Introduction: If we’ve had mumps when we are as a child, there after we become immune to mumps and we are not susceptible to a second episode of mumps.  Due to the natural exposure to the disease we acquired this immunity. If we are vaccinated or immunized, we acquire immunity through artificial means.

Our immune system discriminates self and foreign antigens and responds accordingly. This is like how our defense/security people identify the illegal foreign invaders at our borders and kill them.

In some individuals due to various reasons their immune system fails, and start producing antibodies against their own self antigens/cells. This is like our own defense/security people turn towards us and attack on us instead of protecting. This type of immune response is called as Autoimmunity (against self/our own). The disease produced due to such response is called as autoimmune diseases.  

How does our immune system work:

*Cell mediated immune response: It is mounted by the immune system with the help of T cells (T lymphocytes) and macrophages, where they attack the antigen directly.

*Humoral immune response: In collaboration, macrophages activate the T cells, and the T cells activate the B cells (B lymphocytes) to start producing antibodies against the foreign bodies to bring about the destruction of such bodies.

Thus the T cell degree of reactivity play important role in both the above immune responses.

Components of the Immune System:

Macrophages and Neutrophils – Housekeeper and frontline defenders.

T-Cells/Helper T Cells – Commander in chief of the immune system.

T-Cells/Killer T Cells – Recruited and activated by helper T Cells.

T-Cells/Suppressor T Cells – Keeping every thing in control.

B Cells – Biological arms factory which produces antibodies.

Antibodies – Ammunition of the immune system.