Lecture 11 Flashcards
(25 cards)
What is adaptive immunity?
Highly specific defense mechanism of the immune system that develops after exposure to pathogens or foreign substances
What are the key features of adaptive immunity
Specificity
- Targets specific antigens through precise molecular recognition
Memory:
- Develops immunological memory, enabling faster and stronger responses to repeat exposures
Diversity:
- Recognises an enormous variety of antigens
Self vs. non-self recognition:
- differentiated between the body’s own cells and foreign invaders to prevent autoimmune response
What are the types of adaptive immunity?
Active immunity:
- Acquired through infection or vaccination = long-term protection
Passive immunity:
- Acquired through the transfer of antibodies, such as maternal antibodies to a newborn = temporary protection
What is cell mediated immunity?
- Mediated by T lymphocytes which directly attack infected or abnormal cells
- Targets intracellular pathogens and abnormal cells
What is humoral immunity?
- Mediated by B lymphocytes and involve the production of antibodies that circulate in bodily fluids
- Targets extracellular pathogens
Development of B and T cells
What are the key mechanisms of Humoral Immunity?
Antigen Recognition:
- B cells recognise specific antigens via surface receptors
Activation of B cells:
- Upon antigen binding, they activated
Antibody Production:
- Activated B cells differentiate into plasma cells, secreting antibodies
Memory B Cells:
- Long term immunity by responding rapidly to future exposures to same antigen
What is an antibody?
Protein produced by adaptive immune system in response to presence of antigen
- aka immunoglobulin
What cells produce antibodies?
Plasma cells
What is the structure of an antibody?
- Y shaped glycoproteins
- 2 heavy chains and 2 light chains
- 2 light chains are made up of 2 domains and heavy is made of 4
- Heavy chains connected by covalent disulfide bridges
What does IgM do?
First responder during an infection
What does IgD do?
Primarily a B cell receptor and has a more limited role compared to other immunoglobulins
What does IgG do?
is the most abundant and versatile antibody, critical for long-term immunity
What does IgA do?
Protects mucosal surfaces and is a key player in passive immunity to newborns
What does IgE do?
Essential for defense against parasitic infection and is involved in allergic reactions
Primary and secondary humoral responses
The primary response to antigen A generates memory cells that give rise to the enhanced secondary response to antigen A
What are the key mechanisms in cell mediated immunity?
Antigen Presentation:
- APCs display antigens on their surface using MHC molecules to activate T cells
Activation of T Cells:
- Cytotoxic = destroy by inducing apoptosis
- Helper T cells = coordinate the immune response by releasing cytokines
Memory T Cells:
- Provide long lasting immunity
What are the two major populations of T cells?
CD4 and CD8 T cells.
What do CD4 T cells usually differentiate into?
Helper T (TH) cells.
What is the main role of helper T (TH) cells?
They activate B cells, other T cells, and macrophages, and direct the adaptive immune response.
What is another type of CD4 T cell besides helper T cells?
Regulatory T (Treg) cells.
What is the function of regulatory T (Treg) cells?
They moderate (suppress) the immune response.
What do CD8 T cells differentiate into?
Cytotoxic T (TC) cells.
What is the role of cytotoxic T (TC) cells?
They destroy infected or foreign cells in the body.
