Major Histocompatibility Complex Flashcards
a.k.a. Human Leukocyte Antigen
Major Histocompatibility Complex (MHC)
Where are MHCs are coded and found?
Short Upper Arm of Chromosome 6 at band 21
Three Classes of MHCs
Class I
Class II
Three principal Loci of Class I
HLA-A
HLA-B
HLA-C
What region is Class II genes located?
D region
Loci of D region
HLA-DP
HLA-DQ
HLA-DR
Class of MHC that codes for complement and cytokines
Class III
Both present in all nucleated cells and APCs
Class I
Primary functions of MHCs
- Graft rejection
- Tolerance induction (Discriminate self from non-self component)
- Activation of Adaptive Immunity
- Presentation of antigen
A marker/molecule in the surface of the cell that aid in the presentation of ANTIGEN, also determines the HISTOCOMPATIBILITY of transfusion/graft
Major Histocompatibility Complex
True or False. Class I molecules presents antigen to CD4+ cells
False. Class I - CD8+
Functions of Class I molecules:
- Tolerance induction to discriminate self from non-self especially during graft rejection
- Presentation of antigen
- Watchdogs of viral, tumor, and certain parasitic antigens
True or False. Class II molecules recognizes CD8+
False. Class II - CD4+
True or False. Class II are found in APCs only.
True.
Enumerate APCs
B lymphocytes
Macrophages
Dendritic Cells
Monocytes
This refers to selection/ discriminate self and non-self antigens during maturation of lymphocytes which cells act against or not against self antigens and Graft rejection
Tolerance Induction
Most highly polymorphic
HLA-DR
What complement proteins are coded by Class III genes?
C2
C4a, C4b
Factor B
True or False. Class III also codes for cytokines, like tumor necrosis factor (TNF)
True.
MHC Genes & Diseases.
B27
Ankylosing spondylitis
Reiter’s Disease
MHC Genes & Diseases.
HLA-DR3, HLA-DR4
Type I DM
MHC Genes & Diseases.
HLA-DR4
Rheumatoid arthritis
MHC Genes & Diseases.
HLA-DR5
Chronic Lymphatic Leukemia
Refers to a transplant or tissue or organ
GRAFT
True or False. For transfusion to be successful and not react, MHC molecules should NOT match between the donor and recipient (histocompatible)
False. For transfusion to be successful and not react, MHC molecules SHOULD MATCH between the donor and recipient (histocompatible)
Types of Transplantation
Autograft
Isograft
Allograft
Isograft/Autograft
Transfer of tissue/organs from one part of the body to another on the same person.
Graft between genetically different recipient and donor of the same species “Donor-Recipient’ (one person to another person)
Allograft
Graft between individuals of different species (e.g., pig heart valve to a human heart)
Xenograft
Organs which can be Transplanted (11)
blood vessels bone bone marrow cornea heart kidneys liver lung middle ear pancreas skin
True or False. • Graft rejection is primarily a T cell function, with some assistance from antibodies
True
Time required for Hyperacute rejection happens?
within MINUTES - HOURS
Hyperacute rejection is mediated by?
ANTIBODY MEDIATED
Where does Hyperacute rejection usually happens?
In o anti-A–related or anti-B–related antibodies to the ABO blood group systems
When does Acute Rejection happens after transplant?
weeks (7-21 days)
Mechanism of Acute Rejection
T-cell and APC mediated
How does acute rejection occur?
due to HLA incompatibility and the possibility of damage to antibody-coated cells through antibody-dependent, cell-mediated cytotoxicity (ADCC)
True or False. Chronic Rejection happens months (3 months) to years
True. Later than 3 months
Mechanism in Chronic rejection
Cell mediated
It results to a slow but continual loss of organ function over MONTHS or YEARS and disturbance of host-graft tolerance
Chronic Rejection
GVHD
Graft Versus Host Disease
Graft rejection based on the transfusion of • immunocompetent T lymphocytes from a donor to an immunodeficient recipient usually present in BONE MARROW transplant which the donor cells attacks all the cells of the host/recipient
GVHD
When does acute GVHD develops
First 3 months of transplantation
Process during transplant which it lowers the body’s immune system in order for the body not to immediately reject or directly interfere with the rejection response
Immunosuppression
Purpose of Immunosuppression
- Induction (intense immunosuppression in the initial days after transplantation)
- Maintenance of transplant
- Reversal of established rejection
Chain Structure - Class I
a chain
B2 microglobulin
Class I chain structure involve in the folding of a chaina
b2 microglobulin
3 domains of a chain
alpha 1
alpha 2
alpha 3
alpha chain domain that reacts with CD8+
alpha 3
alpha chain domain that binds to antigen for recognition
alpha 1
alpha 2
Most immunogenic organ
Bone Marrow
Least Immunogenic Organ
Cornea
Principle in HLA-Phenotyping
Complement dependent lymphocytotoxicity
Test in HLA Phenotyping
Microlymphocytotoxicity test
Vital dye usqed in HLA Phenotyping
Trypan Blue + Eosin Y
Positive result in HLA Phenotyping
(+) Dead Stained Cells
In HLA Phenotying, purifued T cells are used for ______________, and purified B cells are used for ______________.
In HLA Phenotying, purifued T cells are used for CLASS I TYPING, and purified B cells are used for CLASS II TYPING.
