Immunology

Scientists tackle two distinct immunological disorders

In two recent studies, a team of scientists reports the mechanisms underlying two distinct immunological disorders affecting children and adults. Stephanie Humblet-Baron (VIB-KU Leuven) was the researcher at the helm of both ...

HIV & AIDS

AIDS—an approach for targeting HIV reservoirs

Current HIV treatments need to be taken for life by those infected as antiretroviral therapy is unable to eliminate viral reservoirs lurking in immune cells. Institut Pasteur scientists have identified the characteristics ...

HIV & AIDS

HIV latency differs across tissues in the body

Mechanisms that govern HIV transcription and latency differ in the gut and blood, according to a study published November 15 in the open-access journal PLOS Pathogens by Steven Yukl of San Francisco Veterans Affairs Medical ...

Medical research

Study reveals new targets to inhibit pulmonary fibrosis

In a study out this week in Science Translational Medicine, an international team led by researchers at Vanderbilt University Medical Center sheds new light on the cause of pulmonary fibrosis and demonstrates a way to impede ...

Immunology

How chronic infections can outsmart the immune system

Professor Simona Stäger and her team at INRS have discovered a mechanism that causes the body to sabotage its own defenses against infection by visceral leishmaniasis, a fatal tropical disease. This discovery could help ...

page 1 from 8

T helper cell

T helper cells (also known as effector T cells or Th cells) are a sub-group of lymphocytes (a type of white blood cell or leukocyte) that play an important role in establishing and maximizing the capabilities of the immune system. These cells are unusual in that they have no cytotoxic or phagocytic activity; they cannot kill infected host (also known as somatic) cells or pathogens, and without other immune cells they would usually be considered useless against an infection. Th cells are involved in activating and directing other immune cells, and are particularly important in the immune system. They are essential in determining B cell antibody class switching, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages. It is this diversity in function and their role in influencing other cells that gives T helper cells their name.

Mature Th cells are believed to always express the surface protein CD4. T cells expressing CD4 are also known as CD4+ T cells. CD4+ T cells are generally treated as having a pre-defined role as helper T cells within the immune system, although there are known rare exceptions. For example, there are sub-groups of regulatory T cells, natural killer T cells, and cytotoxic T cells that are known to express CD4 (although cytotoxic examples have been observed in extremely low numbers in specific disease states, they are usually considered non-existent). All of the latter CD4+ T cell groups are not considered T helper cells, and are beyond the scope of this article.

The importance of helper T cells can be seen from HIV, a virus that infects cells that are CD4+ (including helper T cells). Towards the end of an HIV infection the number of functional CD4+ T cells falls, which leads to the symptomatic stage of infection known as the acquired immune deficiency syndrome (AIDS). There are also some rare disorders that result in the absence or dysfunction of CD4+ T cells. These disorders produce similar symptoms, and many of these are fatal.

This text uses material from Wikipedia, licensed under CC BY-SA