Immunogenetics

Question 1

• Have Lymphoid Progenitor for Lymphocytes
- Becomes T cell in……..
• Important in

• Becomes B cell in ……………

Answer 1

Thymus
Cellular Immunity
• Develop into CD4, CD8 or other cells
- Secretes cytokines, interleukins, etc.
- Assists B cells in making immunoglobulins

Bone Marrow
• Begins with IgM
• Matures to form other immunoglobulins
- IgA, IgE, or IgG (with subelasses IgG1-4)
• Mature cell is Plasma cell
• Immunoglobulins used to surround antigens for phagocytosis
• Responsible for Specific immunity (and memory)

Question 2

• Papaine splits the immunoglobulin molecule into three fragments?

Answer 2

• Two similar, each containing an
  antibody site capable of combining with a specific antigen antigen-binding fragment or Fab
• The Crystallizable fragment Fc

Question 3

Second line of defense

Answer 3

• Phagocytic white
blood cells
• Antimicrobial proteins
• The inflammatory
response

Question 4

The immunoglobulin molecule is made up of four polypeptide chains:
………..
……….
Each Fab fragment is composed ………..
Fc fragment is composed………

Answer 4

•Two light(L) 220 AA
•Two heavy (H) 440 AA

of L chains linked to the amino-terminal portion of the H chains,

only of the carboxy-terminal portion of the H chain

Question 5

How do we acquire so many different types of antibodies?

Answer 5

• Somatic recombination
• Junctional diversity
• hypermutations

Question 6

What is Immunoglobulin
Responsible for allergic symptoms in immediate hypersensitivity reactions

Answer 6

IgE

Question 7

Main antibody type in external secretions such as saliva and mother’s milk

Answer 7

IgA

Question 8

Main form of antibodies in circulation production increased after immunization; secreted during secondary response

Answer 8

IgG

Question 9

Function as antigen receptors on lymphocyte surface prior to
immunization; secreted during primary response

Answer 9

IgM

Question 10

Function as antigen receptors on lymphocyte surface prior to
immunization; other functions unknown

Answer 10

IgD

Question 11

The major histocompatibility
complex is a large group of genes on chromosome

Answer 11

short arm
6

Question 12

MHC Class I
Type
Found on
Recognized by
Function

Answer 12

HLA-A, HLA-B, HLA-C

All nucleated somatic cells

CD8/ TC cells

Presentation of Ag to TC cells leading to elimination of tumor or infected host cell

Question 13

MHC Class II
Type
Found on
Recognized by
Function

Answer 13

HLA-DP, HLA-DO, HLA-DR

Macrophages, B-cells,
Dentritic cells, langerhans cells of skin and activated T cells

CD4 TH cells

Presentation of Ag to TH cells which secrete cytokines

Question 14

Immunogenetic disorders
treated with

Answer 14

hematopoietic
Stem cell!transplantation.

Question 15

Severe combined immunodeficiency (SCID):
Affect …..
Onset age …….

Answer 15

the most severe forms of T cell disorders. SCID can result from
genetic mutations that affect lymphocyte production, and
development.

• Onset age at early infants(4 - 5 months)
• Recurrent infection
with fungi, virus, bacteria,
mycobacterium, protozoa
• Opportunistic infections
• Poor prognosis, early infant deaths
• Severe infection after live
virus vaccine and BCG
• GVHD after blood transfusion
High risk of malignancy

Question 16

X-linked hyper IgM syndrome:
occurs almost exclusively in
……

Patients with this disorder have

Answer 16

Male

Patients with this disorder have abnormal high levels of immunoglobulin M (IgM), and low levels of three other classes of antibodies: immunoglobulin G (IgG),immunoglobulin A (IgA), and immunoglobulin E (IgE).

Question 17

X-linked agammaglobulinemia (XLA):
due to mutation in…….

Answer 17

the molecular basis for XLA is a disruption in B cell development
Mutation in in Bruton’s tyrosine kinase (Btk) present on X
chromosome.

liable to invasive infections from
encapsulated bacteria, ,enterovirus infections

Question 18

DiGeorge Syndrome

Answer 18

• Deletion of chromosome
22q11.2
- Defective development of 3rd and 4th pharyngeal pouches
• Absence of Thymus
- Therefore low or absent T cells
- No B cell abnormalities except in more severe forms.
• Associated Anomalies
- Conotruncal Cardiac Defects
•VSD
• Tetralogy of Fallot
• Interrupted Aortic Arch
- Parathyroid Hypoplasia
• Low Calcium
•Tetany

Question 19

Chronic Granulomatous Disease

Answer 19

• Genetics
- 70 % X-linked recessive
- Defect in NADPH oxidase
- Can’t form reactive oxygen species to destroy micro-organisms
• Symptoms
- Pneumonia, Abscesses, Adenitis, Osteomyelitis
- Uniquely susceptible to Aspergillosis
• Associated Symptoms
- Severe Acne
- Excessive Granulomata - often in GI tract
- Lupus
- Chorioretinitis
• Diagnosis - Nitroblue Tetrazolium Test (NBT)
• Treatment
- Antibacterial and antifungal prophylaxis
- Interferon Gamma
- Stem cell or Bone Marrow Transplant

Question 20

Wiskott-Aldrich syndrome:

Answer 20

X-linked Recessive
• Gene defect of WAS protein
•B and T cells dysfunction
• Triad of
- Thrombocytopenia
- Eczema
- Recurrent Pyogentic infections
• Treatment - Stem cell or Bone Marrow transplant
• Prognosis - Average life expectancy 11years