Academic journal article Alcohol Research: Current Reviews

Impact of Alcohol Abuse on the Adaptive Immune System

Academic journal article Alcohol Research: Current Reviews

Impact of Alcohol Abuse on the Adaptive Immune System

Article excerpt

Alcohol exposure, and particularly chronic heavy drinking, affects all components of the adaptive immune system. Studies both in humans and in animal models determined that chronic alcohol abuse reduces the number of peripheral T ceils, disrupts the balance between different T-cell types, influences T-cell activation, impairs T-cell functioning, and promotes T-cell apoptosis. Chronic alcohol exposure also seems to cause loss of peripheral B cells, while simultaneously inducing increased production of immunoglobulins. In particular, the levels of antibodies against liver-specific auto-antigens are increased in patients with alcoholic liver disease and may promote alcohol-related liver damage. Finally, chronic alcohol exposure in utero interferes with normal T-cell and B-cell development, which may increase the risk of infections during both childhood and adulthood. Alcohol's impact on T cells and B cells increases the risk of infections (e.g., pneumonia, HIV infection, hepatitis C virus infection, and tuberculosis), impairs responses to vaccinations against such infections, exacerbates cancer risk, and interferes with delayed-type hypersensitivity. In contrast to these deleterious effects of heavy alcohol exposure, moderate alcohol consumption may have beneficial effects on the adaptive immune system, including improved responses to vaccination and infection. The molecular mechanisms underlying ethanol's impact on the adaptive immune system remain poorly understood.

Key words: Alcohol use, abuse and dependence; alcohol use disorder; heavy drinking; beneficial moderate alcohol consumption; ethanol consumption; prenatal alcohol exposure; alcoholic liver disease; immune system; adaptive immune system; immune response; growth and development; infection; T cells; B cells; lymphocyte; immunoglobulin; vaccinations; cancer; pneumonia; HIV; hepatitis C virus; tuberculosis; human studies; animal models

**********

In the United States, alcohol use disorder (AUD) is the third-leading cause of preventable death. It is associated with increased susceptibility to bacterial pneumonia; viral infections, such as HIV and hepatitis C virus (HCV); and increased postoperative morbidity and mortality. This increased susceptibility is mediated in part by functional alterations in various cells of the immune system. The immune system is broadly divided into two branches: innate and adaptive immunity. The innate immune system represents the first line of host defense and is necessary for inducing the adaptive immune response. The adaptive immune system can be subdivided further into cellular and humoral immunity. The main components of cellular immunity are CD4 and CD8 T cells. CD4 T cells play a critical role in the activation and differentiation of macrophages, CD8 T cells, and B cells. CD8 T cells, on the other hand, are essential for eliminating cells infected with intracellular pathogens, as well as cancer cells. Humoral immunity is mediated by B cells, which produce antibodies to eliminate extracellular microorganisms and prevent spread of infections. This review will summarize the impact of chronic heavy drinking or AUD as well as of moderate alcohol consumption on adaptive immunity and discuss future areas of research in this rapidly evolving field.

Impact of AUD on T Cells

Effects on T-Cell Numbers, Phenotype, and Activation

T cells constitute a diverse population of lymphocytes that develop in the bone marrow and mature in the thymus. Each T cell expresses a unique T-cell receptor (TCR) that confers specificity for one particular foreign molecule (i.e., antigen). Early studies already had indicated that chronic alcohol abuse (i.e., for 12 to 15 years) resulted in reduced numbers of peripheral T cells (Liu 1973; McFarland and Libre 1963). More recent studies confirmed this observation and showed that the lack of lymphocytes (i.e., lymphopenia) was as severe in people who engaged in a short period of binge drinking as it was in individuals who drank heavily for 6 months (Tonnesen et al. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.