Immunology Flashcards
What are the 3 lines of Defense?
- Barrier= Skin, swear, saliva, pH, lysozyme in tears
- Non-specific = grans, mast cell, NK cells, C’, Cytokines
- Adaptive = B cells, T cells, antibodies (5-6 days)
What are the primary lymphoid organs?
Bone marrow and thymus
B cells mature in BM
T cell mature in Thymus
What are secondary lymphoid organs?
Spleen and Lymphoids
Foreign antigens are transported here where mature lymphs wait to encounter antigen
What is Innate immunity?
Inborn
Non-adaptive
Non-specific
What cells in the blood are involved in innate immunity?
Monocytes Macros Neutrophils Eos NK cell
What is cellular defense mechanism in innate immunity?
Neutrophil or macrophage attach to bacterial cell wall receptor > ingest vacuoles called phagosome > phagosome fuses with lysosomes = phagolysosomes > bacteria is digested > products released
What cells in the tissues are part of innate immunity?
reticuloendothelial cells = monocytes in tissue Macrophages in lungs Kupffer cells in liver Microglial cells in the brain Osteoclast in the bone Histocytes in connective tissue Mast cells
What the functions of macrophages?
“Eating cell” - phagocyte foreign debris/microbes
Release cytokines - activates inflammation
Activate memory cells
APC - presents antigens on MCH II
Activated by pathogen or cytokines released by Tcell
Receptors for Fc, CR1, CR3, IL1, IL4
What are functions of dendritic cell?
Most potent phagocytic cell
Professional antigen presenting cell - presents to T cell
DC engulf antigen > migrate to spleen > finds T cell or B cell match
Only dendritic cell can activate naive T cell to induce primary immune response
What the functions of Neutrophils?
Primary job is phagocytosis - 1st to site of injury
50% in tissues and 50% peripheral blood
IL-8, IL-1, TNFa cause chemotaxis
Where is TNFa produced?
Produced by macrophages = activates inflammation
What is the function of Mast cell?
Highly phagocytic
Located in tissues
APC, allergy/hypersensitivity, anaphylaxis, inflammation
Self replacing and long life (9-18 months)
What is released in the granules of Mast cells?
15x more histamine than basophil Cytokines Serotonin heparin PAF thromboxane Prostaglandin Tryptase- potent vasodilator
What is the function of Basophils?
Release histamine
Allergy and hypersensitivity
How are mast cells and basophils activated?
B cells release IgE in response to allergen
Fc portion of TWO IgE binds to the Fc receptor on mast cells
If allergen is present it binds to both FAB sites of IgE and crosslinks them
What is the function of Eosinophil?
Degranluate outside of cell and functions to attack foreign substance
Fungi and parasites
What is the function of natural cell (NK) cells?
Defend against viral infected cells and tumor cells
Play a role in transplant rejection
Release IFNg and enhances own self
Large granular lymphs
What is the killing mechanism of NK cells?
Recognize missing self = low levels of MHC I
1. Pattern recognition receptors bind to pathogen
or
2. Fc receptors bind to Fc antibody (Antibody dep.)
Granules release > perforin punches hole and granzymes enter cell and kill
How does inflammation begin?
Macros, mast cells, NK cells, B cells, and dendritic cells
have pattern recognition receptors that recognize pathogen-associated molecular patterns (PAMP) and Disease-associated molecular patterns (DAMP)
Binding causes cytokines release`
What is the function of TNFa?
Principle mediator of acute inflammation
Stimulates endothelial cells > diapedesis of neutrophils and activates the coag pathway
Stimulates liver to produce Acute phase reactants
What is function of IL-1?
Works with TNFa
Formerly called endogenous pyrogen
stimulates T cells to produce IL-2 (IL-2 self stimulates T cells)
What is function of IL-6?
Get ARMY ready
Stimulates the liver to produce acute phase proteins
Activates NK cells
Proliferation of B cells and neutrophil production
What is function of IL-8?
Chemotaxis of Neutrophils and T cell activation
Mast cell growth
What is function of INF?
Mediates early response against viruses
Enhances NK activity
What is the inflammation process?
Cell injury is recognized by macro > cytokines released (histamine) > vasodilation > increased blood flow and capillary preamability > edema > neutrophils migrate >
What are the Acute Phase reaction proteins?
Produced by the liver
CRP = oposinization
Complement C3 = oposinization
Haptoglobin, Fibrinogen, Alpha-1-Antitrypsin, Ceruloplasmin
What is adaptive immunity?
Develops after exposure
Antigen specific
Memory of previous exposure
What is the function of T cells?
antibody like T cell receptors have a high affinity for 1 antigen
naive cells must be activated by an APC 1st
Activated T cells that bind antigen proliferate and become effector cells (Helper cells and cytotoxic cells)
Effector cells are only cells that can migrate to site of injury
Describe how T cells are selected for survival?
TCR that binds self transmits a survival signal
TCR that don’t recognize self or are overactive are removed
What is the function of B cells?
Differentiate into effector cells called plasma cells or memory B cells
What are antigen presenting cells?
Part of innate immunity but required for T cell activation
Dendritic cells, Mast cells, macros, and B cells
Engulf invader, digest, present antigen on MHC II to T cells
What MHC class do T helper cell recognize?
Recognize MHC II on APC
CD4 coreceptor on T cells locks TCR/antigen/MHC II complex in place
What MHC class do cytotoxic cell recognize?
Recognize MHC I on any cell in body
CD8 coreceptor binds TCR/antigen/MHC I and locks in place
What cells are Class I MHC molecules located on?
Present on all cell in body
What cells are Class II MHC molecules located on?
Only on antigen presenting cells
Describe the structure of MHC I molecules
1 alpha heavy chain with 3 domains (a1, a2, a3)
light beta-2-microglobulin - stabilizing protein
Alpha-1 and Alpha-2 are variable regions
Alpha-3 is constant
Describe the structure of MHC II molecules
1 alpha chain with 2 domains
1 beta chain with 2 domains
Alpha 1 and Beta 1 are variable regions
What is the function of T helper cells?
CD4 + cells recognize antigen presented on MHC II
Proliferate and produce cytokines that activate B cell and cytotoxic T cells
What is the function of Type 1 T helper cells?
Strong inflammatory response
Fights intracellular pathogens
Activates Cytotoxic cells
What is the function of Type 2 T helper cells?
Strong antibody response Activated by B cells Fights extracellular pathogens Promotes B cell antibody class switching Promotes B cell IgE production - Allergic response
What is the function of Type 17 T helper cells?
Fights extracellular bacteria and fungi at mucosal surface
Part of delayed type hypersensitivity reactions
Inhibit T regulatory cells = Promote auto immune RXN
What is the function of Regulatory Cells?
Formerly called T suppressor cells
Tolerance of self by down regulating Cytotoxic cells
Prevents autoimmune disease, but in chronic illness, Treg are down regulated so auto immune risk increased
What is the function of Cytotoxic T cells?
CD8 + and recognize antigens on MHC I molecules
Similar to NK cells - Destroy Viral or tumor infected cell
Tc inspect cells and recognized foreign cells
Uses Perforin and granzymes to kill
What are the charateristics of B cells?
B cells develop in fetal liver and in the BM in adults
Produce antibodies, present antigens, and memory cell
Have b cell receptor, CR1, sIgM and sIgD
What is function of sIG?
Surface Immunoglobulins are attached to B cells and allows B cell to detect specific antigen
Each B cell has sIgM and sIgD that are specific for a single antigen
What is the T cell dependent B cell activation?
- Antigen binds to sIg on B cell > internalized > presented on MHC II molecule
- A T cell is activated 1st. T helper cell binds to MHC II on B cell and releases cytokines
IL-2 is main cytokine that activates B cells > clonal expansion > plasma cell differentiation
What is the cell independent B cell activation?
- Antigen binds to sIg on B cell
- A few types of antigens can directly activate B cell such as bacterial cell components. Antigen binds to pathogen recognition receptor on B cell
This pathway is not as effective
What is the function of plasma cells?
No surface immunoglobulins
Just produces antibody of single specifitiy
How are B cell selected for survival?
B cell receptors are formed through random gene rearrangement. Some will react to self causing auto-immune disease, these cell will signal cell apoptosis
10-20% of B cells will survive
What is CD3 found on?
All T cells
Related to T cell receptor
What is CD4 found on?
T helper cells
What is CD8 found on?
Cytotoxic T cells
What is CD19 found on?
B cells
what is CD34 found on?
Stem cells
What is CD55?
DAF
Carries Cromer blood group antigens
What is the E-rosette test?
Enumerates T cells
T cells are incubate with sheeps RBC’s and form a rosette pattern with CD2 marker
What is ouchterlony testing?
Technique used identify antibodies or antigens. When lines cross = non-identity
What is Severe Combined Immunodeficiency?
Failure to develop lymphoid precursor cells = no T, B, or NK cells
What is Burtons A-gammaglobulinemia?
Pre B cells do not mature
Lack of all Ig subclass
What is selective IgA deficient?
No serum or sercretory IgA.
Can form anti-IgA
What is Thymic hypoplasia?
Failure of Thymus and parathyroids to develope
What is Nezelofs syndrome?
Abnormal thymus - T cell dysfunction
Which Cytokine increases NK activity?
IFN produced by T cells and NK cells
CR is found on what cells?
RBC’s, PLT’s, Macros, Neutrophils
IL-1 is produced by what cells?
Macrophages > stimulates T helper cells
What is gene rearrangement?
genes combine their varible segments to create a huge number of B cells with specific target for different epitopes
