Cells and Organs of the Immune System Flashcards
What is the 1st line of innate immunity?
Skin, mucous membranes, chemicals
What is the 2nd line of innate immunity?
Phagocytosis, complement, interferon, inflammation, fever
What is the 3rd line of immunity?
ADAPTIVE IMMUNITY
Lymphocytes, antibodies
Which of the following has a delayed immune response? Innate or Adaptive
Adaptive
Which leukocytes are polymorphonuclear?
- Neutrophils
- Eosinophils
- Basophils
Where are granulocytes produced?
Bone marrow (Basophils, Eosinophils, Neutrophils)
Characteristics of basophils
- toxic granules stain dark blue
- involved in allergic and inflamm. responses
- defense against parasites
- PHAGOCYTOSIS
- expresses adhesion molecules
Characteristics of Eosinophils
- granules stain red
- defense against PARASITES and ALLERGIES
-Responds to chemokines secreted by neutrophils or lymphocytes
What is the function of recruited eosinophils?
Releases toxic granules to destroy pathogens and fight infection
Characteristics of neutrophils
- granules stain pale pink
- most numerous, first to respond
-circulates bloodstream looking for foreign objects to PHAGOCYTOSE and DEGRADE (Ex: bacteria)
How is the number of circulating neutrophils estimated?
Using Absolute Neutrophil Count (ANC)
When would ANC be high? (Neutrophilia)
- Kidney failure
- Bacterial infection
When would ANC be low? (Neutropenia)
- Leukemia
- Bone Marrow damage
What can granulocytes be identified by?
Expression of…
- CD16
- CD34 (immature state)
- CD11b/CD18 (activated state)
How can ACTIVATED BASOPHILS be identified?
- CD13/ Aminopeptidase N
- CD107a/ LAMP1 or CD164
3.
How can ACTIVATED EOSINOPHILS be identified?
- CD44
- CD69
- IL-5
How can ACTIVATED NEUTROPHILS be identified?
- CD16
- L-selectin (CD62L)
Where are mast cells generated?
Bone marrow
Mast cell characteristics
- Defense against PARASITES
- Found in tissues that mediate allergic rxns by releasing HISTAMINE
- Similar to basophilic leukocytes
- Common progenitor: CD34+ precursor cells
What are the 2 types of mast cells?
- CT mast cells - local allergic rxn
- Mucosal mast cells - found in areas exposed to external enviro
(Ex: Mouth, Nose, Lung mucosa, Digestive tract)
Monocyte/Macrophage characteristics
- Circulates peripheral blood, enters tissues
- replenishes tissue-specific macrophage populations (Ex: Osteoclasts, microglial, kupffer cells)
- INGESTS and DEGRADES bacteria
What is a “housekeeping” function of macrophages?
Recycles dead cells (like RBCs)
Characteristics of natural killer cells
- Innate immune cells, some can be part of adaptive (NKT cells)
- Kills viruses and tumor cells
- Granules filled with proteins that make holes in the target cell
-Apoptosis
-cytotoxic effector, regulates immune response
Characteristics of dendritic cells
- SENTINEL cells
- captures, processes, and presents antigens to T cells
Promotes self tolerance
- T cell activators in secondary organs
Where do dendritic cells undergo maturation?
Bone marrow, Lymphoid, and non lymphoid tissues
How are dendritic cells classified?
- Classical/Conventional (cDCs)
- Plasmacytoid dendritic cells (pDCs)
What is the function of pDCs?
plasmacytoid dendritic cells
secretes large amounts of type I interferons upon activation through TLR7 nad TLR9
Which cell is an essential component of the humoral immune response?
B CELLS
When are B cells activated?
When they bind antigens through their receptors (BCR)
What are the functions of B cells?
Generates antibodies to specific antigens
Antibodies coat the surface of a pathogen and serve 3 major roles:
- Neutralization
- Opsonization
- Complement activation
What is neutralization?
When the pathogen is covered in antibodies and cannot further infect host
What is opsonization?
Antibodies surround the pathogen and alert neutrophils and macrophages to engulf and digest the pathogen
What is complement activation?
A process for directly destroying or lysing pathogens
some components can act as opsonins (marking pathogen for other cells to come destroy)
What is the precursor to T cells?
THYMOCYTES
Thymocytes
T cell precursor
Develops from hematopoietic stem cells in BONE MARROW, moves to mature in THYMUS
Undergoes stages of selection and quality control
Which of the following is a process by which harmful substances, such as viruses or toxins, are made harmless and unable to cause harm to the body?
a) Opsonization
b) Neutralization
c) Complement activation
d) All of the above
b) Neutralization
Which of the following is a process by which particles, such as bacteria or other pathogens, are marked for destruction by the immune system?
a) Opsonization
b) Neutralization
c) Complement activation
d) All of the above
a) Opsonization
What are the 4 major CD4+ helper cells?
- Th1
- Th2
- Th17
- T regulatory cells
What are Th1 cells?
CD4 T helper cell
coordinates response against intracellular pathogens
secretes cytokines that alert and activate other immune cells (Ex: bacteria ingesting macrophages)
What are Th2 cells?
CD4 T helper cells
coordinates immune response to extracellular pathogens
like helminths!! (worms)
alerts B CELLS, GRANULOCYTES + MAST CELLS
What interleukins are secreted by Th2 cells?
IL-10
1L-4 and IL5
What are Th17 cells?
CD4 T helper cells
makes IL-17 that activates immune and non-immune cells
protects surfaces (skin + gut) against extracellular bacteria
recruits neutrophils
What are regulatory T cells? (TREGS)
CD4 T helper cell
Monitors + inhibits activity of other T cells
How do immune cells communicate?
Cell to cell contact or through secreted signaling molecules
receptors + ligands
What are toll-like receptors?
expressed on macrophages and dendritic cells
activates innate immune cells
essential for inflammatory responses
What do T and B cells do?
Recognize foreign material
What is the functions of MHCs?
antigen presentation
signals if a cell is a host cell or foreign
What do complement cells do?
C3a + C5a
punches holes into the pathogen, creating leaks that lead to death
also signals and alerts immune cells to site of inflammation
Where are lymphoid cells first produced?
Yolk sac, fetal omentum, and liver
later produced in bone marrow
What are the secondary lymphoid organs?
- Spleen
- Lymphnode
- Peyers patches
- Encapsulated lymphoid tissue
What species develops B lymphocytes in the intestinal lymphoid tissue?
Rabbits, dogs, ruminants, pigs
