immune 2 Flashcards
Lymphocytes characteristics
WBC capable of recognizing antigens. they have antigen receptors on cell membranes
T lymphocytes can recognize different parts of the antigen
How do receptor proteins work
They are shaped to bind to a specific antigen. Antigens can be remembered by the body using special cells
Antigen characteristics
usually a protein. They have an epitope/antigenic determinant where a receptor reacts to a small piece of protein
epitope
antigenic determinant
MHC
major histocompatibility complex
membrane proteins that mark cells as part of the body
MHC 1 found
all body cells except RBC
MHC 2 found
on cells that can act as antigen presenting cells
APC
antigen presenting cell
can be dendritic, macrophages or B lymphocytes
Cytokines
Small proteins that help controle immune response secreted by APCs, macrophages or mast cells
help attract WBC
help stimulate phagocytosis and clonal expansion of T and B cells
Cytokine types
perforin
prostaglandin
tumor necrosis factor
interferon
histamines
interleukins
pyrogens
of antigen receptors in the body
100 million. made of different parts of genes
B cells are called this because
they are made in the red Bone marrow
B cell purpose
respond to antigens
produce plasma cells to make antibodies and memory b cells
T cells are called this because
they mature in the Thymus but are made in the red bone marrow
Types of T cells
cytotoxic: kill infected cells
memory: remembers antigen and can respond
helper: regulates immune response by releasing cytokines
T cell clonal expansion
- Macrophage with MHC II proteins encounters an antigen (Ag)
- macrophage engulfs antigen and present antigenic epitope on MHCII protein becomes APC
- APC encounters immature T cell with receptor II +CD4
- APC secretes IL1+ CD4 T cell autocrine secretes and binds to ILII
- colonal expansion makes helper t+memory T cells. Happens in tonsils, lymphnodes and other lymphatic tissues and organs
Costimulation
when APC binds to Th at the antigen and IL1 and IL2 are secreted
Cytotoxic T cell expansion
- antigen (Ag) encounters and binds MHC1 immature cytotoxic T cell receptor with CD8 protein
- Costimulation done with helper T cell secreting IL2 to the cytotoxic t cell.
- clonal expansion makes more Tc and memory Tc. Tc goes through blood stream to find and kill infected cells by releasing perforin and can release lymphotoxin or granzymes to induce cell death, can induce tumor necrosis factor and can cause cytolysis
Tc cells are trained in the thymus not to hurt self cells
B cells can circulate in
blood and lymph
Antibodies (Ab)
known as immunoglobulin (Ig) secreted by Bcell receptors
have 2 heavy chains and 2 light chains of poly peptides (quaternary structure)
Functions of antibodies
5 catagories
1. neutralize: binds to antigen prevents body from attaching to body cells/toxins
2. immobilize bacteria: binds to flagella on bacteria
3. clumping: agglutination clumping of body cells. precipitation: clumping of molecules/toxins/proteins causes it to precipitate out of solution
4. activate complement system:
5. stimulate phagocytosis: makes antibodies for destruction
Ig types (immunoglobulin)
- IGG: Y shape 80% of antibodies in the blood, can be in lymph can cross placenta to share immunity with fetus. can activate complement sys. enhance phagocytosis
- IGM: Pentomer: 5-10%. largest: stimulates macrophages early in infection. activates complement system, clumps, peaks before IGG
- IGA: Dimer: 10% Ig. what we secrete, mucous, tears, milk. prevents binding to epithelial cells or entering bloodstream. keep out of body
- IGD. monomer. forms B cell receptors on immature B cells says ready for activation
- IGE: monomer on dendritic cells mostly in tissues. stimulates histamine release->inflammation. protect from parasitic worms
Second exposure there s an increase in
IGG/Y immunoglobulin
Passive induced immunity
patient is given antibodies for infection works until Antibodies run out: anti venom
Active induced
memory T+B cells made by the body: vaccines: long term resistance
B cell clonal expansion
- B cell with MHCII and Bcell receptors )BcR)
- encounter Ag and B cell becomes APC on MHCII of B cell
- Encounters a helper tcell: CD4 cell releases ILII->stimulates B cell colonal expansion
- Makes plasma cells and some B cells
- plasma cells secrete antibodies
