Related Experiment Video

Updated: Aug 8, 2026

Measuring TCR-pMHC Binding In Situ using a FRET-based Microscopy Assay
19:05

Measuring TCR-pMHC Binding In Situ using a FRET-based Microscopy Assay

Published on: October 30, 2015

Major histocompatibility complex class I-dependent cell binding to isolated Ly-49A: evidence for high-avidity

C S Chang1, L Shen, D E Gong

  • 1Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada.

European Journal of Immunology
|December 1, 1996
PubMed

Insights

Ly-49A molecules regulate natural killer (NK) cell activity by binding to H-2Dd. Low Ly-49A density on NK cells creates a threshold, impacting target cell lysis and NK cell function.

Area of Science:

  • Immunology
  • Cellular Biology
  • Molecular Interactions

Background:

  • Ly-49A receptors on mouse natural killer (NK) cells inhibit the lysis of target cells expressing H-2Dd.
  • Understanding the molecular mechanisms of Ly-49A-mediated inhibition is crucial for NK cell function regulation.

Purpose of the Study:

  • To investigate the role of Ly-49A density in mediating cell adhesion to H-2Dd-expressing target cells.
  • To determine the threshold density of Ly-49A required for stable receptor engagement and its impact on NK cell function.

Main Methods:

  • Immunoaffinity purification of Ly-49A from EL4 lymphoma using the A1 monoclonal antibody (mAb).
  • Assessment of cell adhesion to immobilized Ly-49A by cells expressing varying levels of H-2Dd.
  • Enzyme-linked immunosorbent assay (ELISA) to confirm Ly-49A density and antibody inhibition studies.

Main Results:

  • Cell adhesion to Ly-49A was observed in cells with high H-2Dd expression, inhibited by anti-Dd or anti-Ly-49A antibodies.
  • A threshold density of Ly-49A (140-250 molecules/µm²) was required for cell adhesion, with increased density enhancing binding.
  • High avidity of Ly-49A for Dd was demonstrated, with small density changes near the threshold causing significant alterations in receptor engagement.

Conclusions:

  • Ly-49A density critically influences NK cell adhesion and function, explaining how minor expression differences affect target cell lysis.
  • The findings highlight the importance of Ly-49A density-dependent interactions in NK cell-mediated immune responses.

More Related Videos

Use of Single Chain MHC Technology to Investigate Co-agonism in Human CD8+ T Cell Activation12:09

Use of Single Chain MHC Technology to Investigate Co-agonism in Human CD8+ T Cell Activation

Published on: February 28, 2019

Immunopeptidomics: Isolation of Mouse and Human MHC Class I- and II-Associated Peptides for Mass Spectrometry Analysis09:32

Immunopeptidomics: Isolation of Mouse and Human MHC Class I- and II-Associated Peptides for Mass Spectrometry Analysis

Published on: October 15, 2021

Related Concept Videos

Affinity and Avidity01:41

Affinity and Avidity

Overview
Cell Adhesion Molecules - Types and Functions01:20

Cell Adhesion Molecules - Types and Functions

Cell adhesion molecules (CAMs) are pivotal to multicellularity and the coordinated functioning of tissues and organ systems. They enable physical interactions between cells and provide mechanical strength to tissues. They also function as receptors for signal transmission across the plasma membrane. The CAMs are broadly classified into four families - integrins, cadherins, selectins, and immunoglobulin-like CAMs (IgCAMs).
CAM Families
The Integrin family of proteins is primarily  involved in a...
Selectins01:25

Selectins

Cell adhesion is  an essential aspect of multicellularity. While stable cell interactions usually occur between cells of the same type, transient cell interactions occur between cells of different tissue types, such as between neutrophils and endothelial cells. Selectins are one class of cell adhesion molecules (CAMs) that bind carbohydrate ligands to form transient cell adhesion. They are rod-like proteins with a long extracellular part of variable length ending with the lectin domain, which...
Immunoglobulin-like Cell Adhesion Molecules01:31

Immunoglobulin-like Cell Adhesion Molecules

Immunoglobulin-like cell adhesion molecules or Ig-CAMs are a versatile group of cell surface glycoproteins belonging to the immunoglobulin protein superfamily. Ig-CAMs possess the characteristic immunoglobulin protein domains and other domains such as the fibronectin type III domain. The Ig domains are glycosylated to varying degrees in different Ig-CAMs.
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...
Antigens Involved in Adaptive Immunity01:26

Antigens Involved in Adaptive Immunity

An antigen is any substance the immune system identifies as foreign and potentially harmful to the body, prompting an immune response. Antigens have two functional properties: immunogenicity and reactivity. Immunogenicity is the ability of an antigen to stimulate a specific immune response. At the same time, reactivity describes the antigen's ability to react with the cells and antibodies produced in response to it.
Complete Antigens
Complete antigens possess both immunogenicity and reactivity.
T Cell Activation and Clonal Selection01:22

T Cell Activation and Clonal Selection

T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
Naive T cells that have not yet encountered an antigen express two primary CD...