Immunology: Cells & Tissues of the Immune System ; Innate Immune Response

Objective: What lymphoid organs are involved in antigen-independent differentiation?

Bone Marrow

Objective: What lymphoid organs are involved in antigen-dependent differentiation?

Thymus

Objective: Name the primary lymphoid organs and their function in the immune system.

Bone Marrow (hematopoiesis),

Thymus (maturation of T-Cells)

Objective: Name the secondary lymphoid organs and their function in the immune system.

Spleen (Red Pulp: removing old/damaged cells and foreign antigen from the blood ; White pulp: lymphocytes and macrophages encounter antigen)

Lymph Vessels/Lymph Nodes (Lymphocytes come in contact with antigen from tissues ; B cell maturation occurs in the germinal center where they come in contact with Antigen and proliferate),

Adenoids, Tonsils, MALT, GALT, BALT

Objective: What are the major cells of innate immunity?

Granulocytes (Neutrophils, Eosinophils, Basophils), Monocytes, Macrophages, Dendritic Cells, Mast Cells, NK Cells

Objective: What are the major cells of adaptive immunity?

B Cells, T Cells (NK Cells)

What is the difference between primary and secondary lymphoid organs?

Primary lymphoid organs are where hematopoietic stem cells/hematopoietic progenitor cells become the "immature" versions of immune cells ready to encounter foreign Antigen. Secondary lymphoid organs are where lymphocytes encounter antigen, proliferate, and differentiate

What is the difference between the spleen and lymphatic vessels in terms of their sources of antigen?

The spleen comes in contact with circulation Antigen from blood and lymphatic vessels come in contact with circulating Antigen from tissues

What are the two arms of the immune system?

Innate and Adaptive Immunity

Define the general function of the innate immune system

Recognize traits/patterns shared by a broad range of pathogens using a set of germ-line encoded receptors

Define the general function of the adaptive immune system

Receptors on T/B cells recognize specific antigens, with the capability of being recalled ("memory")

Which arm of the immune system results in a rapid response (where the other results in a slower response)

Innate

Which arm of the immune system is present immediately at birth?

Innate

What are the two sources of defenses for the innate arm of the immune system?

Barrier Defenses and Internal Defenses

What are examples of barrier defenses and what arm of the immune system do they belong?

Innate ; skin pH, mucous membranes, hair, secretions

What are the mechanisms used for the internal defenses of the immune system?

Phagocytic cells, antimicrobial proteins (complement, lysozymes, and interferons), inflammatory responses, and NK cells

Differentiate between the two types of responses of the adaptive immune system

Humoral Response (antibodies defend against pathogens in body fluids, driven by B-Cells) ; Cell-Mediated Response (Cytotoxic lymphocytes defend against infection of our own body cells, driven by NK cells and T-Cells)

What are the major cells within the peripheral blood that play a key role in the innate immune system?

Granulocytes (Neutrophils, Eosinophils, Basophils) and Monocytes

What are the major cells within the tissues that play a key role in the innate immune system?

Macrophages, Dendritic Cells, and Mast Cells

What is the most abundant wbc?

Neutrophils

What wbc is the first to respond to an immunogenic stimulus?

Neutrophils

What is the average life-span of a neutrophil?

6 hours

What wbc makes up about 1-3% of your total wbcs and plays a key role in allergic reactions and parasitic infections

Eosinophils

What wbc is the least numerous

Basophils

What is the half life of a basophil (Hint! It's the shortest!)

2 hours

What is the basophil responsible for in an immune response?

Type 1 Hypersensitivities

What organelles do monocytes contain that are instrumental in their main role as an immune cell?

Vacuoles (Phagocytosis)

What type of cells do monocytes become when they migrate to the tissues?

Macrophages

What are the largest, eating cells of the tissues?

Macrophages

How long does it take for macrophages to arrive to the scene of an immunogenic stimulus?

4-6 hours

What innate, immune cell is the most important for antigen presentation?

Dendritic Cells

What cell of the innate immune system triggers the adaptive immune response?

Dendritic Cells

What cells are essentially the basophils of the tissues?

Mast Cells

What are the two ways in which a Natural Killer cell can eliminate an invader? Describe both.

1. Inhibitory Receptors:

If a normal, unafflicted cell comes in contact with an NK cell, the activating receptor of the NK cell will bind the the activating ligand of the unafflicted cell. Additionally, the inhibitory receptor of the NK cell will bind with the MHC Class 1 presented on the normal, unafflicted cell. This causes the NK cell to practice restraint and inhibition. However, If MHC class 1 is not present (and activating receptor of the NK cell is bound to the activating ligand of the other cell), it will initiate cell lysis by method of Perforin & Granzyme.

2. Antibody-Dependent Cell Cytotoxicity (ADCC):

If the CD16 receptor of the NK cell is able to bind with a virally infected cell, coated with IgG, it initiates the infected cell to undergo apoptosis via cell cytoxicity.

What are the four families of PRRs relevant to innate immunity

Toll Like Receptors (TLR)

Nod Like Receptors (NLR)

C-Type Lectin Receptors

Retinoic Acid-Inducible Gene 1 Like Receptors

In the innate response, PRRs recognize PAMPS... what do these stand for?

Pattern Recognition Receptors recognize Pathogen Associated Molecular Patterns

What cells of the innate immune response are capable of phagocytosis?

Macrophages/Monocytes, Eosinophils, Neutrophils, Dendritic Cells

Describe phagocytosis WITH oxygen

Occurs inside the phagolysosome and entails a respiratory burst (production of toxic metabolites and free radicals)

Describe phagocytosis WITHOUT oxygen

Occurs outside the phagolysosome: Lysozyme, Elastase, Defensin, and Perforin/Granzyme

What is the sequence of events in phagocytosis?

1. Chemotaxis/Adherance

2. Opsinization

3. Surround bacteria

4. Phagosome

5. Phagosome + Lysosome = Phagolysosome

6. Death/Digestion of Microorganism

7. Release of debris

What mediates inflammation in the innate immune response?

Cytokines and Acute Phase Proteins

Inflammation is characterized by (4 things INTERNALLY), which result in (4 things EXTERNALLY)

Increased blood flow, vasodilation, soluble mediators, and cellular influx

Swelling, pain, redness, heat

What are the inflammatory cytokines associated with inducing a fever?

IL-1Beta, IL-6, TNF-Alpha

What are the steps of eliminating a pathogen in the case of inflammation?

1. Adherance

2. Diapedesis (movement of leukocytes through endothelial cells)

3. Chemotaxis (movement of chemokines via concentration gradient towards inflammation)

4. Phagocytosis

5. Glycolysis

6. Degranulation

7. Digestion / Cytokine Release

In the adaptive immunity arm, what is an example of Naturally Active acquisition?

Getting infected or in contact with a pathogen

In the adaptive immunity arm, what is an example of Naturally Passive acquisition?

Antibodies passing from mother to baby from birth, placenta, or breastfeeding

In the adaptive immunity arm, what is an example of Artificially Active acquisition?

Vaccinations

In the adaptive immunity arm, what is an example of Artificially Passive acquisition?

Serum transplants

Which arm of the immune response would be MOST detrimental to lose?

Innate