypic markers of both natural and induced Tregs, can be antigen-induced from peripheral mononuclear cells. Conversely, naive and naturally immune subjects did not increase CD4+FoxP3+ Tregs following stimulation with HBcAg, supporting the idea that natural Tregs are able to respond specifically to HBV antigen.

[Pattern of T cell activation in absence of protective immunity against hepatitis B virus. Review].

Hepatitis B is an important cause of morbidity and mortality around the world. One-third of the world's population has been estimated to be infected with hepatitis B virus (HBV). A significant amount of evidence suggests that both humoral and cellular immune responses are important to eliminate the virus and that, cellular immunity is involved in the pathogenesis of the disease.

[Role of human immunodeficiency virus in leukocytes apoptosis from infected patients].

The hallmark of the immunodeficiency virus infection is a progressive detriment of the immune response which has been associated to a gradual loss of its responsible components, in particularly, CD4 positive T cells. Although this cell population is considered the main target of the virus, there is a recent deal of interest in studying other components that may not be targets of the virus, but are important elements to control infectious microorganisms and that have been demonstrated to be altered during HIV infection. Neutrophils (PMN) are innate immune components that play a fundamental role against HIV infection and these cells have been described as functionally altered during AIDS.

Prevention of central venous catheter-related bloodstream infections using non-technologic strategies.

Objective: To evaluate the incidence of nosocomial bacteremias related to the use of non-impregnated central venous catheters (CVCs) when only non-technologic strategies were used to prevent them.

Design: This was a prospective study of infectious complications of CVCs placed in intensive care unit (ICU) patients from April 1997 to December 2001.

Setting: The medical-surgical ICU of a tertiary-care, university-affiliated hospital in Argentina.