Difference Between Cell Mediated and Antibody Mediated Immunity

The key difference between cell mediated and antibody mediated immunity is that cell mediated immunity destroys infectious particles via cell lysis by cytokines, without the production of antibodies, while antibody mediated immunity destroy pathogens by producing specific antibodies against antigens.

Cell mediated immunity and antibody mediated immunity are two types of primary defence mechanisms taking place in our body. Cell mediated immunity operates against intracellular pathogens. Hence, it works inside infected cells and destroys pathogens by releasing cytokines. In contrast, antibody mediated immunity operates against extracellular pathogens by producing antibodies against the antigens present outside the infected cells or free circulating in the blood. Moreover, B lymphocytes mainly carry out antibody mediated immunity while T lymphocytes carry out cell mediated immunity.

CONTENTS

1. Overview and Key Difference
2. What is Cell Mediated Immunity
3. What is Antibody Mediated Immunity
4. Similarities Between Cell Mediated and Antibody Mediated Immunity
5. Side by Side Comparison – Cell Mediated vs Antibody Mediated Immunity in Tabular Form
6. Summary

What is Cell Mediated Immunity?

Cell mediated immunity is a type of primary immune response operating in our body. Cell mediated immunity does not induce the production of antibodies. It occurs through the release of various cytokines and activation of phagocytes. Cell mediated immunity works against intracellular pathogens such as viruses and bacteria. Once a pathogen enters a cell and infects it, antibody mediated immunity cannot identify it. Hence, cell mediated immune response comes into play and kills the infected cell before the multiplication of pathogen inside the cells.

T lymphocytes are the major immune cells that carry out cell mediated immunity. Naïve T cells activate and convert into effector T cells after encountering antigen-presenting cells (APCs).  Helper T cells release cytokines that help activated T cells to bind to the infected cells’ MHC-antigen complex and differentiate the T cell into a cytotoxic T cell. Cytotoxic T cells then induce the infected cell to undergo apoptosis or cell lysis. Moreover, cytokines recruit natural killer cells and phagocytes to destroy infected cells. In this way, cell mediated immunity responds to viral infections, graft rejection, chronic inflammation and tumour immunity.

What is Antibody Mediated Immunity?

Antibody mediated immunity, as the name implies, occurs via the production of antibodies. It specifically responds to antigens that are freely circulating or present outside the infected cells. When an antigen enters into our serum with the help of helper T cells, B lymphocytes differentiate into plasma cells. Plasma cells proliferate, and all proliferated plasma cells produce specific antibodies against the antigens. Antibodies bind with antigens and neutralize or deactivate them or cause lysis.

Antibodies are immunoglobulin proteins. There are five types of antibodies as IgA, IgG, IgM, IgE and IgD. IgG is the most abundant type of antibody. Antibodies diminish after they deactivate antigens. However, B lymphocytes produce memory cells when they encounter an antigen. These memory cells produce plasma cells and antibodies rapidly and intensely when we are exposed to the same antigen the second time. Therefore, antibody mediated immunity provides long-lasting immunity for specific antigens.

What are the Similarities Between Cell Mediated and Antibody Mediated Immunity?

• Cell mediated and antibody mediated immunity are two categories of adaptive immunity.
• They are primary defence mechanisms.
• Helper T cells assist both types of immunity.
• Both types of immunity usually develop concurrently in vivo, and the two responses often act synergistically.

What is the Difference Between Cell Mediated and Antibody Mediated Immunity?

Cell mediated immunity is facilitated by T lymphocytes via the release of cytokines while antibody mediated immunity is facilitated by B lymphocytes via the production of antibodies. So, this is the key difference between cell mediated and antibody mediated immunity. Cell mediated immunity works against intracellular pathogens while antibody mediated immunity works against extracellular pathogens. Furthermore, cell mediated immunity creates a delayed response, while antibody mediated immunity creates a rapid response. This is also a difference between cell mediated and antibody mediated immunity.

The below infographic summarizes the difference between cell mediated and antibody mediated immunity.

Summary – Cell Mediated vs Antibody Mediated Immunity

Cell mediated immunity and antibody mediated immunity are two categories of the adaptive immune system. Antibody mediated immunity is the primary defence system that works against extracellular pathogens. It is mainly facilitated by B lymphocytes via antibody production. In contrast, cell mediated immunity is the primary defence system that works against intracellular pathogens. It is mainly facilitated by the T lymphocytes via cytokine release. Helper T cells assist both cell mediated, and antibody mediated immunity. Therefore, this is the brief description of the difference between cell mediated and antibody mediated immunity.

Reference:

1. Janeway, Charles A, and Jr. “T Cell-Mediated Immunity.” Immunobiology: The Immune System in Health and Disease. 5th Edition., U.S. National Library of Medicine, 1 Jan. 1970, Available here.
2. “Humoral Immunity.” Wikipedia, Wikimedia Foundation, 7 Sept. 2019, Available here.

Image Courtesy:

1. “T cell activation” By T_cell_activation.png: Template drawing and caption text from “The Immune System”, (Public Domain) via Commons Wikimedia
2. “B cell activation” By Fred the Oysteri (Public Domain) via Commons Wikimedia