Blood Cell Immunology

Question 1

Cytokines

Answer 1

Small proteins secreted by many cell types

Mediate inflammation, immunity and hematopoiesis

Can act via endocrine, paracrine, autocrine

Have multiple functions depending on the cell type which they bind

Question 2

Cytokines of Innate Immunity are divided into 2 classes:

Answer 2

Pro-inflammatory cytokines: stimulate inflammation

Anti-inflammatory: inhibit inflammation

Question 3

Chemokines

Answer 3

(certain kind of cytokine) Are small protein chemoattractants that are used in trafficking of immune cells

Question 4

Macrophage secretes cytokines

Answer 4

True

Question 5

IL-6 effects

Answer 5

Local effects

Lymphocyte activation and increased antibody production→ fever (liver cells)

Strongest

Question 6

Leukocytosis

Answer 6

WBC count ABOVE normal range

Due to normal response of bone marrow to infection or inflammation:
-Trauma, gout, rheumatoid arthritis, rheumatic fever, thyroiditis, acute stress

In some instances, leukocytosis is a sign of a more serious primary bone marrow disease (Chronic Myelocytic Leukemias, CML)

Due to infections or inflammatory processes

Question 7

Average life span of a WBC

Answer 7

11-16 days

Leukocyte remains in circulation and tissue for how long before it dies? Only a few hours

Question 8

Leukopenia

Answer 8

Reduction in circulating WBC count (less than 4000/uL)

Question 9

Eosinophils

Answer 9

Act very quickly

Involved in allergic reaction and against parasites

Produce inflammatory mediators-cytokines, prostaglandins, leukotrienes

They are WBC that participate in immunologic and allergic responses

Question 10

Mast cells are granulocytes

Answer 10

True

Mast: tissue-fixed (can amplify or suppress immune response)
Basophils: circulating in blood

Question 11

Markers on T cells

Answer 11

CD 3,4,8

Question 12

Markers on B cells

Answer 12

CD 19,20

Question 13

Markers on Dendritic Cells

Answer 13

CD 11c,123

Question 14

Markers on NK Cells

Answer 14

CD 56

Question 15

Markers on Stem Cells

Answer 15

CD 34 (HSC)

The majority of cell types involved in immune system come from this cell

HSC found in fetal liver, fetal spleen, bone marrow

Question 16

Markers on Macrophages/Monocytes

Answer 16

CD 14,33

Question 17

Markers on Granulocytes

Answer 17

CD 66b

Question 18

CBC and DIFF

Answer 18

Complete Blood Count (lab test)

Differential leukocyte count

*Use both tests together to get a complete hematologic picture

Question 19

Neutropenia

Answer 19

Reduced number of neutrophils

If severe, can lead to life-threatening infection. Often caused by chemotherapy or radiation therapy

Suspect neutropenia in people who have frequent or unusual infections

Question 20

Eosinophilia

Answer 20

x>500/mcL

Common causes: allergic events and parasitic infections

Question 21

Mast cells

Answer 21

In areas that are exposed to the environment (skin, airways, GI etc). Close to blood vessels

Mast cells express receptors for many pathogen-associated (PAMP) and damage-associated molecular patterns (DAMP)

They can amplify or suppress immune responses

Question 22

How are mast cells activated?

Answer 22

Crosslinking of IgE bound to high-affinity receptors for IgE

Question 23

Major mediators released by mast cells

Answer 23

Histamine
TNFα
IL-8 (attracts neutrophils)…rolling

Question 24

What cytokine is released by mast cells that attracts neutrophils?

Answer 24

IL-8

Question 25

Neutrophils

Answer 25

Mediate earliest phases of inflammatory reactions

Stimulate inflammatory mediators-cytokines, prostaglandins, leukotrienes

Release NETs which have a core DNA element. They immobilize pathogens. They continue working after secreting NETs

Question 26

What stimulates the production of neutrophils?

Answer 26

A cytokine called granulocyte colony-stimulating factor (G-CSF)

After entering tissues, they only survive for 1-2 days

Question 27

Macrophages

Answer 27

Involved in wound repair
Can secrete a variety of cytokines and chemokines (defensins, cationic proteins, lipases)
Produce large amounts of TNF, IL-1β, IL-12, IL-23

Interferon-γ makes positive feedback loop

Drivers of chronic inflammatory and autoimmune disease (because of TNF, IL-1β)

They present the Ags to T-helper cells, which activates T-cells and production of cytokines that further activate the macrophage

Question 28

Fibronectin

Answer 28

Glue-like, connects neutrophils and their targets

Question 29

NK cells can be increased by what factors?

Answer 29

IL-15 and IL-2

activity can be enhanced by IL-2 and IFNs

Question 30

Antibody-Dependent Cellular Cytotoxicity (ADCC)

Answer 30

Can kill target cells without the need of complement if target cells are coated with specific Ab (IgG)

Thought to play role in antiviral, anti-tumor and anti-graft immunity

Has been attributed to NK cells

Macrophages and neutrophils also participate in ADCC

Question 31

Absolute white blood cell count consists of what cells?

Answer 31

basophils
eosinophils
neutrophils
monocytes
lymphocytes

Question 32

Staining

Answer 32

Mast cells: purple (using methylene blue)
Basophil: purple/blue
Eosinophil: red (w/ Giemsa)

Question 33

Activation of Mast cells

Answer 33

Mast: cross-linking of IgE. They also use TLRs

Question 34

C5a

Answer 34

Potent chemotaxin. Made from gram-negative bacteria activating complement cascade