Lecture 17 Flashcards
How many major HLA genes are needed for most transplants to succeed?
4
HLA genes
account for about 50% of the genetic impact on immunity
what determines an HLA type
several genes with multiple alleles
Major histocompatibilty complex
MHC region on short arm of chromosome 6 containing about 70 genes
what encodes human leukocyte antigens (hla)
MHC class I and II
what is the difference between class I and II HLAs that encode human leukocyte antigens?
Class I - encode antigens defining “self”
Class II - encodes several proteins found in antigen-presenting cells
MHC class III genes
encode protein providing non-specific immune functions
the human immune system
a network of vessels called lymphatics and bean-shaped structures called lymph notes
what is lymph and what does it carry
the fluid filling the lyph ducts
-carries macrhopages and B- and T- lymphocytes
what organs are involved in production or maturation of immune cells
spleen and thymus
bone marrow
immunity
the immune response attacks pathogens, cancer cells and transplanted cells with two lines of defense
1) innate immunity
2) adaptive immunity
difference between innate and adaptive immunity
- innate immunity - immediate and generalized
- adaptive immunity - specific and slower
these act after various physical barriers block pathogens
physical barriers
The first line of defense Examples include: - Unbroken skin - Mucous membranes and secretions - Waving cilia of the respiratory tract - Flushing effect of tears, saliva, urination, and diarrhea All of these are non-specific defenses
a central part of innate immune response - inflammation
- A process that creates a hostile
environment for pathogens - Sends in phagocytes that engulf and destroy pathogens via phagocytosis
innate immune response
OInflammation Collectins - Recognize specific bacterial antigens Cytokines - Interferon = Anti-viral - Interleukins = Fever-inducing - Tumor necrosis factor α = Anticancer
Cytokines also play a role in adaptive immunity
what immunity do cytokine play a role in?
adaptive and innate immunity
complement system (innate immune response)
- Plasma proteins that assist or complement other defense responses - Roles of complement proteins include: Puncture bacterial cells Dismantle viruses Trigger histamine release to dilate blood vessels Attract phagocytes
adaptive immunity
Requires stimulation
Response time is in days
Has three basic characteristics:
1) Diversity: many different pathogens
recognized.
2) Specificity: distinguishes particular molecules.
3) Memory: responds faster with
subsequent exposure.
- Primary immune response: reaction to first exposure.
- Secondary immune response: reaction to exposure using “memory” of first response.
adaptive immunity - two types of response
1)Humoral immune response
- B cells produce antibodies in
response to activation by T cells
2)Cellular immune response
- T cells produce cytokines and
activate other cells
cytokines
- Interferon = Anti-viral
- Interleukins = Fever-inducing
- Tumor necrosis factor α = Anticancer
humoral immune response
- Antigen-presenting macrophage activates a helper T cell
- Helper T cell activates a B cell with matching cell surface receptors
- B cells divide to produce plasma cells and memory cells
- Plasma cells secrete antibodies into blood that will recognize the antigen presented.
- Memory cells remain dormant until second exposure when they respond faster and more effectively
humoral immune response - polylonal
polyclonal
-different antibody proteins recognize and bind to different features of foreign cells
antibody structure
Minimally consist of four polypeptide chains
- Two long (heavy) chains
- Two shorter (light) chains
- Constant region of each chain is similar
- Variable region of each chain is diverse
Antigen binding sites
- Idiotypes: sites in direct contact with antigen
- Epitope: portion of the antigen contacting the antibody
