Non-corticosteroid immunosuppressants and immunotherapies

Non-corticosteroid immunosuppressants are a class of medications that suppress the immune system and they’re used primarily to reduce the immune response after organ transplantation and inorder to prevent transplant rejection.

Imagine the immune system as an army ready to fight against anything foreign that might cause harm like microorganisms and toxins but without harming the body’s own cells. To make that work, the immune system is trained to distinguish non-self or foreign, from self.

The soldiers of the army are our immune cells which are basically white blood cells.

A specific type of the immune cells are the T cells and there are two main types: cytotoxic T cells and helper T cells.

Cytotoxic T cells kill infected or cancerous cells, whereas T helper cells primarily support other immune cells.

These cells like the generals on the battlefield: they secrete cytokines that coordinate the efforts of all the immune cells and that explains why immunosuppressants primarily act by inhibiting their action.

Okay but first things first. When a T cell is initially formed it’s considered naive but later when that T cell encounters an antigen, it gets activated and turns into an effector T cell. This process requires two signals.

The first signal is the antigen itself, which is usually presented to the helper T cell by an antigen presenting cell like a macrophage.

The second signal is called costimulation, and it’s when a ligand called CD28 on the surface of a T cell binds to a ligand called B7 on the antigen presenting cell.