Hr 4 development of immunity
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Transcript of Hr 4 development of immunity
CHAPTER 11 : IMMUNITY (5 hrs)
11.1 Immune Response (2½)
11.2 Development of Immunity (1½)
11.3 Immune Disorder ( 1 )
• Describe and explain the primary and secondary immune responses to antigen.
• Explain the concept of self and non-self recognition and its application in organ transplant, grafting and blood transfusion.
11.2 : Development of Immunity (Objectives)
Active
Natural Artificial
Passive
Types of Immunity
Immunity
Natural Artificial
Antibody from: pregnant mom to
fetus Nursing mother to
infant
Antibody from Injected antibody from
animal / people to another people
Exposed naturally to antigen
By immunization or vaccination
Passive immunity Obtain antibody from outside Effect : immediate but short-lived
Active immunity Produce own antibody due to entrance of
antigen Effect : longer time but long-lived Has immunological memory
Vaccination
For active immunity, it develops within 2 stages:-
Development of Immunity
Primary immune response
Secondary immune response
Immunity
1st exposure to the antigen
2nd exposure to the same antigen
Primary & Secondary Immune Responses
Has a longer lag period (where no antibody is produced)
Due to the time needed for the specific B cell to:
Primary Immune Response
Become activated
Proliferate (producing clone)
1
2
Differentiate (plasma cell & memory cell)
3
Plasma cell secrete antibody (mainly Ig M) Amount of antibody is relatively low After a short time, amount of antibody decrease
Has a very short lag period (due to the presence of memory B cells ~ immunological memory)
Production of antibody is :-
Secondary Immune Response
faster
higher amount
1
2
more prolonged (remain longer)
3
Antibody level tends to remain high for longer period
Plasma cell secrete antibody (mainly Ig G)
Obtained by vaccination / immunization
Obtained by injecting small amount of vaccine into the body
Which trigger immune response Effect :- produce antibody against injected
antigen Vaccine is inactivated toxins or weakened /
dead pathogen Which trigger immune system to produce
antibody, but can no longer cause disease
Artificial Active Immunity
Vaccination
Vaccination
• BCG (tuberculosis) • After birth / 13 yrs
• Hepatitis B • After birth / 1 mth / 6 mths
• Triple Antigen (DPT)-Diphteria (sore throat)-Pertusis (whooping cough)-Tetanus
• 3 / 4 / 5 mths
• Polio • 3 / 4 / 5 mths
• MMR-Measles-Mumps-Rubella
• 4 yrs
a.k.a Human Leucocyte Antigen (HLA) Is known as self antigen Each person has a unique MHC (except identical twins) That differentiate our own cells with other person
MHC
MHC
Class I Class II
found on all cells (except RBC)
found on cells involved in immune response (macrophage, B cell)
Our immune system can recognize foreign cells & own body cells
Due to presence of MHC Self antigen does not provoke immune
response Non-self antigen trigger immune response
Non-self includes:- Antigen Cells from other individuals / organisms
Self & Non-self Concept
Concept of Self & Non-self Recognition
Antigen receptors are tested for self-reactivity
Lymphocytes carrying receptors that can bind to molecules already present in the body are inactivated or destroyed by apoptosis
Only lymphocytes that recognize foreign molecules continue to develop
Helps to recognize self from non-self (self-tolerance)
Failure to recognise self antigen leads to autoimmune diseases
Self & Non-self Concept
Skin Grafting
Blood transfusion
Organ transplant
1
2
3
Transfer of blood from 1 person to another
Blood group must be determined before it can be transferred
By using ABO blood group system
Blood group can be determined by antigen found on red blood cell (RBC) membrane
Blood Transfusion
Blood Transfusion
Antibody B
Has antigen A
Blood A Blood B Blood AB
Blood O
Has antigen B
Has antigen A & B No antigen
Antibody A
No antibody
Antibody A & B
If the antigen & complementary antibody is present in the blood, agglutination occurs
Blood O universal donor Because it has no antigen on the surface
does not trigger immune response
Blood AB universal recipient Because it has no antibody (for blood)
does not cause agglutination
Blood Transfusion
Blood Transfusion
Why is it easier to transfer blood compared to transfer
organ ??
RECALL that RBC doesn’t have MHC Type of antigen present
A & B
Blood Transfusion
Skin Grafting
Replacement of damaged tissue / organs with a healthy one
3 kinds of transplant
Skin Grafting & Organ Transplant
Autografts
Isografts
1
2
Allografts3
Tissue (skin) grafted from 1 area to another on the same person
Same MHC no rejection
1. Autografts
A graft between genetically identical individuals
Identical twins Same MHC no rejection
2. Isografts
A graft from 1 individual to a genetically different individual of the same species
Different MHC may cause rejection
To minimize rejection, tissue typing is done Find a close match for both tissue donor &
recipient’s MHC (at least 75% match) In the absence of identical twins, siblings
usually provide the closest tissue-type match.
3. Allografts
MHC causes rejection of tissue graft & organ transplant
To reduce rejection, chemicals are needed to suppress the immune response (immunosupressant ~ cyclosporine)
But, it causes the recipient to be more susceptible to infection during treatment
Skin Grafting & Organ Transplant
Involve major organs (heart, renal, liver, lung)
Determine ABO blood typing Determine tissue typing (MHC matching)
Organ Transplant
Selective drugs, that suppress helper T cell activation without crippling nonspecific defense or T-independent humoral responses, can improve the success of organ transplant.
Skin Grafting & Organ Transplant