Immunopathology Definitions

Question 1

antigen

Answer 1

molecules that bind to antibodies or T cell receptors with a high affinity

Question 2

lymphocytes

Answer 2

cells found in blood, lymphoid tissues and most organs of body that express receptors for specific antigensand mediate immune responses
- the lymphocytes that we will talk most about are B cells and T cells (B cell= B lymphocyte; T cell= T lymphocyte)

Question 3

Effector Cells

Answer 3

Mature, activated B and T cells

Question 4

Plasma Cells

Answer 4

Mature B cells; secrete antibodies

Question 5

Antibodies

Answer 5

glycoproteins bind antigens with high affinity and help eliminate those antigens

Question 6

Humoral immunity

Answer 6

adaptiev immunity that is mediated by antibodies produced by plasma cells. main mechanism for defending against extracellular microbes and their toxins.

Question 7

cell mediated immunity

Answer 7

adaptive immunity mediated by T lymphocytes; am defence mechanism against microbes that survive within phagocytes (i.e. bacteria that cause tuberculosis) or that infect the cytosol of non phygocytic cells (i.e many viruses)

Question 8

Cytokines

Answer 8

secreted proteins that work as mediators of immune and inflammatory reactions. Cel cell cross talk mechanism

Question 9

Name tissues of immune system. 1 (5), 2 (2)

Answer 9

PERIPHERAL LYMPHOID TISSUES
1. lymph nodes
2. pharyngeal tonsils
3. lymph follicles in intestine wall
4. lymphocytes in peripheral gland
5. spleen
CENTRAL LYMPHOID TISSUES
1. thymus
2. bone marrow

Question 10

What are the 2 host defences that cooperate to protect the body?

Answer 10

EARLY RAPID RE OF INNATE IMMUNITY

1. 1st line defence, can funky immediately as effective barrier to microbes
2. comp mainly skin, mucus me, phagocytic leucocytes, specialised lymphocytes, plasma proteins

LATER, VERY EFFECTIVE RESPONSES OF ADAPTIVE IMMUNITY

1. specific, acquired, using focused recognition of each unique type of foreign agent
2. humoral: B lymphocytes secreting antibodies (Ab) neutralising or eliminating microbes and microbial toxins
3. cell mediated: defends against intracellular pathogens. Protection provided by T lymphocytes that either activate phagocytes or directly kill infected cells

Question 11

Describe one of the 2 host defences that cooperate to protect the body ( EARLY RAPID RESPONSES OF INNATE IMMUNITY)

Answer 11

1. 1st line defence, can funky dimmed as effective barrier to microbes
   comp mainly skin, mucus me, phagocytic leucocytes, specialised lymphocytes, plasma protein

Question 12

Describe one of the 2 host defences that cooperate to protect body (LATER, V/ EFFECTIVE RESPONSES OF ADAPTIVE IMMUNITY)

Answer 12

1. specific acquired, using focused recognition of each unique type of foreign agent
2. humoral: B lymphocytes secrteting antibodies 9Ab) neutralising or eliminating microbes and microbial toxins
3. Cell mediated: defends against intracellular pathogens. Protection provided by T lymphocytes that either activate phagocytes or directly kill infected cells.

Question 13

What are the roles of Dendritic cells/

Answer 13

1, like phagocytic leucocytes, Dcells are capable of phagocytosing microbes that pass through epithelial barriers.

2. DC’s express receptors that recognise general classes of microbes and are known to make various cytokines in response to various microbes
3. they are also an important initial defence against viruses
4. importantly Dendritice cells are major cell ypes that capture and displays antigens to T cells, thus they from a critical link btw innate and adaptive immunity

Question 14

General differences between innate(5) and adaptive immunity (2)

Answer 14

INNATE IMMUNITY:

1. physicla and chem barriers
2. phagocytic leukocytes
3. dendritic cells
4. natural killer cells
5. plasma proteins (complement)

ADAPTIVE IMMUNITY:

1. humoral immunity : ( B cells which mature into antibody secreting plasma cells)
2. cell- mediated immunity (T cells, which mature into effector helper and cytotoxic T cells)

Question 15

5 characteristic differences between innate/ adaptive immunity

Answer 15

1. always present/ normally silent
2. immediate RE but limited and lower potency/ slower RE (over 1-2 wks, much more potent)
3. general: can recognise gen classes of pathogens (i.e. bacteria, viruses, fungi, parasites) but cannot make fine distinctions// recognises highly specific antigens
4. attempts to immediately destroy the pathogen, and if it can’t, it contains the infection until the more powerful adaptive immune system acts// slower response: effector cells are gen prod in 1 wk and the entire RE occurs over 1-2 wks. However this course can vary somewhat during different responses in an individual
5. No– rectis with equal potency upon repeated exposure to the same region// yes– memory cells “remember’ specific pathogens; upon re-exposure to a pathogen, these cells mount a much faster more potent second RE

Question 16

The complement system

Answer 16

1. major effector of both humeral and innate immunity
2. group of proteins (C1 to C9) present in the plasma in an active form
3. highly regulated process involving cascade of cleavage products capable of haemolytic activity:
   - -> initial activation phase (3 pathways)
   - -> early step inflammatory responses ( enzymatic cleavage of C3 in C3a and C3b)
   - -> Late step me attack responses: membrane attack complex 9MAC)= C6b=> cell lysis

Question 17

where are immune responses located?

Answer 17

immune respons involves events that unfold both locally at site of infection and at more distant sits such as nearby lymph nodes

Question 18

How can we see the integration of the diff parts of immune responses

Answer 18

by following the course of a typical infection

Question 19

where are most pathogens kept?

Answer 19

outside of the body by epithelial barriers such as the epidermis and are crossed only when there is an injury or tissue damage

Question 20

What happens after an injury?

Answer 20

bacteria cross epidermis and eat an infection in underlying tissue

Question 21

what happens when bacteria cross epidermis?

Answer 21

phagocytic cells in tissues such as macrophages and neutrophils engulf the pathogen

Question 22

what type of cells are also phagocytic/

Answer 22

dendritic cells.

Question 23

how are dendritic cells activated?

Answer 23

by binding pathogens to leave site of infection and migrate to a lymph node

Question 24

what are collected in a draining lymph node?

Answer 24

migrating dendritic cells which enter the lymphatic vessels

Question 25

What occurs in the lymph nodes?

Answer 25

1. T cells are activate by antigen presented by dendritic cells and in turn
2. activates B cells to secrete antibody
3. effector T cells and antibody molecules return to circulation

Question 26

When returning to circulation where do effector t cells and antibody molecules leave?

Answer 26

the circulation again at the site of infection, where inflammatory mediator shave induced changes in blood vessel endothelium.

Question 27

what do CD4 T cells and antibody do?

Answer 27

activate macrophages to become more cytoxic while antibody recruits complement to lyse bacteria directly and to opposing them, enhancing their uptake by phagocytes

Question 28

what happens in case of a viral infection

Answer 28

activated CD* T cells would kill any infected uptake by phagocytes