Week 2 Adaptive Immunity and T cells

Question 1

MHC class II molecule
Present ____ antigen.
present on ____ cells.

MHC class I molecule
Present ____ antigen.
Present on ____ cells

T cell activation
Activation of Helper T cells
1. ____
2. ____

Activation of Cytotoxic T cells
1. ____
2. ____

Answer 1

MHC Class II molecule
Present exogenous antigen (antigens that originate from outside the body);
e.g. abnormal proteins from infected (viral or bacteria infection) or cancerous cells
Present on dendritic cells, macrophages, and B cells.

MHC Class I molecule
Present endogenous antigen (antigens that originate from within the body’s own cells);
Present on all nucleated cells.

T Cell Activation
Activation of Helper T Cells
Helper T cell receptors bind to antigens bound to MHC class II
The activated helper T cell divides into effector helper T cells and memory helper T cells.
(further activated by cytokine released by other helper T cells)

Effector helper T cells activate B cells, helper T cells and cytotoxic T cells by releasing cytokines.

Activation Cytotoxic T Cells
Cytotoxic T cell receptors bind to antigens bound to MHC class I
The activated cytotoxic T cell divides into effector cytotoxic T cells and memory cytotoxic T cells.
(further activated by cytokine IL-2 released by helper T cells)

Effector helper T cells destroy infected or cancerous cells by
Releasing perforin and granzymes
or release cytokine to activate “death receptor” Fas on cells

Question 2

Immune System: Friends or Foe
Allergy
Immune response to a ____.
Immediate Hypersensitivity
process

Answer 2

Immune response to a nonpathogenic antigen.
Types of allergies: Immediate Hypersensitivity, Delayed Hypersensitivity
Immediate Hypersensitivity

Question 3

Blood type
ABO Blood Groups(____)
(blood type and their corresponding antibodies)
Clinical: ____ during blood transfusion
____(how)
Symptoms: ____, ____.

Rh blood Group(____)
(Blood type and their corresponding antibodies)
antibodies developed through:
1)____
2)____

Clinical: ____
____ (how)
Symptoms: ____, ____, ____.
Prevention:
_____
_____
_____

Answer 3

Allergy
Immune response to a nonpathogenic antigen.
Types of allergies: Immediate Hypersensitivity, Delayed Hypersensitivity
Immediate Hypersensitivity

Inflammation: local rashes or anaphylaxis (low blood pressure)

Blood Types
ABO Blood Groups (types of surface oligosaccharides)
Cross-reactions during blood transfusion
Antigens on donor RBC meet antibodies in the recipient’s plasma.
Symptoms: agglutination (clumping) & hemolysis

O is a universal donor and AB is a universal recipient.

Rh Blood Group (types of surface protein)
Rh-positive (have Rh group on surface) or Rh-negative (have no Rh group on surface)

Rh- individuals do not normally have anti-D antibodies.
But can develop by
Transfusion of Rh- individual with Rh+ (D antigen) blood
Pregnancy Rh- mother and Rh+ baby (D antigen)

Hemolytic disease of the newborn (HDN)
Symptoms: Anemia, jaundice, enlarged liver and spleen, and severe edema.

Prevention:
Inject anti-D antigen antibodies into Rh- mother during
and following her pregnancy.

The antibodies bind to and remove fetal red blood cells in
mother’s bloodstream before they can trigger an immune
response in the mother.
Thus, B cells are not activated in the mother and no immunological memory of the D antigen is acquired.