Lecture 8 Blood: WBCs, Infection and Immunity (Ch. 34, 35)

Question 1

When do eosinophils increase?

Answer 1

during parasitic infection or allergy

Question 2

Mast cells are the mature form of what WBC?

Answer 2

Basophils

Question 3

What WBC type plays a role in attacking cancer cells?

Answer 3

Lymphocytes

Question 4

What are the two types of acquired immunity?

Answer 4

cell-mediated (T cells) and humoral (B cells)

Question 5

In T-cell epitope recognition; what do MHC I & MHC II do?

Answer 5

MHC I- binds CD8 co-receptors on cytotoxic T cells

MHC II- binds CD4 co-receptors on Helper T cells

Question 6

State differences between CD4 and CD8.

Answer 6

CD4- bind MHCII to stimulate lymphokine production and B cell proliferation
CD8- binds MHC I to rapidly attack target

Question 7

What are platelets in relation to megakaryocytes, and what are the approximate sizes of both types of cells?

Answer 7

platelets are fragments of megakaryocytes (~2 um) and megakaryocytes are ~100 um).

Question 8

What are the key contents of platelets and their functions?

Answer 8

-thromosthenin: actin/myosin contractile proteins
-ER/GA for secretory granules
-mitochondria: ATP for clotting
-fibrin stabilizing factor
PDGF: capillary and blood vessel epithelium repair

Question 9

What is a “band shift,” and what does it indicate?

Answer 9

A “band shift” is an increase in “band cells,” referring to the horseshoe shaped “band in neutrophils. It indicates a proliferate of neutrophils as a sign of disease.

Question 10

Describe the inflammatory response cascade of tissue macrophages.

Answer 10

1. increased local blood flow
2. increased vessel permeability
3. margination: capture of PMNs or macrophages
4. Diapedesis: movement through vessel wall
5. Chemotaxis to target

Question 11

What are the chemotactic agents involved in the inflammatory response that we learned about?

Answer 11

histamine, bradykinin, serotonin, prostaglandins, cytokines, lymphokines, complement proteins, clotting components, debris

Question 12

What is the role of bradykinin in the inflammatory response?

Answer 12

It increases vessel wall permeability and diameter

Question 13

What effect do cytokines have during neutrophil invasion as part of the inflammatory response?

Answer 13

Cytokines increase selectin and ICAM-1 expression on endothelial cells. They bind PMN integrins to promote adhesion prior to migration to site of injury. Selectins trap neutrophils on endothelial cells, as they would otherwise roll throught the top of the endothelial cell.

Question 14

Which enzymes increase the efficacy of phagocytosis of neutrophils and tissue macrophages?

Answer 14

lysozymes and lipase

Question 15

What is the timeline of the inflammatory response?

Answer 15

1. immediate: tissue macrophages phagocytize and release cytokine
2. Hour 1: cytokines (TNF-alpha, IL-1) cause: release of stored PMNs from 5k to 25k/ul; neutrophilia; up-regulation of adhesion molecules (selectin, ICAM-1); induce leukocyte proliferation
3. Hours 1 - 8: margination, diapedesis, and chemotaxis of phagocytic cells to target
4. Hour 8 - days: secondary PMNs and macrophages become available for additional phagocytosis

Question 16

Where do monocytes localize once they mature to macrophages in tissues?

Answer 16

1. lymph nodes (walls of sinuses to ingest material)
2. liver (Kupffer cells): detoxify hepatic portal blood system
3. lung (alveolar macrophages): ingest particles and microbes in airway
4. spleen: found in red pulp to filter blood
5. skin (histiocytes): wound protection

Question 17

What is the difference between innate and acquired immunity?

Answer 17

Innate immunity involves a rapid response to a microbe/toxin that is intrinsic and rapid (takes minutes, hours), involving the skin, HCl in stomach, PMNs/macrophages, complement, antimicrobial agents
Acquired immunity involves an induced response that can be cell-mediated (T cells) and/or humoral (B cells)

Question 18

What are the effects of the complement system?

Answer 18

1. Opsonization and phagocytosis
2. Lysis (lytic complex C5b6789)
3. Agglutination
4. Neutralization of viruses
5. Chemotaxis
6. Activation of mast cells and basophils
7. Inflammatory effects

Question 19

Describe the steps of B cell maturation

Answer 19

B cells clones proliferate in the bone marrow

1. Antibody selection: B cell clones bind antigens
2. Clones expand to generate array of specific antibodies; migrate to lymph nodes
3. Antibody secretion: antigen recognition triggers pathogen destruction

Question 20

Which lymphokine(s) promote(s) proliferation of T cells?

Answer 20

Interleukin-2 promotes proliferation of CD-8 T cells (cytotoxic T cells), CD4 T-cells (T helper cells), and suppressor T cells.

Question 21

Which lymphokine(s) promote(s) proliferation of B cells?

Answer 21

Interleukin-4, -5, and -6 are B-cell growth factors (BCGFs).

Question 22

Which lymphokine promotes leukocyte proliferation?

Answer 22

GM-CSF; it enhances the phagocytic capacity of the the immune response

Question 23

Whih lymphokine acts as a macrophage activator?

Answer 23

Interferon gamma

Question 24

Which types of cells are targets of cytotoxic T cells?

Answer 24

virus-infected cells, cancer cells, and tissue transplants

Question 25

Describe the classical complement pathway.

Answer 25

Antigen-antibody complexes allow Fc domains (antibody tails) to bind C1 which complexes with C4 on C2. C4/2 activates alternative pathway protective mechanisms.

Question 26

Describe the alternative complement pathway.

Answer 26

Microbes bind Factors B and D (innate) which activates C3.

1. C3b triggers phagocytosis (opsonization)
2. C3a (also C5a) mast cell activator; histamine and heparin release increase local blood flow
3. C5a chemo-attractant for PMNs and macrophages
4. C5b + 6789 form lytic complex that ruptures bacterial cell membranes.

Question 27

What constitutes pus?

Answer 27

accumulated material (dea bacteria, PMNs, macrophages, necrotic tissue) as a result of infection

Question 28

What is the pathophysiology of rheumatic fever?

Answer 28

streptococcal antigens produce antibodies that cross-react with host tissues; may lead to post-streptococcal glomerulonephritis and/or rheumatic endocarditis

Question 29

Describe the classifications of leukemia by tissue origin

Answer 29

• Lymphocytic: lymphoid; often metastatic

- Myelogenous: bone marrow; unlikely to spread (involving neutrophils, eosinophils, basophils, monocytes)