1. Genetics of Immunity: Part 2

2. Major Histocompatibility Complex
MHC, a region that includes about 70 genes located on the short arm of chromosome 6
MHC genes encode the Human Leukocyte Antigens (HLAs) -- first studied white blood cells
Karyotype- photograph of human chromosomes, arranged in pairs

3. Human Leukocyte Antigens (HLAs)
A person’s HLA “type” identifies all of his or her cells as “self,” or belonging to the same individual → HLA Markers
An individual’s overall HLA type is based on 6 major genes
Vary genetically -- only 2 / 20,000 unrelated people match for the six genes by chance
Doctors match people for transplants by determining how alike the individuals are for these 6 genes
Usually 4/6 genes must match for a chance at successful transplantation

4. Antigen Presenting Cell
A macrophage (large, phagocytic cell) engulfs a bacterium & displays foreign bacterial antigens on macrophage surface → alerts other immune system cells
Helper T cells recognize antigens & bind to macrophage → start series of immune events

5. Human Immune System
Network of vessels (lymphatics) that transport lymph fluid to bean shaped structures around the body called _____________
- The spleen and thymus gland
Also make up the immune system
Lymph fluid carries white blood cells (_________________) specifically called lymphocytes. There are two major types of
lymphocytes → B cells and T cells

6. B Cells & T Cells Both made in the bone marrow:
B-cells mature in the bone marrow while T-cells travel through the bloodstream and mature at thymus gland
1) B-cells fight bacteria/viruses by making Y-shaped antibodies
2) T-cells: initiate cell mediated immunity (without need of antibiotics but rather with the use of white blood cells)

7. B Cells
After T cell finds a B cell match, it releases cytokines (cell signaling proteins) that stimulate the B cell to divide into 2 types:
Plasma Cells- antibody factories each secreting up to 2,000 antibodies/sec
2) Memory B Cells- fewer and usually dormant; respond to foreign pathogens faster on the secondary immune response

8. T Cells Three Types of T Cells:
Helper T-cells stimulate B-cells to make antibodies and help killer cells develop.
Killer/Cytotoxic T-cells directly kill cells that have already been infected by a foreign invader
Regulatory T-cells suppress immune response when no longer needed

9. Antibody Structure A Y-shaped sub unit that includes:
-Four Polypeptide Chains (2 heavy, 2 light joined by disulfide bond) with:
-Constant Regions- lower portion of each chain is a relatively generic amino acid sequence
-Variable Regions- upper portions have greater variability that help provide the specificity of antibodies to antigens
-Antigen Binding Sites- specialized ends of variable regions

10. Immune Response
Attacks pathogens, cancer cells, and transplanted cells with two lines of defense
Immediate, generalized innate immune response
More specific, slower adaptive (acquired) immune response
Start here genetics 1.

11. Innate Immunity Innate- existing in one from birth; native
-refers to basic resistance to disease that an individual is born with
1) Provides the first line of defense against invading pathogens until an adaptive immune response develops
2) present at all times
3) does not increase w/ repeated exposure
Examples: physiological barriers, inflammation, phagocytosis

12. Acquired/Adaptive Immunity
Immunity obtained from the development of antibodies in response to exposure to an antigen (vaccination) or an attack of an infectious disease
-From the transmission of antibodies from mother to fetus through the placenta
-Includes development of immunological memory, begins after 12hrs of an infection being present
Examples: chickenpox vaccine, polio vaccine, exposure to mononucleosis

14. Cytokines play a role in both innate and adaptive immunity
Interferons are cytokines that alert other parts of immune system of presence of infected cells
Interleukins are cytokines that cause fever, temporarily increasing body temperature that kills some bacteria and viruses
Tumor Necrosis Factors are cytokines that destroy bacterial toxins and attack cancer cells

15. Immune Responses
Humoral Immune Response- B cells produce antibodies after activation by T cells
Cellular Immune Response- T cells produce cytokines and activate other cells
Primary Immune Response- the response initiated after the first assault by a foreign pathogen
Secondary Immune Response- the second assault → activates immune system
“memory”
ex) why we only get some infections like chicken pox, once