Module 2: Normal Leukocytes (lymphocytes)

Question 1

Leukopoiesis

Answer 1

production of wbc

Question 2

Where are leukocytes produced

Answer 2

bone marrow (neutrophils, eosinophils, basophil, monocyte, few lymphocytes)
lymphatic tissue (lymphocytes, plasma cells)

Question 3

Leukopoietins

Answer 3

specific “poietin” that causes a cell to transform into a mature form

Question 4

cytokines with leukopoietin activity (4)

Answer 4

Interleukins 1-19
GM-CSF (granulocyte/monocyte colony stim factor)
G-CSF (granulocyte)
M-CSF (macrophage)

Question 5

2 major functions of leukocytes

Answer 5

Production of chemical mediators and antibodies result in:
phagocytosis of foreign antigen that is labelled by antibodies
Lysis of foreign and infected body cells by direct killing mechanisms

Question 6

overall functions of leukocytes (6)

Answer 6

Encounters
Recognition
Activation
Deployment
Discrimination
Regulation

Question 7

Function: encounters

Answer 7

encounters between foreign antigens and recognition cells (lymphs and macros)

• continuous flow of circulation through lymph nodes
• large # of lymphs and motile macros circulating in blood/lymph/tissue on patrol for foreign antigens

Question 8

Function: Recognition

Answer 8

antigen specific receptor molecules on surface of lymphs and production of specific antibody molecules to bind and identify homologous antigens

Question 9

Function: Activation

Answer 9

lymphs activated when antigen is recognized as foreign

produce antibodies that direct the activities of other cells for immune response

Question 10

Function: Deployment

Answer 10

lymphs unable to destroy antigen by itself
deploys forces and amplify/distribute their own defences and collaborate with non-antigen-specific phagocytes to destroy antigen

Question 11

Function: Discrimination

Answer 11

essential to differentiate between self and foreign antigen (avoid autoimmune tissue damage)

Question 12

Function: Regulation

Answer 12

regulates intensity of immune response so that it has an appropriate antigenic response and shuts off when antigen is eliminated

Question 13

Lymphocyte responsibilities

Answer 13

detection and recognition of foreign antigen/abnormal self-antigen
initiating specific responses against the antigen
direct cytolytic killing
production of antibodies and lymphokines

Question 14

Types of lymphocytes (3)

Answer 14

B Lymphocytes
T Lymphocytes
Null Cells (killer cells, natural killer cells)

Question 15

B lymphocytes

Answer 15

primary source for humeral immune responses (antibody) by transforming into plasma cells

Question 16

T Lymphocytes

Answer 16

cellular immune responses

involved in regulation of antibody reactions by helping or suppressing the activation of B lymphs

Question 17

Null Cells

Answer 17

lack B or T cell surface markers
Killer cells: Antibody dependant cell-mediated lysis
Natural Killer cells: Direct cytotoxic activity

Question 18

How do lymphs differ from other leukocytes (4)

Answer 18

1) resting cells that undergo mitosis into memory/effortor cells when stimulated
2) recirculate back and forth between blood and tissues
3) B and T cell able to rearrange antigen receptor genes to produce different antibodies and surface receptors
4) T and Null cells develop/mature outside of bone marrow

Question 19

Site of lymphocyte maturation

Answer 19

Embryonic: developed from pluripotent cells of yolk sac and liver
Fetal-adult: stem cells in bone marrow

Question 20

What influences stem cells into lymphs

Answer 20

IL1 and IL6 turn stem cell into lymphoid stem cell (CFU-L)

then matures into primary and secondary

Question 21

Primary Lymphoid tissue

Answer 21

do not require antigenic stimulation
Thymus: stem cells multiply under cytokines to become T-lymphs
Bone marrow: stem cells become B-lymphs

Question 22

Secondary Lymphoid Tissue

Answer 22

Lymph nodes, spleen, mucosal associated lymphoid tissues
Require antigenic stimulation (an active immune response)
Acts as main storage areas of already differentiated lymphs

Question 23

Lymphoblast characteristics

Answer 23

15-20 um
N:C ratio 4:1
Nucleus: round to oval, 1-2 nucleoli, fine chromatin clumping
Cytoplasm: no granules, medium blue, may have dark blue border

Question 24

Prolymphocyte characteristics

Answer 24

15-18um
NC ratio 4:1 to 3:1
Nucleus: oval to slightly indented, 0-1 nucleoli, slightly dense chromatin clumping
Cytoplasm: may have granules, med blue with dark rim

Question 25

Lymphocyte characteristics

Answer 25

6-9um (small)
17-20um (large)
NC ratio 4:1 - 3:1 (small)
2:1 (large)
Nucleus: round to oval, may have indents, no nucleoli, dense clumped chromatin
Cytoplasm: few granules, light blue

Question 26

Lymphocyte maturation stages

Answer 26

lymphoblast
prolymphocyte
lymphocyte

Question 27

Lymphocyte maturation summary

Answer 27

nucleus gets denser and smaller
loss of nucleoli
granules may form
cytoplasmic color from dark blue to light blue

Question 28

Normal lymphocyte values

Answer 28

birth-4: higher than adults
Adults: 20-40% lymphs
of which 60-80% is T cells, 20-35% B cells
Only mature lymphs are found in peripheral blood
B and T cells cannot be distinguished from each other with routine stain

Question 29

Small Lymph characteristics

Answer 29

Nucleus: round, oval, indented, medium-deep purple, densely clumped, NO NUCLEOLI
Cytoplasm: scant to moderate amount, colourless to royal blue, rarely contains azurophilic granules

Question 30

Large lymph characteristics

Answer 30

Nucleus: Round, oval, indented, stretched, light-med purple, slightly less clumped, may contain nucleoli
Cytoplasm: moderate to abundant amount, colourless to blue, may contain azurophilic granules in a localized area

Question 31

Azurophilic granules

Answer 31

non specific granules

Question 32

Variant Lymphocyte

Answer 32

AKA atypical or reactive lymphs
“working” lymphs
normally 5-6% of lymphs seen in peripheral blood
Represent normal immune system
Increased # in viral disorders
Stimulated lymphs with increased DNA/RNA activity

Question 33

Characteristics of variant lymphs

Answer 33

increased size
nucleus folded, indented or lobulated
chromatin clumping varies (fine to dense)
nucleoli may be present (often 1-3)
Cytoplasm foamy, vacuolated, usually abundant
may have azurophilic granules
cytoplasm color from greyish to deep blue