Immunology Basics Flashcards
White blood cells from bone marrow
- Granulocytes (5 types)
- Monocytes -> mature to macrophages
White blood cells from lymph tissue
Lymphocytes
Type of granulocytes
- Neutrophils
- Eosinophils
- Basophils
- Monocytes
- Mast cells
Megakaryocyte
- Non-leukocytes
- Make platelets
Erythrocyte
- Non-leukocytes
- Red blood cell
Innate immunity
- Common across persons unless on drugs
- Neutrophils
- Tissue macrophages
Acquired immunity
- Unique to each person
- Lymphocytes (T & B)
Phagocytosis power of neutrophils
5-20 bacteria
Phagocytosis power of tissue macrophages
100 bacteria
Macrophage
- Killer
- Phagocytosis and activation of bactericidal mechanisms
- Antigen presentation
Neutrophil
- Killer
- Phagocytosis and activation of bactericidal mechanisms
Eosinophil
- Killer
- Killing of anti-body coated parasites
Basophil
- Caller
- Recruited following allergic reaction
- Releases heparin and histamine
- Least common granulocyte
Mast cell
- Caller
- Release of granules containing histamine and other active agents
Anti-histamines reduce release of what cell
Mast cells
Inflammatory response
- Vasodilation
- Increase capillary permeability & leakage into interstitial space (space between cells)
- Increased migration of granulocytes & monocytes (macrophages)
- Swelling (caused by histamine, prostaglandins, chemokines)
Waste products including CO2 & metabolites stimulate
Sialyl-Lewis bodies
Attach to Sialyl-Lewis body
L-selectin on neutrophils (1st responders)
On cell membranes of capillaries that halt the neutrophils
E-selectin
Diapedesis
Squeezing of neutrophils through capillary membrane
1st line of defense
Tissue macrophages (minutes) already residing in tissue
2nd line of defense
Invasion of neutrophils (1 hour)
3rd line of defense
2nd invasion of macrophages which were called by dendritic cells (8 hours)
4th line of defense
Increased granulocyte and monocyte production in bone marrow (3-4 days)
- Does not occur every time, depending on on level of infection
Dendritic cells
- The link between innate and acquired immunity
- Reside in peripheral tissues
- Takes piece of bacteria & migrates via afferent lymphatics to regional lymph nodes to present to acquired immune system (B & T lymphocytes)
MHC class I molecule
On ‘you’ cells = no attack
Ubiquitous molecule
On you and anyone, without presence of MHC class I, natural killer cells will destroy via poking hole in cell membrane
B lymphocytes
- Humoral/antibody mediated immunity
- Antibodies circulating in serum
- Primary defense against extracellular pathogens: extracellular bacteria, circulating virus
T lymphocytes
- Cell-mediated immunity
- Direct cell to cell contact or secreted soluble products ie. cytokines
- Primary defense against intracellular pathogens: viruses and fungi, intracellular bacteria, tumor antigens and graft rejection
MHC class 1 molecules present antigens to…
Cytotoxic T cells
MHC class 2
Expressed on antigen-presenting cells (dendritic cells, B-cells, and macrophages)
-Signal to not destroy
Activation of B cells to make antibody
Dendritic cell presents antigen to B cell -> MHC class 2 & processed antigen displayed on B cell -> lymphokines & activated helper T cell work to change B cell into plasma cell -> plasma cell releases antibodies
Variable portion of antibody
Antibody sits on top of this portion and takes shape of foreign invader -> will mark for neutrophils & macrophages for phagocytosis
Membrane attack complex (MAC)
Forms pore spilling insides of invader (lysis)
Complement system/pathway
- Involves antigen-antibody complex
- Antibodies bind and change forms
- Promotes inflammatory response (increased chemotaxis) from mast cells and basophils
- Lysis of invading cell via MAC
- Opsonization and phagocytosis by neutrophils
Alternative pathway
- Does not require antibodies
- Uses C3 which is normally in the plasma and comes from B cells (considered innate immunity)
- C3 directly activated by carbohydrates on pathogen cell surface
- C3 can go in 3 directions -> 2 killers & 1 caller
Helper T-cells (CD4+)
- Most numerous
- Produce and secrete lymphokines (interleukins and interferons)
- MHC 2 molecules
- These are lost in AIDS
Cytotoxic T-cells (CD8+)
- Bind and punch holes (lyse) in bacteria with perforins and granymes
- MHC class 1 molecules
- Similar to natural killer cells
Regulatory T-cells (Treg)
- Suppressor T cell
- Regulator, limits ability of immune system to attack body’s own tissue - prevents autoimmunity
- Important for end of immune response
- Produce anti-inflammatory cytokines
- Kill activated immune cells
- Alter dendritic cell behavior so they can’t activate T cells
