Adaptive Immune System - Diebel Flashcards
Humoral Immunity
B-cells that protect extracellular spaces release antibodies into bodily fluids.
Cell-Mediated Immunity
T-cells that survey surfaces of cells, looking for mutated cells or parasites.
What types of cells come from Lymphoid Progenitor cells?
NK Cells
Dendritic Cells
B-Cell Progenitor
T-Cell Progenitor
B-Cell Progenitors can produce…
Mature B-Cells –> Plasma Cells and Memory B-Cells
T-Cell Progenitors can produce…
CD8+ T-Cells and CD4+ T-Cells
What are the two kinds of cells in adaptive immunity?
Antigen Presenting Cells that phagocytose PAMPs and DAMPs to present them to lymphocytes
Lymphocytes that recognize antigens
When a epitope binds to a lymphocyte’s receptor, like a lock-and-key, then the lymphocyte produces _________ to recruit macrophages and neutrophils.
IFN-gamma
The adaptive immune response must be ________. Only a few T and B lymphocytes will recognize any given antigenic sequence.
Induced
MHC Class I
Antigens synthesized within cells that are recognized by CD8+ killer T-cells and expressed on all cells except RBCs.
MHC Class II
Antigens produced via phagocytosis that are recognized by CD4+ helper T-cells and expressed on monocytes, macrophages, dendritic cells, B-cells, and epithelium of thymus.
MHC Molecules are also known as…
HLA - Human Leukocyte Antigens
Primary Lymphoid Organs
Thymus and Bone Marrow
Secondary Lymphoid Organs
Waldeyer's Ring (Tonsils and Adenoids) Bronchus-Associated Lymphoid Tissue Lymphoid Nodules Peyer's Patch Urogenital Lymphoid Tissue Spleen
Define Lymphokines
Locally released, short-range mediators that are released by activated T-Cells to attract monocytes and macrophages
M1 “Angry” Macrophages release?
IFN-gamma
What do all T-Cells express?
CD3/TCRs
What are the two types of T-Cell Receptors?
Alpha-Beta with CD3
Gamma-Delta with CD3
In what way are Alpha-Beta T-cells able to function?
Binding to MHC I or MHC II molecules
What do Gamma-Delta T-cells protect?
mucosal surfaces
What makes Gamma-Delta T-cells special?
Do not require MHC complex
What are circulating gamma-delta T-cells classified as?
Double Negative T-Cells (CD4- and CD8-)
Type 1 Helper T-Cells (Th1)
Recognize antigen and make lymphokine to attract M1 macrophages to attack a serious infection.
Th17 Helper T-Cells
Focused on inflammation; more powerful than Th1; cause severe autoimmunity through IL-17
Type 2 Helper T-Cells (Th2)
“Alternatively Activates” M2 ‘Healing’ macrophages to wall-off parasites/pathogens and promote healing after a pathogen-killing Th1 response.
Follicular Helper T-Cells (Tfh)
Stimulated by antigen to migrate from T-Cell areas of lymph nodes into the B-Cell follicles, where B-Cells can get activated
Regulatory T-Cells (Treg)
Makes cytokines that suppress activation and funtion of Th1, Th17 and Th2; the check-and-balance of the immune system.
What is the main cytokine that Treg cells make?
IL-10
Describe IPEX
Regulatory T-Cells are not working properly to turn off the immune response
Cytotoxic/Killer T-Cells (CTL)
Destroy any body cell that bears a foreign or abnormal antigen on its surface and recognizes antigen complexed with MHC I
Th1, Th2, Th17, Tfh, and Treg have a molecular marker, which one?
CD4
APCs release what cytokines?
TNF-alpha and IL-1
Describe the activation of T-Cells (remember it is a two hit system: needs two interactions in order to activate)
T-cell Receptor recognizes HLA (MHC) bound antigen, with CD4/8
B7-1 (CD80) or B7-2 (CD86) on APC binds to T-Cell CD28
CD2 binds to what?
LFA-3 (CD58)
ICAM binds to what?
LFA-1
TCR binds to what?
MHCI or MHCII
B7-1 (CD80) or B7-2 (CD86) binds to what?
CD28
CD4 binds to what?
MHCII
CD8 binds to what?
MHCI
Type I Hypersensitivity
Too much IgE production in response to environmental antigen leading to mast cell and basophil release of histamine, causing synthesis of prostaglandins and leukotreines, such as hay fever and asthma.
Type II Hypersensitivity
Autoimmunity due to antibodies that react against self, such as hemolytic disease of maternal antibodies reacting to fetal RBCs, Myasthenia Gravis (AChR antibodies), and Good Pasture’s Syndrome (Basement membrane antibodies causing nephritis).
Type III Hypersensitivity
Immune complexes of antigen and antibody that get stuck in small vessels, such as the kidneys, joints, pleura and skin. Complement is activated to respond to the antigen-antibody complex and healthy tissues are destroyed in the process, which happens in Lupus (making antibody to own DNA) and RA (making antibody to antibody).
Type IV Hypersensitivity
Cell-mediated hypersensitivity caused by activated CD4+ T-Cells (autoimune or innocent bystander injury); Contact hypersensitivity, TB reactions, Granulomatous hypersensitivity
X-linked Agammaglobulinemia
Absence of B-lymphocytes
CD40 Ligand Deficiency
Failure of Ig class switching in B-cells
Activation-Induced Cytidine Deaminase Deficiency
Failure of Ig class switching in B-cells
Common Variable Immunodeficiency
Failure to produce antibodies to particular antigens
Omenn Syndrome
VDJ recombination Failure - cannot produce TCRs or BCRs
X-linked Severe Combined Immunodeficiency
Failure to produce mature T-lymphocytes
DiGeorge Syndrome
Failure of the Thymus to develop correctly
Hemophagocytic Lymphohistiocytosis
Failure of CD8+ T-cells and NK cells to produce or release lytic granules
IPEX
Failure of peripheral tolerance due to defective regulatory T-cells (Can’t turn off the immune response)
What types of cells have no Output Signals?
Eosinophils and Basophils
What is the Neutrophil Output Signal and to what cell types?
TNF-alpha to T-cells and Macrophages
Name the two general activators of T-Cells.
IL-2 and IL-15
What cytokines differentiate T helper cells to Th1 helper cells?
IL-12 and IFN-gamma
What cytokine differentiate T helper cells to T2 helper cells?
IL-4
What cytokines down-regulate Th1 helper cells?
IL-10 and TGF-Beta
What cytokine down-regulates T2 helper cells?
TGF-Beta
What type of cell and receptor presents antigen to CD4+ Helper T-Cells in the lymph node or spleen?
Dendritic Cells on MHC II
What cell types express MHC I?
All cells of the body except RBCs
Why would it be better for the immune system to kill an infected cell than to let the virus kill it?
An infected viral cell has the potential to produce 100-1000s of viral particles during the cell death process. By making the cell commit apoptosis, then the virus can’t replicate.
How is killing facilitated by CD8+ cytotoxic T-Cells?
FAS presented on a target cell binds to FAS ligand on the T-cell to induce caspase activation and apoptosis
What cytokines can be released by CD8+ T-Cells?
TNF, Perforin, and Granzymes
Describe Positive Selection of T-Cells in the Thymus.
T-cells must recognize MHC Class I or MHC Class II molecules (Self-Restriction)
CD4 T-Cell recognizes MHC II
CD8 T-Cell recognizes MHC I
Describe Negative Selection of T-Cells in the Thymus.
T-cells that recognize self-antigens bound to MHC II are killed (T-cells need to be tolerant to self-antigens)
What lymphocyte markers do T-Cells express?
All express CD3 (part of TCR)
Some express CD4
Some express CD8
What lymphocyte markers do B -Cells express?
CD40 (BCR), CD79a and CD79b
No need for MHC recognition!
IgG
Two adjacent IgG molecules form a hexamer of IgG to activate complement
Passes through placenta
Replaces IgM after a week or two.
IgM
Polymeric immunoglobulin even better at activating complement than IgG and first antibody type to appear after new pathogen exposure.
IgM secreted from a B-cell is in a pentamer form.
IgD
Main antibody inserted in B-cell membranes as an antigen receptor
IgA
Antibody in the secretions associated with Secretory Component (allows IgA to cross through the epithelial cells into the mucosal layer)
Secretory component makes IgA resistant to digestive enzymes, as it is the first line of defense in mucous membranes.
IgE
Attach to mast cells and when bound to antigen, will cause the mast cell to produce prostaglandins, leukotrienes, and cytokines and release granules of histamine.
Provides resistance to hemalinths
Describe the pathway of immunity to disease.
- When an antigen penetrates the mucous membranes, it can encounter T and B cells that produce IgA and sometimes IgE.
- IgA is secreted to establish local immunity.
- If the antigen reaches local lymph nodes or spleen, IgM will be produced first, followed by IgG.