Week 7 - Cells involved in the adaptive immune system Flashcards
(14 cards)
What are T helper cells (CD4+)
Don’t directly kill pathogens but coordinate the immune response by releasing cytokines.
- has CD4+
Function
- recognise antigens presented by APCs on MHC class 2 molecules
- once antivated they release cytokines (mainly IL-2)
these cytokines help:
- activate B cells to produce antibodies (humoral immunity)
- Activate cytotoxic T cells to kill infected cells (cell mediated immunity)
What are cytotoxic T cells (CD8)
Directly kill infected or cancerous cells
Function
- recognise infected or abnormal cells by binding to antigens presented on MHC Class 1 molecules
- once activated (with help from helper T cells) they release toxic substances which cause cell death
What are B cells (B lymphocytes)
- develop and mature in bone marrow
function
- when B cell binds to its specific antigen it can be activated by signals from helper T cells
- once activated B cells transform into plasma cells that produce antibodies which neutralise pathogens
- or turns into memory cells
Plasma cells
when B cells are activated by helper T cells and encounter an antigen they differentiate into plasma cells, which secrete large amounts of antibodies specific to the pathogen
What are memory B cells
B cells which remember previous infections
What are Regulatory T cell (Tregs)
Type of immune cell which prevents excessive or harmful immune responses
Function
- prevent autoimmune responses by suppressing immune responses the activity of other immune cells (helper t cells, cytotoxic t cells, b cells ect), ensuring that the immune system doesn’t attack the body’s own tissue
Memory T cells
After your immune system has responded to a specific pathogen some T cells become memory T cells which remembers that pathogen so the immune system can respond faster and stronger if it invades again.
What are antigen presenting cells (APCs)
either a dendritic cell, macrophage or B cell which:
- engulf pathogens breaking them down
- using MHC class 2 molecules to display the fragments on the surface to present to T helper cells
What is FoxP3+
A key protein that distinguishes Tregs (T regulatory cells) from other T helper cells
Transcription facto r
FoxP3+ cells suppress the activity of other immune cells, preventing them from overreacting and causing inflammation or autoimmune diseases
- produced by T cells
Where do B and T cells originate
bone marrow
Where do B cells mature
Bone marrow
Where do T cells mature
thymus
what cell protein is on the surface of helper T cells
CD4+
what cell protein is on the surface of cytotoxic T cells
CD8+
