What is the Difference Between BALT GALT and MALT

The key difference between BALT GALT and MALT is that BALT is located within the bronchial submucosa while GALT is located within the mucosa, submucosa, and lamina propria of the small intestine, and MALT is located in different submucosal membrane sites of the body.

Lymphoid tissue is a type of tissue that makes up the lymphatic system, which in turn supports the immune system of the body. The lymphoid tissue is mainly involved in protecting the body from different disease-causing invading pathogens, absorbing fats from the digestive tract, maintaining the fluid balance of the body, and removing cellular waste. Depending on the location of the lymphoid tissue, it has many types. BALT, GALT, and MALT are three such types.

CONTENTS

1. Overview and Key Difference
2. What is BALT  
3. What is GALT 
4. What is MALT
5. Similarities – BALT GALT and MALT
6. BALT vs GALT vs MALT in Tabular Form
7. Summary – BALT vs GALT vs MALT

What is BALT (Bronchus Associated Lymphoid Tissue)?

BALT stands for bronchus associated lymphoid tissue, which is a tertiary lymphoid structure. BALT is a subcategory of mucosa-associated lymphoid tissue. BALT is present in the lungs and bronchus and consists of lymphoid follicles. BALT is usually present along the bifurcation of the upper bronchi beneath the epithelium. It usually lies between an artery and a bronchus. It is an effective priming site for both systemic and mucosal immune responses. The structure of BALT is similar to many mammalian species. But the inducibility and maintenance differ from organism to organism. In rabbits and pigs, BALT is a normal component in the lungs and bronchus. But in mice and humans, BALT appears only after inflammation or an infection. Hence, it is referred to as inducible BALT or iBALT.

The exact functional pathway of BALT in humans is not clearly identified yet since the formation of an immune response is unclear. But the general function of BALT is to protect the lungs and bronchus from invading pathogens.

What is GALT (Gut Associated Lymphoid Tissue)?

GALT stands for gut associated lymphoid tissue and is another subcategory of mucosa-associated lymphoid tissue. GALT is present throughout the lining of the intestine. GALT consists of a large population of plasma cells and makes up about 70% of the immune system by weight. Hence, GALT is an extremely important immune unit to fight against pathogens derived from the intestines. Therefore, GALT significantly affects the strength of the whole immune system. In the intestine, GALT gets separated from the intestine lumen and its content by the intestine mucosa covered by a layer of epithelial cells. In the small intestine, GALT includes Peyer’s patches. It is an aggregated lymphoid tissue penetrating the lumen and acts as a crucial site for the initiation of immune responses in the gut.

What is MALT (Mucosa Associated Lymphoid Tissue)?

MALT stands for mucosa associated lymphoid tissue, which is a diffuse system of lymphoid tissue present in different submucosal membrane sites of the body. These sites include the gastrointestinal tract, nasopharynx, lung, thyroid, salivary glands, eyes, and skin. Lymphocytes such as T cells, B cells, macrophages, and plasma cells are present abundantly in MALT. All lymphocytes capture antigens that pass through the mucosal epithelium to generate an immune response where it is necessary. 50% of the lymphoid tissue in the human body is comprised of MALT.

Subdivisions of MALT include gut-associated lymphoid tissue (GALT), bronchus-associated lymphoid tissue (BALT), nasal-associated lymphoid tissue (NALT), conjunctival-associated lymphoid tissue (CALT), larynx associated lymphoid tissue (LALT), skin-associated lymphoid tissue (SALT), etc. The function of MALT is to regulate mucosal immunity.

What are the Similarities Between BALT GALT and MALT?

• BALT, GALT, and MALT are lymphatic tissues.
• They belong to the lymphatic system.
• Moreover, all tissues are associated with generating immune responses.
• BALT, GALT, and MALT strengthen the immunity system.
• All three are present as lining to the specific locations around organ systems.

What is the Difference Between BALT GALT and MALT?

BALT is a tertiary lymphoid structure which is a subcategory of mucosa-associated lymphoid tissue located within the bronchial submucosa, while GALT is a subcategory of mucosa-associated lymphoid tissue that is present throughout the lining of the intestine, and MALT is a diffuse system of lymphoid tissue present in different submucosal membrane sites of the body. Thus, this is the key difference between BALT GALT and MALT. The general function of BALT is to protect the lungs and bronchus from invading pathogens, while the function of GALT is to protect the body from invading pathogens in the gut. In contrast, the function of MALT is to regulate mucosal immunity.

The below infographic presents the differences between BALT GALT and MALT in tabular form for side by side comparison.

Summary – BALT vs GALT vs MALT

Lymphoid tissue supports the immune system of the body. BALT, GALT, and MALT are three lymphoid tissues. BALT is present in the lungs and bronchus and consists of lymphoid follicles. It is an effective priming site for both systemic and mucosal immune responses. GALT is present throughout the lining of the intestine. GALT consists of a large population of plasma cells and makes up about 70% of the immune system by weight. MALT is a diffuse system of lymphoid tissue present in different submucosal membrane sites of the body. The function of MALT is to regulate mucosal immunity. So, this summarizes the difference between BALT GALT and MALT.

Reference:

1. “Bronchus-associated lymphoid tissue (BALT) histology and its role in various pathologies.” Intechopen.
2. “Gut-associated lymphoid tissue.” Science Direct.
3. “Mucosa-associated lymphoid tissue.” Science Direct.

Image Courtesy:

1. “IBALT of mice” By James A. Wiley, Laura E. Richert, Steve D. Swain, Ann Harmsen, Dale L. Barnard, Troy D. Randall, Mark Jutila, Trevor Douglas, Chris Broomell, Mark Young, Allen Harmsen – (CC BY-SA 4.0) via Commons Wikimedia
2. “2210 Mucosa Associated Lymphoid Tissue (MALT) Nodule” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia