Organs in the Immune System

Keeping your body out of harm is an enormous task of the immune system where it has to fight off disease-causing microbes and toxins every moment in your daily life and for the rest of your life. But before I get into the Organs involved in the immune system you need to understand a little bit about the Lymphatic System, which is an integral part of your immune health, function, and organs.

Brief Overview of the Lymphatic System

The lymphatic system consists of the following:

  1. Lymph
  2. Lymphatic vessels
  3. Lymphatic tissues and immune cells producing organs

In immunology study, they are divided into two types of sections in the lymphatic system, and they are:

1- Primary Lymphatic Organs

  • Redbone marrows
  • Thymus

2-Secondary Lymphatic Organs and Tissues 

  • Lymph nodes
  • Lymphatic nodules
  • Spleen

 So the primary organs in the immune system are red bone marrow, thymus, lymph nodes, lymphatic nodules, and the spleen. They all have significant involvements in establishing the immune system regarding its healthy function. Let’s see each of the immune organs’ primary role(s).

Red Bone Marrow

In redbone, the marrow organ is basically where stem cells develop, next they differentiate into several kinds of cells like red blood cells and immune system cells like eosinophils, monocytes, neutrophils, and basophils.


In the thymus organ, there are T cells, dendritic cells, macrophages, and epithelial cells. The thymus plays an important role where immature T cells leave the red bone marrow to the thymus to increase in number and change to mature T cells. Think of it as they are uneducated immune cells, and they get their education in the thymus organ and graduate to be fully prepared to Killer T-cells and Helper T-cells as part of the immune system soldiers so to speak.    

Lymph Nodes

Lymph nodes resemble the shape of beans, and there are about 600 of them spread throughout the body. Depending on their locations in the body, lymph nodes supply immune defenders called B-cells. And these cells change to different cells like macrophages, T cells, plasma cells, and dendritic cells.

When lymph (means clear liquid) gets in/enter the lymph nodes there are microbial pathogens and toxins where they get trapped so macrophages can destroy them. At the same time, there is another immune cell defender called Lymphocyte which has a similar role in killing pathogens. Therefore, the lymph nodes’ primary task is to filter the clear liquid or lymph from getting rid of these harmful objects.   

Lymphatic Nodules

Lymphatic nodules are part of the lymphatic tissues, and they have an egg shape resemblance. These lymphatic nodules are located in large number in the mucous membranes lining of:

  1. Urinary tract
  2. Gastrointestinal tract
  3. Reproductive tract
  4. Respiratory airways

Lymphatic nodules are usually small and exist as individuals. However, not all of the nodules are like that. Some of the lymphatic nodules are together as a big cluster, and a good example is the tonsils. Tonsils are located inside the throat in a strategic location as part of the immune system function against inhaling air that is full of foreign objects and toxins, and the same thing is eating food.


The spleen is another immune system organ that plays an important role and it is the largest of the lymphatic tissues. It contains two kinds of tissues that are called:

  • White pulp: it contains mostly two immune system cells, they are macrophages and lymphocytes.   
  • Red pulp: it consists of red blood cells, plasma cells, lymphocytes, macrophages, and leukocytes (granular type).

Wrap Up

These are the organs involved in the immune system that need to stay healthy through eating healthy by focusing on immune-boosting foods and other equally important factors that I discuss throughout the website.  I hope you also have a basic yet essential understanding of the functions of the immune system organs.