How Does the Immune System Work?

Following the Covid-19 pandemic, many of us have become a lot more familiar with the immune system and the role it plays in protecting us from illness. It’s no surprise that those who have suffered more from the virus are often people with compromised immune responses.

Here we look at the body’s immune system, how it works and the role that it plays in combatting diseases, including cancer.

What is the Immune System?

Our immune system is the first line of defense against foreign invaders like viruses. It’s not contained within a specific organ but is a network of different elements that come together and coordinate to protect the body.

When something like a virus attacks the body, the immune system utilizes a range of organs, tissues cells, and molecules to fight off infection.

The influence and importance of the immune system has long been recognized and, in recent times, we’ve seen developments in immunotherapy to help combat many serious diseases such as cancer.

The Innate Immune System

From the moment we are born, our innate immune system is essentially the rapid response team that helps fight off infection. The cells of the system, called phagocytes, rush out to surround the invading entity and try to kill it. This is a more generalized, catch-all system of defense and for the vast majority of infections, it works well.

The Acquired Immune System

Our adaptive or acquired immunity is slightly different in that it involves the immune system developing a specific response to a particular threat. With the Covid-19 virus, the new vaccine is used to encourage individuals to create the appropriate antibodies to fight the disease, utilizing this adaptive part of the immune system.

These two systems work together to repel foreign invaders to the body and help keep us healthy. Simply put, if the innate system doesn’t work, the adaptive system will develop a more specific response. This latter ability of the immune system is what has helped us develop the technique of immunotherapy to combat diseases such as cancer.

Immunity concept

The Cells and Molecules of the Immune System

The complex array of cells and molecules that combine to protect the body are truly remarkable and perform three main tasks: Identifying the invader, marking it and then destroying it.

The cells involved in the immune system include:

  • Individual B cells tasked with making specific antibodies to fight infection.
  • CD4 helper cells help better direct the response of certain elements such as CD8 killer cells.
  • Dendritic cells have a specific function to consume and digest cancer cells. .
  • T cells ensure that the immune response isn’t overreacting and causing more harm than good.

Molecules also play a role in the immune response. The two main ones are antibodies and cytokines. Antibodies are proteins that attach to dangerous invaders such as tumor cells or viruses and mark them for destruction. Cytokines are essentially messengers that ensure the immune cells coordinate together to produce an optimal response.

The Tissues and Organs of the Immune System

Several tissues and organs are involved in maintaining an effective immune system:

  • The appendix is thought to store good bacteria and helps promote a healthy gut.
  • Bone marrow is responsible for creating a whole range of different cells including those that are used for the immune system.
  • Small glands called lymph nodes are found all around the body and filter out viruses and cancer cells so they can be destroyed.
  • The spleen filters the blood and store platelets, helping B cells to multiply.
  • The thymus gland in the chest provides a nursery where new immune cells mature.

The Importance of the Immune System in Immunotherapy

One of the most exciting developments in modern medicine has been the use of immunotherapy to boost the body’s natural defenses against cancer cells.

Immune cells are often found around tumors and can slow or even prevent them from developing. Cancer cells, however, often change in response to attacks from the immune system and can even turn off immune cells themselves.

The role of this type of therapy is to strengthen the immune response so that elements of are more effective in killing the cells. This can be done in a variety of ways:

  • Immune checkpoint inhibitors act to prevent the immune system from being dampened down and allow it to produce a stronger response.
  • T-cell transfer therapy takes cells that are producing an immune response around a tumor, removes them, augments them so they are more efficient and then replaces them.
  • Monoclonal antibodies are manufactured in the lab and are introduced to the body where they bind to specific targets on cancer cells.

In addition, there are vaccines and immune system modulators that can be used to boost the body’s natural immune response.

The immune system provides an incredible defence against attacks to our health, so it’s extremely important that we do all we can to help strengthen and balance it, to ensure it is kept in top fighting condition.