Researchers have discovered new information about how the body’s immune system works. At the same time, it has challenged decades of understanding of the process of antibody-mediated immunity and opened the door to advances in immunological therapy.
B cells, a type of white blood cell, drive the body’s antibody-mediated immunity by creating antibodies that bind to and neutralize pathogens and foreign substances. B cells also produce harmful antibodies that attack normal tissues, causing allergic reactions and autoimmune diseases.
Antibodies are made in response to markers called antigens that tell the immune system that a foreign substance (bacteria, virus, or vaccination) is present in the body. Antibodies recognize and attack harmful antigens, but they are specific. Antibodies are like keys, antigens are like keys. Antibodies only unlock specific antigens.
Embedded on the surface of B cells is the B cell receptor (BCR). B-cell receptors (BCRs) are defense proteins ready to bind antigens. For decades, scientists and researchers have believed that antigens cross-link several BCRs, group signaling molecules, transmit signals to cells, and attract help from T cells to destroy invaders. I was thinking
The figure below shows two antigens (light blue spheres) bound to clusters of BCR (purple Y-shaped structures) on the cell surface. Dark blue and black shapes represent signaling molecules (lightning bolts) that transmit signals to cells.
Seiren Egedal Degun
But researchers at Denmark’s Aarhus University, in collaboration with the Max Planck Institute in Munich, have overturned years of scientific consensus with a new study of the molecular mechanisms underpinning B-cell activation.
Their study sought to answer two questions. First, how is the BCR distributed when cells are quiescent? Second, what are the minimal requirements for antigen-driven activation of the BCR?
To answer the first question, researchers used DNA-based point deposition for imaging nanoscale topography (DNA-PAINT). This super-resolution method allows visualization of single molecules of nucleic acid nanostructures with a resolution of approximately 5–10 nanometers. They found that when cells were quiescent, the BCR was not clustered in an organized manner, as previously thought.
To address the second question, researchers looked at the exact ratio of antigen to BCR. Finding no qualitative difference between activation by a single antigen and activation by multiple antigens, they concluded that a single antigen could activate her B cells.
The results of this study are presented below. A single spaced apart BCR interacts with an antigen (here a light blue hexagon) to elicit the same signaling response within the cell.
Seiren Egedal Degun
“We showed that the way B cell activation has been described over the past 30 or 40 years is wrong,” said Associate Professor Søren Degn, the corresponding author of the study. “This is an important discovery because it opens the door to better vaccines and better treatments for many diseases.”
Uncovering the biological processes underlying the body’s B cell-mediated immune response is an important discovery with potentially far-reaching implications.
“This result is important because it represents a breakthrough in our understanding of how these critical immune cells ‘see’ their enemies,” said Degn. “If we understand how B cells are activated, we can create better vaccines. not.”
The study was published in a journal Nature Communications.
Source: Aarhus University
