What is the Difference Between PAMPs and Antigens

The immune system is extremely important for the defence against pathogens. PAMPs and antigens are major structures in the activation of the immune system. They can be recognized by the host’s immune system, thus triggering the immune response.

The key difference between PAMPs and antigens is their nature. PAMPs are molecular motifs found on numerous pathogens but not present in the host, while antigens are proteins that act as markers and are unique to a specific pathogen.

CONTENTS

1. Overview and Key Difference
2. What are PAMPs  
3. What are Antigens
4. Similarities – PAMPs and Antigens
5. PAMPs vs Antigens in Tabular Form
6. Summary – PAMPs vs Antigens
7. FAQ – PAMPs and Antigens

What are PAMPs?

PAMPs are known as pathogen-associated molecular patterns. They are small molecular motifs conserved within a class of microbes or pathogens. PAMPs can be recognized by toll-like receptors (TLRs) and other pattern recognition (PRRs) in both plants and animals. This mechanism helps the innate immune system to recognize the respective pathogens.

A vast array of different types of molecules can serve as PAMPs, such as glycans, glycoconjugates (viral glycoproteins in a viral envelope), flagellin, dsRNA, CpG motif, and fungal PAMPS on the cell surface. Viral glycoproteins and fungal PAMPS on the cell surface are recognized by TLR2 and TLR4 receptors in the host. Flagellin is recognized by TLR5 in the host. Furthermore, nucleic acid variants, such as dsRNA, are recognized by TLR3, and unmethylated CpG motifs are recognized by TLR9 in the host.

What are Antigens?

Antigens are markers, proteins, or strings of amino acids that the immune system can recognize. Normally, activation of the adaptive immune defences is triggered by pathogen-specific molecular structures called antigens. Antigens are usually proteins or sugars such as polysaccharides found on the outside of things like cells or viruses. Antigens exist in viruses, bacteria, allergens, parasites, proteins, tumor cells, and normal cells in the body. Antigens in the normal body cells are known as self, while antigens in the pathogens are known as non-self.

Antigen-presenting cells help the immune system to recognize them. There are three types of antigen-presenting cells in the body: macrophages, dendritic cells and B cells. Then, the body defends itself against harmful antigens with antibodies. Furthermore, these antibodies are produced in the body with the help of cells known as B cells.

Similarities Between PAMPs and Antigens

1. PAMPs and antigens are very important structures in the activation of the immune system.
2. They can be recognized by the host’s immune system, triggering the immune response.
3. Both are identified by certain receptors or cells in the body.
4. They are extremely important for the defence and the survival of plants and animals.

Difference Between PAMPs and Antigens

Definition

1. PAMPs are small molecular motifs conserved within a class of microbes or pathogens.
2. Antigens are markers that tell the body that something is foreign.

Nature

1. PAMPs include molecules such as glycans, glycoconjugates (like viral glycoproteins found in viral envelopes), flagellin, double-stranded RNA (dsRNA), CpG motifs, and fungal PAMPs on the cell surface.
2. Antigens are often composed of proteins or sugars, such as polysaccharides.

Type of Immune System

1. PAMPs help to trigger the innate immune system.
2. Antigens help to trigger the adaptive immune system.

Recognized by

1. PAMPs such as viral glycoproteins and fungal PAMPs on the cell surface are recognized by Toll-like receptors (TLR2 and TLR4) in the host. Flagellin is recognized by TLR5 in the host, nucleic acid variants like dsRNA are recognized by TLR3, and unmethylated CpG motifs are recognized by TLR9 in the host.
2. Antigens are recognized by specialized immune cells such as macrophages, dendritic cells, and B cells, which play a key role in orchestrating an immune response.

The following table summarizes the difference between PAMPs and antigens.

Summary – PAMPs vs Antigens

PAMPs and antigens are very important structures in the immune system. PAMPs are molecular motifs found on numerous pathogens but not present in the host while antigens are proteins that act as markers which are unique to a specific pathogen. Furthermore, PAMPs help to trigger the innate immune system whereas antigens help to trigger the adaptive immune system. This summarizes the difference between PAMPs and antigens.

FAQ: PAMPs and Antigens

1. What are PAMPs in the immune system?

• Pathogen-associated molecular pattern molecules (PAMPs) are derived from microorganisms or pathogens. They are molecular motifs of pathogens and are recognized by pattern recognition receptor (PRR) bearing cells of the innate immune system and many epithelial cells.

2. What are the differences between pathogens and antigens?

• Pathogens are microbes that can infect the human body and ultimately cause illness. Antigens are parts of the pathogen that trigger the human body to an infection caused by the pathogen. Immune cells can recognize these antigens to target and remove a pathogen from the body.

3. What is the function of the antigen?

• An antigen is any substance that triggers the immune system to produce antibodies against it. An antigen may be a substance from the environment, such as chemicals, bacteria, viruses, or pollen.

4. What are the main types of antigens?

• There are several types of antigens categorized based on where they come from. These types include exogenous antigens, endogenous antigens, autoantigens, and tumor antigens.

5. Is antigen good or bad?

• Antigens are very important to human body and the immunity of people. They play a crucial role in the prevention and elimination of diseases by triggering the immune system, helping it to prevent the infections caused by pathogens. Therefore, we can describe antigens as ‘good.’

Reference:

1. Parker, Nina, et al. “18.1 Overview of Specific Adaptive Immunity – Microbiology.” OpenStax.
2. “Antigen: What It Is, Function, Types, & Testing.” Cleveland Clinic.

Image Courtesy:

1. “PAMPs and PRRs in the Innate Immune System” By Immcarle105 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Antigens presentation“By pl.wiki: Masurcommons: Masurirc: [1] – Own work (CC BY 2.5) via Commons Wikimedia