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Antibody Structure

Antibody Structure

Overview
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...

Antibody Structure and Classes

Antibody Structure and Classes

Antibodies, also known as immunoglobulins, are produced by B cells in response to foreign substances, such as bacteria and viruses. These proteins are critical for recognizing and neutralizing these substances, protecting the body from potential harm.
The basic structure of an antibody consists of four protein chains: two identical heavy chains and two identical light chains. These chains are held together by disulfide bonds and other non-covalent interactions, forming a Y-shaped structure.

Antibody Actions

Antibody Actions

Antibodies, or immunoglobulins, are critical players in the immune system's arsenal against invading pathogens. Produced by B cells and plasma cells, their primary role is to detect and bind to specific antigens, molecules found on the surface of pathogens like bacteria or viruses. Beyond antigen recognition, antibodies perform several vital functions that contribute to immune defense.
Neutralization
Antibodies can bind to pathogens, preventing them from infecting host cells. This process...

Development of Immunocompetence

Development of Immunocompetence

The initiation of cell-mediated immunity can be observed as early as the third month of fetal growth, with active antibody-mediated immunity following approximately one month later.
The initial cells that migrate from the fetal thymus settle within the skin and epithelial tissues lining the mouth, digestive tract, and in females, the uterus and vagina. These cells, including skin-based dendritic cells, serve as antigen-presenting cells, playing a key role in T cell activation.
Subsequent T...

Transcytosis of IgG

Transcytosis of IgG

Transcytosis is the process in which molecules are internalized by endocytosis, transported across the cell, and released through exocytosis from the opposite end of the cell. Molecules such as insulin, immunoglobulins, and certain nutrients are transferred through the recycling endosomes by recycling and transcytosis.
IgG molecules from a mother undergo transcytosis starting around 13 weeks of gestation. The amount of IgG transferred and entering the fetal blood circulation increases with...

B Cell Activation and Differentiation

B Cell Activation and Differentiation

The adaptive immune response, a sophisticated defense mechanism, relies on the activation and differentiation of B lymphocytes, or B cells. These processes enable our bodies to mount a tailored response against specific pathogens such as bacteria, free virus particles, toxins, and parasites.
When naive B cells encounter a specific antigen that can bind to the B cell receptor (BCR) on their surface, they undergo sensitization to respond to the antigen's presence. Sensitization begins with...

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Related Experiment Video

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Murine Nasal Lavage Fluid Collection without Blood Contamination

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Production and Function of Immunoglobulin A.

Timothy W Hand¹, Andrea Reboldi²

¹R.K. Mellon Institute for Pediatric Research, Department of Pediatrics, Division of Infectious Diseases, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pennsylvania 15224, USA;

Annual Review of Immunology

|March 1, 2021

Summary

Immunoglobulin A (IgA) antibodies protect mucosal surfaces but have limited immune cell activation. IgA

Keywords:

Peyer's patch germinal center immunoglobulin A microbiota mucosal immunology transforming growth factor beta

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Characterization of Thymus-dependent and Thymus-independent Immunoglobulin Isotype Responses in Mice Using Enzyme-linked Immunosorbent Assay

Characterization of Thymus-dependent and Thymus-independent Immunoglobulin Isotype Responses in Mice Using Enzyme-linked Immunosorbent Assay

Published on: September 7, 2018

Area of Science:

Immunology
Microbiology
Molecular Biology

Background:

Immunoglobulin A (IgA) is a unique antibody class secreted onto mucosal surfaces.
Its structure aids survival in harsh mucosal environments but limits immune cell effector functions.
Despite limitations, IgA is crucial for preventing infections and shaping the gut microbiome.

Purpose of the Study:

To explore the unique functional characteristics and antigen-binding repertoire of IgA.
To understand how IgA regulates intestinal bacteria and interacts with the gut environment.

Main Methods:

Analysis of IgA structure and its interaction with secretory components.
Characterization of the IgA antigen-binding repertoire, including polyspecificity and cross-reactivity.
Investigation of the role of gut-associated lymphoid tissue (GALT) in IgA development.

Main Results:

IgA's structure facilitates mucosal survival but restricts effector functions.
IgA exhibits a diverse antigen-binding repertoire, essential for regulating intestinal bacteria.
Local cues from GALT and the intestinal environment shape IgA function and specificity.

Conclusions:

IgA plays a vital role in mucosal immunity and microbiome homeostasis.
The distinct properties of IgA are shaped by its unique structure and the gut environment.
Understanding IgA's function is key to developing strategies against mucosal infections.