Immuno I Flashcards
Antigen
anything that causes an immune response; “pathogens”
Antibody
immunoglobulin; protein molecule created by our immune system to target an antigen for destruction
-IgG, IgA, IgM, IgE, IgD
Cytokine
cell to cell communication proteins that control cell development, differentiation, and movement to a specific part of the body
What produces cytokines?
WBCs
Interleukins
13 cytokines that help regulate immune responses, inflammatory reactions, and hematopoiesis
IL-1 & IL-6
responsible for fever (pyritic response)
IL-6 type of response
acute phase response
Tumor necrosis factor (TNF)
activates neutrophils, mediates septic shock, causes tumor necrosis
Chemokines
type of cytokine released by injured cells that initiate an immune response and warn neighboring cells
Interferons (IFN)
block virus replication; can be used to treat diseases
Three subtypes of IFN
IFN-a, IFN-beta, IFN-gamma
Which IFN is the strongest?
IFN-gamma; produced by T cells; activates macrophages, NK cells, and neutros
Type I IFN
- alpha and beta
- function: induce viral resistance
- produced by almost any cell in the body
- can suppress T cell response and memory T cells in HIV
- may interfere with bactericidal mechanisms
Type II IFN
- gamma only
- secreted ONLY by NK cells and T lymphs
- Function: signals the immune system to respond to cancer or infectious agents
Two branches of the immune system:
Innate (fast)
Adaptive (slow)
Locations of hematopoiesis
Embryo/fetus: liver, spleen, thymus
Birth to adult: bone marrow
Characteristics of innate immunity
- fast
- immediate
- non-specific
- response does NOT increase with repeat exposure
Components of innate immunity
- physical barriers (skin, mucous membranes)
- Granulocytes (neutros, basos, eos, mast cells)
- Monocytes and macrophages
- Dendritic cells
- NK cells
- Complement cascade
1st step of innate immune system: Physical barriers (components)
- Skin (acidic sweat, fatty acids and enzymes)
- Mucous membranes (contain lysozymes against gram-pos bacteria, gastric secretions, acidic pH)
- Commensal bacterial
2nd step of innate immune system
inflammatory response
Physiologic results of the inflammatory response
- Vasodilation and leaky capillaries
- Decreased clotting
- Result in increased blood flow to the area
Steps of the inflammatory response (4)
1) Damaged tissues release histamine (increases blood flow)
2) Histamines cause capillaries to leak (releases phagocytes and clotting factors into damaged area)
3) Phagocytes engulf bacteria, dead cells, and cellular debris
4) Platelets move out of the capillary to seal wounded area
Adhesion molecules
membrane proteins that connect cells to other cells or the ECM; play a role in recruitment of neutrophils to wound
Results of chronic inflammation
Chronic cytokine release and WBC infiltration –> release of lysozyme and free radicals –> tissue damage
Basophils
- least common
- Allergic and helminth responses
- Release histamine and heparin
Eosinophils
- 1-6% of WBCs
- Circulate in bloodstream and present in organs (esp. GI and respiratory tract)
- Release H2O2, oxygen radicals, and leukotrines (lipid-signaling molecules that cause smooth muscle in airways to contract)
- Active in allergic reactions and asthma
- Stimulate T cells
- APCs
- Weakly phagocytic
Neutrophils
- Most abundant
- Fast first responders
- Esp. strong against bacteria and fungi
- Recruited by cytokines and release other cytokines to recruit macrophages and monocytes
- STRONGLY PHAGOCYTIC
- Produce NETs
Mast cells
- Release histamine and heparin
- Leave BM as immature cells and mature in tissues
- Present in “boundary” tissues b/w “inside” and “outside”
- MASSIVE RELEASE of histamine –> anaphylaxis
Monocytes
- agranular
- Half stored in spleen
- Half migrate to tissues and differentiate into DCs and macros
Functions of monos, macros, and dendros
- Phagocytosis
- APCs
- Cytokine production
Dendritic cells (DCs)
Strongest APC that activates helper T (T4) cells
-Capture antigens and migrate to LNs to present the antigen to T and B cells