What is the Difference Between Chemotaxis and Diapedesis

The key difference between chemotaxis and diapedesis is that chemotaxis is a process that involves the movement of a cell or an organism in response to a chemical stimulant, while diapedesis is a process that involves the migration of blood cells through the walls of blood vessels into the surrounding tissues in response to tissue damage or an infection.

Chemotaxis and diapedesis are two biological processes that involve the movement or migration of biological cells. Both these processes can be seen when there is inflammation in the body. Understanding their mechanisms is highly important, especially in disease studies.

CONTENTS

1. Overview and Key Difference
2. What is Chemotaxis 
3. What is Diapedesis
4. Similarities – Chemotaxis and Diapedesis
5. Chemotaxis vs Diapedesis in Tabular Form
6. Summary – Chemotaxis vs Diapedesis

What is Chemotaxis?

Chemotaxis is a biological process that involves the movement of a cell or an organism in response to a chemical stimulant. Normally, some somatic cells, bacteria, and single or multicellular organisms move according to chemical stimulants in the environment. Through the mechanism of this process, bacteria can find out food molecules or can flee from poison such as phenol. In multicellular organisms like humans, this process can be identified in early development and late development.

An example of using chemotaxis in early development is the movement of sperm toward eggs during fertilization. An example of using chemotaxis in late development is the movement of neurons and lymphocytes. Moreover, chemotaxis can also be seen in the normal function and health of a multicellular organism. An example of this is the movement of leukocytes during an injury or infection. Furthermore, chemotaxis is divided into two types: positive and negative. Positive chemotaxis occurs if the movement is towards a higher concentration of the chemical question. On the other hand, negative chemotaxis occurs if the movement is in the opposite direction.

However, the mechanisms that allow chemotaxis in animals are usually subverted in cancer metastasis. In addition to that, the aberrant chemotaxis of leukocytes and lymphocytes also contributes to inflammatory diseases in humans, such as atherosclerosis, asthma, and arthritis.

What is Diapedesis?

Diapedesis is a process involving the migration of blood cells through the walls of blood vessels or capillaries into the surrounding tissues in response to tissue damage or an infection. The mechanism of this process is specially used by leukocytes. This is called leukocyte extravasation. In leukocyte extravasation, these cells move out of the circulatory system toward the site of damaged tissues or infection. This process is a part of the innate immunity response. The leukocytes involved in this process are non-specific. The migration of the leukocytes in this process is due to chemokines that are produced by the macrophages in the site of damaged tissues or infection. The diapedesis process further can be divided into 4 main steps: chemoattraction, rolling adhesion, tight adhesion, and transmigration.

Moreover, monocytes also use diapedesis. However, monocytes use this process in the absence of infection or tissue damage. They use diapedesis when they develop into macrophages. Furthermore, the defect in leukocyte extravasation causes a disease called leukocyte adhesion deficiency (LAD). People with LAD have recurrent bacterial infections, impaired wound healing, and neutrophilia.

What are the Similarities Between Chemotaxis and Diapedesis?

• Chemotaxis and diapedesis are two biological processes involved in the movement or migration of biological cells.
• Both these processes can be seen in the inflammation in the body.
• Leukocytes use both of these processes.
• Impairment of both these processes leads to diseases.

What is the Difference Between Chemotaxis and Diapedesis?

Chemotaxis is a process that involves the movement of a cell or an organism in response to a chemical stimulant, while diapedesis is a process that involves the migration of blood cells through the walls of blood vessels into the surrounding tissues in response to tissue damage or an infection. Thus, this is the key difference between chemotaxis and diapedesis. Furthermore, chemotaxis is mainly used by somatic cells, bacteria, and single or multicellular organisms, while diapedesis is mainly used by leukocytes and monocytes.

The below infographic presents the differences between chemotaxis and diapedesis in tabular form for side-by-side comparison.

Summary – Chemotaxis vs Diapedesis

Chemotaxis and diapedesis are two biological processes that involve the movement or migration of biological cells. These processes are widely observed during inflammation in the human body. Chemotaxis involves moving a cell or an organism in response to a chemical stimulant, while diapedesis involves the migration of blood cells through the walls of blood vessels into the surrounding tissues in response to tissue damage or an infection. So, this summarizes the difference between chemotaxis and diapedesis.

Reference:

1. Jin, Tian, et al. “Chemotaxis, Chemokine Receptors and Human Disease.” U.S. National Library of Medicine, Oct. 2008.
2. Filippi, Marie-Dominique. “Mechanism of Diapedesis: Importance of the Transcellular Route.” Advances in Immunology, U.S. National Library of Medicine, 2016.

Image Courtesy:

1. “Chemotaxis1” By Fortinda – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Leukocyte-extravasation” By Zachary P. Christensen – Own work (CC BY-SA 4.0) via Commons Wikimedia