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CD4 T cell
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The CD4 T cell is a white blood cell that is also called the helper T cell. It got that name from a piece it carries on its surface, the CD4 coreceptor, which is what sets it apart from its siblings.
Its job is to read and to give orders. Other cells show it small pieces of what they ran into, mounted on platforms called MHC class 2, which work like serving trays. When the CD4 cell recognizes something foreign on that tray, it activates and releases cytokines, chemical messages that wake up the rest of the immune system. It is a conductor who does not play a single instrument, but cues each section in.
Depending on what each one handles, they get a last name. TH1 cells switch on macrophages, the cells that eat invaders, and they work against infections that hide inside cells. TH2 cells fight helminths, which are parasitic worms. And TH17 cells guard the mucosal surfaces, the moist surfaces of the body, against fungi and against the bacteria that stay outside cells, the extracellular ones.
In brief
The CD4 T cell, or helper T cell, is an effector cell of cell-mediated immunity, set apart by the CD4 coreceptor it carries.
It recognizes antigens presented on MHC class 2 molecules and, once activated, makes cytokines that set other immune cells in motion.
A conductor who does not play, but cues each section in.
It comes in subtypes: TH1 cells activate macrophages against intracellular infections, TH2 cells fight helminths, and TH17 cells defend the mucosal surfaces against extracellular bacteria and fungi.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingHistology, T-Cell Lymphocyte, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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