15 - introduction to immunity

Question 1

what is immunity?

Answer 1

the ability of an organism to resist a particular infection or toxin by the action of specific antibodies or sensitised WBCs

Question 2

how do we gain immunity?

Answer 2

ACTIVE
• natural - natural infection
• artificial - immunisation

PASSIVE
• natural - placental transfer of maternal IgG
• artificial - human IgG

Question 3

what are the 2 types of immunity?

Answer 3

innate

adaptive/acquired

Question 4

what is innate immunity?

Answer 4

• present from birth
• simple recognition systems
• limited capacity
• there before infection starts
• patrols for infection
• rapid response - minutes
• no immunological memory

Question 5

what is adaptive/acquired immunity?

Answer 5

• not present from birth
• learns from invading organisms
• sophisticated - highly specific recognition
• specific memory
• slower response - days

Question 6

what is SCID?

Answer 6

severe compromised immunodeficiency

not born with innate immunity

Question 7

goal of the immune system

Answer 7

• to clear potential pathogens in a controlled and efficient process
• minimal side effects
• no pathology in host
• appropriate duration
• return to homeostasis
• future protection
• no self attack
• remove potential tumours

Question 8

factors affecting our immunity?

Answer 8

• general health
• infection
• nutrition
• adverse environmental conditions
• state of microbiome
• pregnancy
• genetic disorders

Question 9

what is a vaccine?

Answer 9

a substance used to stimulate the production of antibodies and provide immunity against 1 or several diseases

prepared from the causative agent of a disease, its products, or a synthetic substitute, treated to act as an antigen without inducing the disease

exposure to the antigen causes an immune response which will protect you in the future

Question 10

what is herd immunity?

Answer 10

immunising the majority of the population

susceptible people are indirectly protected

Question 11

why is there no vaccine for malaria?

Answer 11

• costs
• logistics
• time
• complexity

Question 12

4 main groups of vaccines

Answer 12

• live
• inactivated
• attenuated
• subunit

Question 13

live vaccines

Answer 13

small amount of a live virus

eg. MMR

Question 14

inactivated vaccines

Answer 14

organisms are dead but whole organism injected

Question 15

attenuated vaccines

Answer 15

live organism but has its virulence removed

eg. smallpox

Question 16

subunit vaccines

Answer 16

little bits of the virus/bacteria used to cause an immune response

cheapest and most efficient way

eg. meningitis

Question 17

immunity can either by humoral or cellular, whats the difference?

Answer 17

humoral - in the blood (antibodies)

cellular - in the cells of the immune system

Question 18

what are antibodies?

Answer 18

produced by plasma cells which are mature B lymphocyte cells

Question 19

what is clonal selection?

Answer 19

1. a single progenitor cell gives rise to a large number of lymphocytes, each with a different specificity
2. removal of potentially self-reactive immature lymphocytes by clonal deletion
3. pool of mature naive lymphocytes
4. proliferation and differentiation of activated specific lymphocytes to form a clone of effector cells

Question 20

cells of the immune system

Answer 20

all start as pluripotent stem cells

common/myphoid differentiates into T cells, B cells, NK cells and ILC

• B cells produce antibodies
• T cells are antigen specific
• NK cells and ILC are not specific and cannot recognise antigens - part of the innate response as they cannot adapt

Question 21

what do monocytes do?

Answer 21

monocytes circulate in the blood and differentiate into macrophages in the tissue

Question 22

what are primary lymphoid tissues?

Answer 22

central lymphoid organs
•bone marrow
• thymus

produce and mature lymphocytes

Question 23

bone marrow

Answer 23

a soft, spongey, highly cellular tissue that fills the internal cavity of bones

produces B cells and T cell precursors (virgin lymphocytes)

Question 24

thymus

Answer 24

a 2 lobed organ

produced T cells
only 2-4% mature and exit the thymus

Question 25

what are secondary lymphoid tissues?

Answer 25

peripheral lymphoid tissues 
•lymph nodes 
• spleen 
• tonsils 
• mucosal associated lymphoid tissues (MALTs)

lymphocytes recirculate and if they meet antigen, unto clonal expansion and differentiate in the tissues

circulate in fluids - blood and lymph

adaptive immune responses occur in the secondary lymphoid tissues

Question 26

where do B cells start to proliferate?

Answer 26

in the germinal centres of lymph nodes

Question 27

what is MALT?

Answer 27

mucosal associated lymphoid tissue

a diffuse system of non-encapsulated, submucosal lymphoid tissue in the intestinal and respiratory tracts

Question 28

respiratory MALTs

Answer 28

• nasopharyngeal lymphatic tissues (tonsils and adenoids)

* bronchus associated lymphatic tissue

Question 29

intestinal MALTs

Answer 29

• Peyer’s patches
• appendix
• isolated follicles in intestinal mucosae

Question 30

different effector mechanisms depend on:

Answer 30

• type of pathogen
• localisation
• stage of infection
• challenge