Rhinology Immunology Flashcards
What are the two major types of immunity?
● Innate (nonspecific): First line of defense; antigen
independent, immediate maximal response, no immu-
nologic memory
● Adaptive (specific immunity): Antigen dependent, delayed
maximal response, immunologic memory, lymphocytes
and lymphocyte-derived immunity
What are the three major components of innate
(nonspecific) immunity?
● Anatomical boundaries: Epithelium; mechanical move-
ment and trapping from cilia, tears, saliva, and mucus;
competition from normal flora
● Humoral barrier: Cytokine system, complement system,
coagulation; fatty acids, lysozyme, lactoferrin, transferrin,
phospholipase, defensins, surfactants, IL-1, TNF-α, inter-
ferons (IFNs)
● Cellular barrier: Polymorphonuclear cells, macrophages,
NK cells, and eosinophils
In what type of immunity do toll-like receptors
coordinate the responses of cytokine-complement-
phagocytic responses?
Innate (nonspecific) immunity
How do NK cells differ from NK T cells?
They are part of the innate immune system but can
participate in the adaptive immune response. They arise
from the lymphoid progenitor cell, which gives rise to T and
B cells, do not have common T cell–specific markers (CD3,
TCR, MHC, etc), they express CD-16, CD-56, and often CD8.
They can be activated by IFN to target virally infected or
tumor formation within 3 days based on the absence of
“self” markers.
The anti-tumor effect of NK cells is thought to be
due to their unique ability to recognize what?
The absence of self. Although T cells and many other immune
effector cells are programmed to recognize nonself proteins
produced by viruses or bacteria, NK cells have the ability to
recognize when self peptides and proteins have been
downregulated as a result of tumor transformation or what
might be seen with viral infections. The most commonly
encountered down regulated self molecule that might be
“recognized” by NK cells are MHC molecules.
The adaptive immune system reacts specifically to
individual antigens (proteins, polysaccharides, or
macromolecules). What is the region of the
antigen that is recognized by antigen-specifc
receptors (T and B cells) and immunoglobulins
within the adaptive immune system called?
Epitope (determinant)
What is the term that defines the ability of a host to ignore self and demonstrate immunologic unre-
sponsiveness to self for both innate and adaptive immune responses?
Tolerance
Name the two subtypes of adaptive immunity.
● Humoral immunity → B cells, antibodies
● Cell-mediated → T cells, cytokines
Describe the three basic steps of adaptive
immunity.
● Recognition of antigen
● Lymphocyte activation → production of cytokines,
cytokine receptors, and other proteins; clonal expansion
of lymphocytes; cellular differentiation (i.e., B cell into
plasma cell)
● Removal of the offending antigen (clearance)
What are the primary lymphoid organs?
● Thymus
● Bone marrow
What are the secondary lymphoid organs, and
what is their purpose?
● Systemic (spleen and lymph nodes)
● Mucosal immune system (tonsils, Peyer patches, intra-
epithelial lymphocytes, lamina propria of mucosal tissues)
● Cutaneous immune system
Where do myeloid (erythrocytes, neutrophils,
platelets, basophils, eosinophils, monocytes/macro-
phages, and dendritic cells) and lymphoid cells (T cells, B cells, NK cells, plasma cells) arise from?
Bone marrow
Name the immature dendritic cell found in the
skin and mucosa that contains Birbeck granules, is
most prominent in the stratum spinosum of the
skin, and is involved in antigen processing.
Langerhans cells
Name the specialized mucosal immune cell that is
responsible for transocytosis (pinocytosis) of
antigens across the follicular epithelium to
germinal centers within Peyer patches within
tonsillar tissue.
M (microfold) cells
Immune responses to hematogenous antigens
and encapsulated organisms occur predominantly
in the spleen, where lymphoid follicles surround
small arterioles forming what structure?
Periarteriolar lymphoid sheaths
Lymphocytes can be identified by what specialized
molecules on their surface that can help other
cells (and researchers/clinicians) recognize their
level of maturity, lineage, and extent of immune
activation?
Cluster of differentiation (CD) markers
Name the cell associated with the following CD markers: ● CD2 ● CD3 ● CD4 ● CD8 ● CD25
● All T cells ● All T cells ● TH1 or TH2 cells ● T-suppressor cells (cytotoxic T cells) ● + CD4 = TH17 or T regulatory cells
What cell is required to undergo maturation in
the thymus, and what are the possible outcomes
of differentiation?
T cells differentiate in the thymus via both positive and negative differentiation: ● Apoptosis ● CD4 + helper T cell ● CD8 + precytotoxic T cell
What percentage of CD4 + and CD8 + T cells
survive selection in the thymus?
Less than 5%; most say 2% or less
Where does negative selection of developing
T cells occur?
Thymic medulla
The process by which developing T cells that react
too strongly with self peptides are deleted is called
what?
Negative selection
What is the process called by which developing
T cells that react appropriately with self peptides
are signaled to survive and continue to develop?
Positive selection
What cell type is stimulated to develop from naïve
CD4 cells (TH0) by intracellular pathogens and IL12
and subsequently inhibits B cells, produces INF-γ
and IL2, and stimulates cell-mediated immunity
(activates cytotoxic CD8 cells, etc)?
TH1 cells
What cell type is stimulated to develop from naïve CD4 cells (TH0) by allergens and IL-4 and subse-
quently recruits/activates eosinophils, activates B cells; produces IL-4, IL-5, IL-6, IL-10, and IL-13;
and is involved in both allergic disease and humoral
immunity?
TH2 cells
How does the immunologic T-cell response to oral antigens differ compared with more systemic re-
sponses?
Oral antigens are more likely to induce T-cell anergy or T-
cell tolerance than T-cell activation.
What are the two types of MHC molecules?
● MHC Class I: Display self and nonself antigens (8–10
amino acids), membrane associated glycoprotein.
● MHC Class II: Display extracellular proteins (various length,
generally longer, 18 to 20 amino acids) that are phag-
ocytosed and processed intracellularly before presentation
What type of MHC molecules are expressed by
almost all nucleated cells and when downregulated
can result in targeted destruction by NK cells and
present endogenous antigen?
MHC class I
What type of MHC molecules are expressed primarily on antigen-presenting cells and lympho-
cytes (B cells, macrophages, endothelial cells, or dendritic cells primarily) and present processed
exogenous antigen?
MHC class II
What type of T cell recognizes antigen presented by MHC class II molecules?
TH cells (CD4 +)
What type of T cell recognizes antigen presented by MHC class I molecules and kills cells presenting that antigen?
Cytotoxic T cells (CD8 +)
What are the components of MHC molecules?
● Extracellular peptide binding region
● Pair of Ig-like domains (bind CD4 and CD8)
● Transmembrane region
● Cytoplasmic tail
To activate TH cells, antigen-presenting cells must present antigen via an MHC class II molecule, as well as secrete which important cell signal?
IL-1
Which cells secrete antibodies, and how are they
activated?
B cells phagocytose antigen and present it to TH cells via
MHC class II molecules. T-cell then stimulates the B cell via
IL-2 and IL-4 to mature into an Ig-producing plasma cell.
Alternatively, large antigens can crosslink enough B-cell
receptors to lead to direct activation of the cells and
antibody production.
What cell type can be identified by the CD
markers 19 and 21?
B cells