Introduction to the Immune System

Question 1

What are the parts of a lymph node? What kind of cells are found in each part?

Answer 1

• cortex/follicle = B
• germinal center = antibody production
• paracortex = T
• medulla = macrophage

Question 2

Which cells are part of the first line of defense?

Answer 2

macrophages and neutrophils

Question 3

granulocyte CD marker

Answer 3

CD15+

Question 4

monocyte CD marker

Answer 4

CD14+

Question 5

DC CD marker

Answer 5

CD11c

Question 6

T cell CD marker

Answer 6

CD3+

Question 7

helper T cell CD marker

Answer 7

CD4+ and CD3+

Question 8

killer T cell CD marker

Answer 8

CD8+ and CD3+

Question 9

B lymphocytes

Answer 9

CD19+

Question 10

NK cells

Answer 10

CD56+

Question 11

What are sites of antigen entry, initial capture, and collection?

Answer 11

• entry = skin, GI, lungs
• initial = connective tissue
• collection = lymph nodes or spleen

Question 12

What are self markers?

Answer 12

MHC - major histocompatibility complex
HLA - human leukocyte antigens
mark a cell as being part of the human body

Question 13

Which cells express class I MHC?

Answer 13

all nucleated cells;

Question 14

Which cells express Class II MHC?

Answer 14

B cells, monocytes, macrophages, DC

Question 15

What is an antigen?

Answer 15

• substance that generates an antibody

- can be whole cell or particles of a foreign invader

Question 16

What is an epitope?

Answer 16

multiple antigenic components that are recognized and trigger an immune response

Question 17

Describe innate immunity.

Answer 17

• short
• nonspecific
• initial
• mediated by macrophages, granulocytes, and NK cells

Question 18

Describe adaptive immunity

Answer 18

• longer duration
• specific
• mediated by B and T cells
• results in activation, differentiation, and clonal expansion

Question 19

Describe B-mediated humoral immunity

Answer 19

• APC recognition (in lymph node)
• activation
• clonal expansion
• differentiate into antibody-producing plasma cell
• produce antibody
• memory B cell

Question 20

Describe T cells

Answer 20

either produce cytokines (helper T cells) that recruit other immune cells or kill cells on contact with chemicals, like perforin or granzymes (killer T cell)

Question 21

What are the phases of an adaptive response?

Answer 21

• recognition due to APC
• activation of T and B cells
• clonal expansion
• differentiated into effector cells
• kill antigen
• memory cells remain

Question 22

Describe the mechanism of cell-mediated immunity

Answer 22

• APC breaks down antigen and displays the peptide on a Class II MHC molecule
• helper T cell receptor recognizes antigen => activation
• helper T cell produces cytokines to recruit plasma cells and killer T cells
• helper T cell cytokines allow for clonal expansion and differentiation
• differentiated killer T cells roam the body to look for that antigen, recognizing it on Class I MHC molecules

Question 23

Describe primary vs secondary response.

Answer 23

primary response = initial encounter with antigen

secondary response = faster, longer duration, and greater response

Question 24

Describe active vs. passive immunity.

Answer 24

active = through acquired infection or vaccination; body is prepared for the antigen
passive = immunity is given through exposure to antibody-rich serum (babies)

Question 25

Identify the role of MHC molecules in T cell immunity.

Answer 25

MHC molecules are present on APCs and on nucleated cells. Antigens on MHC molecules bind to T cell receptors.

Question 26

Contrast humoral and cell-mediated immunity.

Answer 26

humoral = antibody is freely floating in the blood and marks invaders and infected cells for immune cells

cell-mediated immunity = cytokines used to kill cell