B Cells vs T Cells | B Lymphocytes vs T Lymphocytes - Adaptive Immunity - Mechanism

Summary

This video explains the roles of B cells and T cells in the immune system, highlighting their shared origin from hematopoietic stem cells in the bone marrow. B cells are responsible for recognizing antigens and producing antibodies, while T cells, including helper T cells and cytotoxic T cells, target and eliminate infected cells. The video also covers the function of memory T cells in quickly responding to previously encountered antigens. Together, B and T cells form a crucial part of the adaptive immune system, specifically fighting infections and protecting the body.

Takeaways

• 😀 B cells and T cells are both white blood cells that play crucial roles in the immune system, specifically in fighting infections.
• 😀 Both B and T cells originate from hematopoietic stem cells in the bone marrow through differentiation processes.
• 😀 B cells primarily function in recognizing antigens, which are molecules found on the surface of pathogens or foreign substances.
• 😀 B cells are equipped with B cell receptors that bind to antigens, allowing them to initiate an immune response.
• 😀 Once a B cell binds an antigen, the antigen is engulfed through receptor-mediated endocytosis and processed for presentation on the B cell surface.
• 😀 The antigen-presenting B cell activates helper T cells (CD4 cells) through the major histocompatibility complex (MHC) class II molecules.
• 😀 Activated helper T cells release lymphokines that trigger B cell cloning and differentiation into plasma cells, which produce antibodies.
• 😀 Antibodies produced by plasma cells are highly specific to the initial antigen encountered by the B cell.
• 😀 T cells include helper T cells (CD4) and cytotoxic T cells (CD8), with distinct roles in the immune response.
• 😀 Cytotoxic T cells recognize infected cells presenting viral proteins on MHC class I molecules, binding to them and initiating cell death (apoptosis).
• 😀 Memory T cells rapidly replicate and respond quickly if they encounter the same antigen again, contributing to faster immune reactions.
• 😀 Both B and T cells are integral to the body's adaptive immunity, offering specialized and targeted responses to pathogens.

Q & A

What are B cells and T cells?

B cells and T cells are types of white blood cells that play vital roles in the immune system by defending the body against infections. B cells mainly produce antibodies, while T cells assist in recognizing and killing infected cells.

Where do B and T cells originate from?

B and T cells both originate from the hematopoietic stem cell in the bone marrow. These stem cells differentiate into B cells and T cells.

What is the function of B cells in the immune system?

B cells primarily recognize and bind to foreign molecules called antigens. Once they bind to an antigen, B cells activate and produce antibodies specific to that antigen to help fight infections.

How do B cells interact with antigens?

B cells have receptors called B cell receptors on their surface that bind to antigens. After binding, the antigen is engulfed by the B cell and processed. The processed antigen is then presented on the surface of the B cell for further immune interactions.

What is the role of helper T cells (CD4) in the immune response?

Helper T cells (CD4) interact with B cells by binding to the antigen-MHC class II complex on B cells. This binding triggers the release of lymphokines that help activate B cells, causing them to clone and differentiate into plasma cells that produce antibodies.

What is MHC class II and its role in immune function?

MHC class II is a molecule on the surface of B cells that presents processed antigens to helper T cells. This interaction helps activate the immune response by signaling T cells to release lymphokines, which further stimulate the immune process.

What are plasma cells and their function?

Plasma cells are the differentiated form of B cells. Their main function is to produce and release large quantities of antibodies specific to the antigen that originally activated the B cell.

How do cytotoxic T cells (CD8) respond to infected cells?

Cytotoxic T cells (CD8) target infected cells by recognizing foreign viral proteins displayed on the infected cell’s surface via MHC class I. After binding, cytotoxic T cells initiate apoptosis (programmed cell death) to eliminate the infected cell.

What is apoptosis, and how do cytotoxic T cells induce it?

Apoptosis is a process of programmed cell death. Cytotoxic T cells induce apoptosis by releasing cytotoxins like perforin or granulysin or by binding to the Fas molecule on the infected cell, forming a death-inducing signaling complex that triggers cell death.

What are memory T cells, and how do they function?

Memory T cells are a subset of T cells that 'remember' previous encounters with pathogens. They are capable of replicating rapidly and responding quickly if the same antigen is encountered again, providing faster and more efficient immune protection.