Biomaterial Database

Chronic infections with hepatotropic viruses: mechanisms of impairment of cellular immune responses. 2007

Barbara Rehermann

Immunology Section, Liver Diseases Branch, NIDDK, National Institutes of Health, DHHS, Bethesda, Maryland 20892, USA.

Chronic hepatitis B and C cause significant morbidity and mortality worldwide. Antiviral therapy suppresses but does not eliminate chronic hepatitis B virus (HBV) infection, and it is effective in only half of all hepatitis C virus (HCV)-infected patients. Because adaptive immune responses are associated with spontaneous resolution of acute HBV and HCV infection, therapeutic enhancement of immune responses has been proposed as alternative or supplementary therapy for chronic infection. However, all efforts have been hampered by poor proliferation and effector functions of HBV- and HCV-specific CD4 and CD8 T cells, which are thought to be due to T cell exhaustion, high antigenic load, and viral escape. Recent studies revealed that endogenous factors, such as regulatory T cells, immunosuppressive cytokines, and inhibitory receptors, also contribute to the impairment of virus-specific T cell responses in chronic infection, perhaps reflecting the host's attempt to protect itself against immune-mediated pathology. These endogenous mechanisms and potential avenues to revert them are the subject of this review.

UI	MeSH Term	Description	Entries
D007111	Immunity, Cellular	Manifestations of the immune response which are mediated by antigen-sensitized T-lymphocytes via lymphokines or direct cytotoxicity. This takes place in the absence of circulating antibody or where antibody plays a subordinate role.	Cell-Mediated Immunity,Cellular Immune Response,Cell Mediated Immunity,Cell-Mediated Immunities,Cellular Immune Responses,Cellular Immunities,Cellular Immunity,Immune Response, Cellular,Immune Responses, Cellular,Immunities, Cell-Mediated,Immunities, Cellular,Immunity, Cell-Mediated,Response, Cellular Immune
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000998	Antiviral Agents	Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.	Antiviral,Antiviral Agent,Antiviral Drug,Antivirals,Antiviral Drugs,Agent, Antiviral,Agents, Antiviral,Drug, Antiviral,Drugs, Antiviral
D013601	T-Lymphocytes	Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.	T Cell,T Lymphocyte,T-Cells,Thymus-Dependent Lymphocytes,Cell, T,Cells, T,Lymphocyte, T,Lymphocyte, Thymus-Dependent,Lymphocytes, T,Lymphocytes, Thymus-Dependent,T Cells,T Lymphocytes,T-Cell,T-Lymphocyte,Thymus Dependent Lymphocytes,Thymus-Dependent Lymphocyte
D015496	CD4-Positive T-Lymphocytes	A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes.	T4 Cells,T4 Lymphocytes,CD4-Positive Lymphocytes,CD4 Positive T Lymphocytes,CD4-Positive Lymphocyte,CD4-Positive T-Lymphocyte,Lymphocyte, CD4-Positive,Lymphocytes, CD4-Positive,T-Lymphocyte, CD4-Positive,T-Lymphocytes, CD4-Positive,T4 Cell,T4 Lymphocyte
D016207	Cytokines	Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.	Cytokine
D018414	CD8-Positive T-Lymphocytes	A critical subpopulation of regulatory T-lymphocytes involved in MHC Class I-restricted interactions. They include both cytotoxic T-lymphocytes (T-LYMPHOCYTES, CYTOTOXIC) and CD8+ suppressor T-lymphocytes.	Suppressor T-Lymphocytes, CD8-Positive,T8 Cells,T8 Lymphocytes,CD8-Positive Lymphocytes,Suppressor T-Cells, CD8-Positive,CD8 Positive Lymphocytes,CD8 Positive T Lymphocytes,CD8-Positive Lymphocyte,CD8-Positive Suppressor T-Cell,CD8-Positive Suppressor T-Cells,CD8-Positive Suppressor T-Lymphocyte,CD8-Positive Suppressor T-Lymphocytes,CD8-Positive T-Lymphocyte,Cell, T8,Cells, T8,Lymphocyte, CD8-Positive,Lymphocyte, T8,Lymphocytes, CD8-Positive,Lymphocytes, T8,Suppressor T Cells, CD8 Positive,Suppressor T Lymphocytes, CD8 Positive,Suppressor T-Cell, CD8-Positive,Suppressor T-Lymphocyte, CD8-Positive,T-Cell, CD8-Positive Suppressor,T-Cells, CD8-Positive Suppressor,T-Lymphocyte, CD8-Positive,T-Lymphocyte, CD8-Positive Suppressor,T-Lymphocytes, CD8-Positive,T-Lymphocytes, CD8-Positive Suppressor,T8 Cell,T8 Lymphocyte
D019694	Hepatitis B, Chronic	INFLAMMATION of the LIVER in humans caused by HEPATITIS B VIRUS lasting six months or more. It is primarily transmitted by parenteral exposure, such as transfusion of contaminated blood or blood products, but can also be transmitted via sexual or intimate personal contact.	Chronic Hepatitis B,Chronic Hepatitis B Virus Infection,Hepatitis B Virus Infection, Chronic
D019698	Hepatitis C, Chronic	INFLAMMATION of the LIVER in humans that is caused by HEPATITIS C VIRUS lasting six months or more. Chronic hepatitis C can lead to LIVER CIRRHOSIS.	Chronic Hepatitis C