What do the types of T Cells do?

Cytotoxic T Cells

Cytotoxic T cells play a pivotal role in directly eliminating intracellular pathogens and destroying mutated and cancerous cells. 

Cytotoxic T cells are a part of the adaptive immune response and attack foreign invaders when activated by an antigen. A CD8 receptor, which is present on the surface of all cytotoxic T cells, interacts with cells known as major histocompatibility complex (MHC) Class I molecules to recognize when healthy cells are infected. On recognizing an infected cell, the CD8 receptor activates the cytotoxic T cell, which immediately works to destroy the pathogen by releasing cytotoxic granules into the target cell. Each cytotoxic T cell is unique and designed to fight only one type of antigen.

Helper T cells

Helper T cells are an important part of the adaptive immune response and are required for almost all adaptive immune responses. On sensing when there’s an infection in the body, helper T cells activate cytotoxic T cells to kill the foreign pathogen and fight the infection. Helper T cells also play an important role in activating B cells to secrete antibodies and macrophages to eliminate ingested microbes. 

Helper T cells are activated by a CD4 receptor on the cell surface. The CD4 receptor interacts with MHC (major histocompatibility complex) class II molecules, which are capable of sensing the presence of a foreign pathogen or infection in the body. The CD4 receptor and MHC class II molecules together activate the helper T cells. The activated helper T cells releases cytokines, a type of signaling molecule, which sends a message to the cytotoxic T cells, activating them to fight the infection.  

Regulatory T cells

Regulatory T cells (suppressor cells) are responsible for regulating T cell activity. When the infection is over, regulatory T cells reduce or suppress the activity of T cells, preventing them from attacking healthy cells in the body.