Adaptive Immunity

How would you describe adaptive immunity?

Specific, memory (primary and secondary immune responses), and uses lymphocytes

What are the major extracellular defense?

Antibodies

What’s recognized by antigens on the cell surfaces?

Internal pathogens and abnormal cells

What are abnormal and infected cells destroyed by?

Cell mediated immune response

What are antigens?

Antibody-generators, as well as any substance that reacts with an anti-body or T-cell receptor - they may produce an immune response

What are some examples of antigens?

Proteins, carbohydrates, the flu, E. coli

Where can antigens be found?

Free in blood/tissue, on pathogen surfaces, and on the surfaces of infected cells

How do you check an antigen?

Cells have a surface protein that shows antigens that are inside the cell

Human cells present what?

Their own antigens

What does MHC stand for?

Major histocompatibility complex

Describe MHC-I

Identifies “self,” and presents intracellular antigens on cell surface

Describe MHC-II

Antigen-presenting cells, include dendritic cells, macrophages, and B-cells - also show off phagocytosed antigens

What is the humoral immune response?

Defends against extracellular antigens, includes B-lymphocytes, plasma cells, and memory cells

What is the Fc region?

Constant region, determines type (class) of antibody

What is the Fab region?

Variable region, determines antigen specificity

What is the IgG antibody class?

Most common, can cross the placenta

What is the IgM antibody class?

First responder, pentamer

What is the IgE antibody class?

Allergic reactions, binds to mast cells, basophils

What is the IgA antibody class?

Secreted antibody, mucus, tears, saliva, breast milk

How do antibodies work?

Neutralized, aggluinate and precipitate, remote phagocytosis, activate the complement, and mark cells for destruction

What is B-cell diversity?

Each B-cell makes its own unique antibody, involved with gene splicing/rearrangement - only B-cells with the proper antibody respond to an infection

What are the humoral immune response steps?

Digestion of an APC

Free antigen binds to the B-cell

APC activates the T-cell

T-cell activates the B-cells

B-cell → antibodies and memory cells

What is class switching?

Promoted by helper T-cells

IgG → plasma and tissue

IgA → Mucus

What is a primary immune response?

First time the antigen is encountered, 1-2 weeks, low Ab levels

What is the secondary immune response?

Involved memory cells, rapid and bigger response, antigen-specific

Vaccination - what is active immunity?

Injection of killed, attenuated, or part of pathogen - generates antibody and memory

Vaccination - what is passive immunity?

Injection of antibody only, provides temporary protections

What are helper T- cells (CD-4 cells)

Interact with antigen presenting cells and release cytokines, activate B, T, NK, and macrophage cells and direct the immune response

What are cytotoxic T-cells (CD-8 cells)

Interact with any cell that has MHC-I

APC → Tc is activated by it

Tissue cell → Tc attacks it

What is cell-mediated immunity?

Defense against infected cells

How to cytotoxic T cells defend against infected cells?

Using t-lymphocytes, a CD8 receptor for MHC-I, recognition of infected cells

What to cytotoxic T cells release?

Performs and granzymes, can destruct the infected cell

What is the cell-mediated immune response?

Antigen is engulfed and processed (APC is activated by TLR)

Antigen is presented to T - cell (involves CD8 and MHC-1 + cytokines)

T cell is activated

Activated cell binds to abnormal host cells