Cells Of The Immune System Flashcards
What are phagocytes?
monocytes
macrophages
neutrophils
B-cells
What are the adaptive system cells
T cells
- Helper
- Cytotoxic
B cells
- Naive
- Plasma
What are the professional APC cells?
B cells
Dendritic cells
Macrophages
What are the non-professional APC cells?
- Epithelial cells
2. Keratocytes
What are the receptors on T cells that accept signal from APC’s ?
- CD 40
2. CD 28
What are the types of molecules on the surface of the APC cells?
- Class I MHC —> non-professional APCs
2. Class II MHC —> professional APCs
What is the hematopoietic cell?
self-renewing cells that can differentiate into other cell types (pluripotent/multipotent) by a process called hematopoiesis.
What are the cells produced by hematopoietic cells?
- Myeloid
2. Lymphoid
What are the agranulocytes?
Monocytes ( macrophages )
T cells
B cells
What are the granulocytes?
Neutrophils
Eosinophils
Basophils ( mast cells ) —>largest granulocyte
NK-cells
What is characteristics of A. Eosinophil B. Neutrophils C. Basophils D. Monocytes E. Lymphocyte
A. Bilobed / acid-loving / bright red or pink
B. 3-6 lobes ( polymorphnuclear cells ) / most abundant / if the Pt has many neutrophils —> need antibiotic —> if still high then it is viral
C. Highly basic / highly granular
D. Kidney shaped nucleus / largest WBC in blood / in tissues —> macrophages —> APC
E. T and B cells
What happens when monocytes diff to macrophages.
- ⬆️ cell size
- ⬆️ no. And complexity of organelles
- ⬆️ phagocytes ability
R. ⬆️ Levels of hydrolytic enzymes and soluble factors
What are the funds of monocytes?
- phagocytosis (macrophages)
- antigen presentation
- cytokine production
What is the main activator of macrophages?
IFN Gama sec by Th-1 cell
What are the funds of neutrophils?
- phagocytosis
- oxygen dependent cytotoxicity
- non-oxygen-dependent cytotoxicity
- neutrophil extracellular traps (NETs).
What is the non oxidative cytotoxicity granules ?
- Myeloperoxidase
- bactericidal/permeability increasing protein (BPI)
- defensins
- serine proteases neutrophil elastase
- cathepsin G
- Alkaline phosphatase
- lysozyme
- NADPH oxidase
- collagenase
- lactoferrin
- histaminase
- cathelicidin
- Cathepsin
- gelatinase
- collagenase
What happens in the oxygen dependent cytotoxicity ?
Gives free radicals so it kills the microbe and cause tissue injury ( fights the protection but makes damage )
NADPH oxidase is inactive and unfunctional until there is a ligand that’s activated it by bringing all its parts together
Glutathione is a reducing agent that opposes the effect of it
What are the free radicals produced by oxygen cytotoxicity
- H2O2
- Hydrochloride acid
- Hydroxyl
What is the web of NET composed of ?
Chromatin and serine protease
What happens to the bacteria trapped in NET?
Killed by oxidative or non-oxidative mechanisms
What are the types of cell killing?
- Autophagy
- Apoptosis
- Necrosis
- Netosis
What is the function of eosinophils?
- play a major role in response to infection with multicellular parasites.
- Along with mast cells and basophils, they also control mechanisms associated with allergy and asthma (Th-2 mediated immune response).
مشتركة مع اللي بعدها في انها ليها دور في الحساسية و مشتركة مع اللي قبلها في انها phagocyte
What does the small granules of eosinophils contain?
- Chemical mediators e.g. histamines
2. Proteins e.g. A. eosinophil peroxidase B. RNase C. DNase D. lipase E. plasminogen, F. major basic protein
What is the function of basophils?
- First non-phagocytes cell
2. Play a role in acute and chronic allergic diseases (Th2- immune response), including: A. anaphylaxis B. asthma C. atopic dermatitis D. hay fever
- production of mediators e.g.
A. histamine
B. serotonin
C. heparin
What is special about mast cells?
Not in the blood only in tissues
What is the function of basophils ?
- secrete large amounts of histamine
2. plays a role in allergic reactions.
What does DC!s have?
- Class II MHC
2. co-stimulatory molecules
What are the characteristics of follicular DC’s
- 🚫 class II MHC
- In lymph follicles ( rich in B cells )
- Express ⬆️ levels of mem receptors for antibodies, needed for B cell responses
- 🚫 arise from BM
What are naïve lymphocytes?
cell that have not previously been stimulated by antigens, are at rest
What is clinal expansion
increased size and number of antigen-specific clone.
What is special about NK cells?
Called “natural killers” because they do not require activation to kill cells that are missing “self” markers of MHC class I.
• Harmful cells (virus or tumor infected) that are missing MHC class I markers cannot be detected and destroyed by T-cells.
Note: T helper and cytotoxic need signal from class II MHC ( helper ) or classI ( cytotoxic ) but NK cells don’t need stimulation from class I or Class II
What are the funcs of NK?
- Cell lysis bcz it has perforin and granzymes ( protease )
- ADCC bcz it has CD16 which is a mem receptor for the carbonyl-terminal end ( the Fc region ) of the IgG molecules that detects the infected cells optimized by antibodies
- Kills the infected cell which removed the class I MHC molecules
What are perforins?
forms pores in the cell membrane of the target cell —> create an aqueous channel through which the granzymes and associated
molecules enter —> induce either apoptosis or osmotic cell lysis.
What are the cells that secretes interferon Gama?
NKT cells and it activates macrophages
What are the molecules on the surface of B cells ?
- Ig receptor ( Fc receptors )
- B220
- Class II MHC
- Complement receptor: CR1 and CR2 ( they are the main activators of the comp system )
What is the function of TCR ?
Recognize antigens that are bound to MHC molecules
UNLIKE B cells which recognize the antigens freely
What is the marker on T suppressor ?
FOXP3
What is the function of T cytotoxic
- secrete few cytokines
2. mainly recognize and eliminate altered self-cells and some pathogens.
What are the keratinocytes?
Secrete various cytokines to induce a local inflammatory response and may act as non-professional APCs.
What are the langerhans cells?
a type of DCs which process the antigen to activate Th cells.
What is the function oof variable domain ?
Determine idiotype
What is the function of heavy chains ?
Determine the isotope
What are the types of light and heavy chains ?
L: K/Lamda
H: Gama / miu / sigma
What is the function of hinge region?
Improve flexibility
What is the function of fc?
- ADCC
- Complement fixation
- Binds to phagocytes
What is the function of paratopes?
- Traps antigen
- Neutralization
- Direct anti-microbial
What are the characteristics of IgM?
- First Ig:
A. Produced in an 1ry immune response
B. Synthesized in a neonate - Most eff in binding to an antigen
- Capable of agglutination: clumping antigens into large aggregates
- More eff in comp activation
What is the requirements of comp activation?
complement activation requires 2 Fc regions in close proximity
IgG fulfills this requirement
What is the function of IgG 1 3 4 ?
1,3,4 : cross the placenta
3; most effective comp activator
1,3: bind with high affinity to Fc receptors on phagocytic cells and mediate opsonization.
What are Alfa defensins?
They directly kill bacteria by disrupting their cell walls.
What is the function of IgE?
Binds to the Fc receptors on the membrane of basophils and mast cells to induce degranulation resulting in allergic manifestation or mediate effector functions needed for anti-parasitic defense.
What is the major effector function of the antibody mediated responses (humoral branch of the immune response)?
Complement system
How can the complement components be activated ?
1, classic pathway: antigen-antibody dependent
- Alternative: antigen-antibody independent
What are the mechanisms of complement system ?
- MAC attack (Cb6/7/8/9 )
- Inflammatory response ( C3a/4a/5a )
- Opsonization ( C3b ): ADCC with the help of comp system
- Solubilization and clearance of immune complexes by the liver/spleen macrophages ( C3b )
Why is any APC a phagocytic cell?
Bcz it engulfs the antigen and presents it
How does IgA exist in the serum and in the external secretions
Serum : monomers
Sec: dimerization
