Suppressor T Cells

Table of Contents

What are Suppressor T cells?

Suppressor T cells, which are now known as regulatory T cells, are a type of T cells that are found in the immune system. It is denoted as T_reg. It helps in preventing autoimmune diseases and maintaining tolerance for self-antigens. They are immunosuppressive in nature and thus suppress the proliferation and induction of effector T cells. The T_reg cells are derived from the same lineage as the naive CD4⁺ cells, and hence, it becomes difficult to differentiate between both cell types. However, a cytokine named TGF-β helps in the maintenance of homeostasis of T_reg cells and also differentiates them from the CD4⁺ cells.

Population of Suppressor T Cells

The suppressor T cells are an important constituent of the immune system that suppresses the response of other immune cells. It is a self-check mechanism that checks and blocks any excessive reactions. The T_reg cells exist in many forms; they express CD25, CD4 and FOXP3 regulatory cells. They function to block the ongoing immune response after the invading pathogen has been eliminated and also prevent autoimmune responses.

Functions

When our immune system is not able to differentiate between self and non-self, it starts to destroy tissues and cells of our own, and this condition gives rise to autoimmune diseases. T_reg cells function to block the immune reaction and suppress the self-reactivity of the immune system. The mechanism of suppression by the suppressor T cells has not been clearly understood, but below are some proposed mechanisms:

• They suppress the immune response by secreting inhibitory cytokines, such as IL-35, IL-10 and TGF-β.
• They produce Granzyme B that induces apoptosis in effector T cells.
• It induces reverse signalling in dendritic cells by direct interaction and produces indoleamine 2,3-dioxygenase that is immunosuppressive in nature.
• It also initiates IL-2 negative feedback loops such that they alert the T_reg cells about high immune activity, and hence, immunosuppressive action is induced.

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• Difference between B Cells and T Cells – An Overview
• T Lymphocytes – Definition, Production and Types
• Allergies and Autoimmunity – Similarities and Its Differences