|11||MHC and Antigen presentation|
Study guide for exam 1 Edit
Lecture 1: Introduction to ImmunologyEdit
- Skin’s natural barriers to infection
- Contiguous surface with tight junctions
- Stratified squamous epithelium binds and sheds potential pathogens
- High salt concentration in sweat
- Lower temperature on skin surface
- Antimicrobial sebum from sebaceous (oil) glands in hair follicles
- Commensal (nonpathogenic) bacteria are “placeholders” on skin surface
- Antigen presenting cells (innate immune system)
- Primary lymphoid organs
- Bone marrow - produces red cells, white cells, and platelets (and other cells)
- Thymus - "schools" immature T cells from bone marrow to:
- Recognize foreign particles with high affinity (positive selection)
- Not respond to self-particles (negative
- Secondary lymphoid organs
- Lymph nodes
- Gut-associated, mucosal-associated and bronchiolar-associated lymphoid tissue (GALT, MALT, BALT)
- Innate Immunity
- Cells that do not need prior activation in order to recognize pathogens
- Respond rapidly to infection
- Primarily phagocytic
- No memory
- Activate adaptive immune response
- Adaptive (acquired) immunity
- Antigen-specific, needs prior activation
- Responds more slowly
- Has memory to fight off future infection more quickly and effectively
- Natural Passive immunity - Mother transferring maternal antibodies to a child via breast feeding
- Artificial Active immunity - Immunizations
- Natural Active immunity - Exposure to an infectious agent
- Artificial Passive immunity - Injection of live antibodies
Lecture 2 Cells of the Immune systemsEdit
These cells look like fried eggs and line blood vessels; when injured they secrete prostaglandins that cause vasodilation and pain, and adhesion molecules which help with innate immune cell diapedesis.
Cytoplasmic fragments of megakaryocytes in bone marrow. These are involved in clotting following and endothelial cell injury.
Innate immune cells that release histamine and serotonin for vasodilation and acute inflammation. These also can be phagocytic and function as APCs.
Granulocytes with multilobed nuclei. Their granules contain reactive oxygen species. Neutrophils (also known as polymorphonuclear cells) are involved in phagocytosis and the innate immune response
Granulocytes with multilobed nuclei. Their granules stain orange-red with Eosin (acidic dye). They are involved in allergy and parasitic infections
Granuloctyes with multilobed nuclei. Their granules stain dark purple with hematoxylin. They are involved in allergy and parasitic infections.
Natural Killer CellsEdit
These cells look like lymphocytes but have slightly more cytoplasm. They are in the innate immune system unlike other lymphocytes. They recognized PAMPs with TLRs and kill pathogens with perforin and granzyme.
These are larger than neutrophils, have a kidney bean shaped nucleus and have abundant blue cytoplasm. They are professional phagocytes and antigen presenting cells. They are monocytes in the blood and macrophages in the tissue. Macorphages multiply in tissues and secrete cytokines to upregulate adaptive immunity.
T and B lymphocytesEdit
These are small cells that are mostly nucleus with scant, deep blue cytoplasm. There are 755 T cells int he blood. They produce cytokines, kill, and activate adaptive immunity. B cells differentiate into plasma cells once activated and produce antibodies. Cytotoxic T cells (Tc cells) use perforin and granzyme to kill.
Spindloid cells that secrete collagen and ground substance. They first secrete type III collagen, then type I collagen. They are important at the end of inflammation and involved in wound healing.
Lecture 3: Organs of the Immune SystemEdit
Primary Lymphoid OrgansEdit
Bone marrow is one of two primary lymphoid organs. Its primary purpose is to make hematopoietic cells and school B cells in positive and negative selection. During acute inflammation the bone marrow increases production of neutrophils followed by monocytes and lymphocytes. This helps keep up with the demand of the infection/inflammation.
The thymus' primary purpose is to school immature T cells. Naive T cells that enter the Thymus to be schooled must go through postive and negative selection. For positive selection the T cell must be able to bind antigens with high affinity. For negative selection it must not respond to self proteins. T cells that fail schooling die by apoptosis. T cells that pass school travel to secondary lymphoid organs to circulate in the blood.
Autoimmunity results when T cells that fail negative selection are allowed to leave the thymus.
Secondary Lymphoid OrgansEdit
Adenoids are Pharyngeal or nasopharyngeal tonsils. If they become enlarged they can obstruct the nasal passages and disrupt breathing. Surgery (Adenoidectomy) may be needed to remove the adenoids if this occurs.
These are located in the oropharynx and sample pathogens coming in through the nose and mouth. Tonsils have crypts and contain mainly lymphocytes and macrophages. Tonsilitis occurs with increased macrophages or neutrophils. This may require antibiotic or surgical therapy. Tonsils are comprised of stratified squamous epithelium (vs. the ciliated respiratory epithelium of the adenoids) because of traume caused by food passing the tonsils.