Leukocytes

Question 1

lymphoid (adaptive)

Answer 1

Th (helper) lymphocyte, Tr (regulatory) lymphocyte, Tc lymphocyte (or cytotoxic T cell), B lymphocyte, plasma cell

Question 2

lymphoid (innate)

Answer 2

Natural Killer (NK) cell (null)

Question 3

granulocytic myeloid cells

Answer 3

neutrophil, basophil, mast cell, eosinophil

Question 4

antigen-presenting myeloid cells

Answer 4

sentinel dendritic cell, monocyte, macrophage

Question 5

NOT from hematopoiesis

Answer 5

follicular dendritic cells

Question 6

T_h (helper) lymphocyte

Answer 6

Function: Activates inflammation, macrophages, and B cells

Characteristics: coordinates immune response

Surface expression: CD4, receptors for class II, MHC plus antigen

Responds to: antigen presented on class II MHC

Releases: variety of cytokines

Question 7

T_R (regulatory) lymphocyte

Answer 7

Function: suppresses immune response, generally and of specific lymphocytes

Characteristics: prevents allergy and autoimmune diseases

Surface expression: CD4 and CD25 when naive

Responds to: mechanism of action still mysterious

Releases: Cytokines: IL-10, TGFß

Question 8

T_C lymphocyte (or cytotoxic T cell)

Answer 8

Function: destroy altered-self cells

Characteristics: kills viral infected and malignant cells

Surface expression: CD8, receptors for class I, MHC plus antigen

Responds to: Antigen presented on class I MHC

Releases: perforin and granzymes

Question 9

B lymphocyte

Answer 9

Function: recognize antigen, can present antigen to T cell

Characteristics: develops into plasma cell

Surface expression: membrane bound antibodies, class II MHC, complement receptors 1 and 2

Responds to: circulating antigen, T_H cytokine signals

Releases: nothing

Question 10

Plasma cell

Answer 10

Function: secretes antibodies

Characteristics: mature B cell, lives 1-2 weeks

Surface expression: no surface antibodies

Responds to: T_H cytokine signals

Releases: antibodies

Question 11

Natural Killer (NK) cell (null)

Answer 11

Function: destroy altered-self cells

Characteristics: Kills viral infected and malignant cells. Can recognize altered-self on first exposure

Surface expression: CD16-binds Fc (stem) of antibodies, MHC receptor-when activated, inhibits killing

Responds to: antibodies and down-regulated MHC I

Releases: perforin and granzymes

Question 12

neutrophil

Answer 12

Function: phagocytosis, part of inflammatory response. Move into infected tissues

Characteristics: picks up both acidic and basic dyes, hydrolytic enzymes in granules

Surface expression: Fc and complement receptors

Responds to: chemokines

Question 13

basophil

Answer 13

Function: important in allergy

Characteristics: picks up basic dyes e.g. methylene blue

Surface expression: Fc receptors for IgE

Responds to: chemokines

Releases: prostaglandins and leukotrienes

Question 14

mast cell

Answer 14

Function: inflammatory response, especially to allergens

Characteristics: mature cells in skin, mucosal, digestive tract and other first defense tissues

Surface expression: Fc receptors for IgE

Question 15

Eosinophil

Answer 15

Function: defense against parasites

Characteristics: pick up acidic dyes, e.g. eosin

Surface expression: Fc receptors for IgE

Responds to: chemokines

Releases: anti-helminth agents

Question 16

sentinal dendritic cell

Answer 16

Function: process and present antigen to T_H cells

Characteristics: covered with PM extensions, potent antigen presenters

Surface expression: Class II MHC, B7, toll-like receptors

Question 17

monocyte

Answer 17

Function: macrophage precursors

Characteristics: circulate in blood for 8 hours, then differentiated into macrophage

Question 18

macrophage

Answer 18

Function: phagocytosis of microorganisms and debris, present antigen after activation

Characteristics: move through tissues, differentiated from monocytes

Surface expression: Class II MHC, toll-like receptors

Responds to: Interferon from TH

Question 19

follicular dendritic cells

Answer 19

Function: feed antibody-antigen complexes to B cells

Characteristics: found in secondary lymphoid organs

Surface expression: receptors to hold antibody-antigen complexes