INNATE AND ADAPTIVE IMMUNITY Flashcards
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PRIMARY LYMPHOID ORGANS
Bone marrow
Thymus
SECONDARY LYMPHOID ORGANS
Spleen
Lymph nodes
Mucosal-associated lymphoid tissues (MALT)
Cutaneous-associated lymphoid tissue (CALT)
maturation of B lymphocytes and NK cells
Bone marrow
maturation of T lymphocytes
Thymus
One of the largest tissues in the body
bone marrow
function of bone marrow
source of hematopoietic stem cells
B cells is named after
bursa of Fabricius in birds
Immature T cells appear as early as
8 weeks in gestation
Site of T-cell maturation and
differentiation
thymus
Largest secondary lymphoid organ, Acts as a large discriminating filter, Removes old and damaged cells and
foreign antigens from the blood
spleen
Makes up over half the spleen’s volume
Destroys old and damaged red blood cells
red pulp
Only 20% of the spleen’s total weight
Contains lymphoid tissue arranged around
arterioles in the periarteriolar lymphoid sheath
(PALS)
PALS contains mainly T cells
White Pulp
Central collecting points for lymph fluid from adjacent tissues
Filtration of interstitial fluid allows contact between lymphocytes and foreign antigens
lymph nodes
Filtrate of blood from water and lowmolecular-weight solutes
Lymph fluid
Mucosal-Associated Lymphoid Tissues
Tonsils
Appendix
Peyer’s patches
small masses of macrophage lining oral and pharyngeal cavities
Tonsils
near the junction of the small intestine and the large intestine and has abundant infection-fighting lymphoid cells
Appendix
specialized type of MALT located at the lower ileum of the intestinal tract
Peyer’s patches
Resistance through normally
present body functions, nonspecific, and no prior exposure required
INNATE (NATURAL) IMMUNITY
Specific resistance for each
pathogen
Memory and specificity, increased
response upon repeated exposure
ADAPTIVE IMMUNITY
what line of defense does innate immunity belong
first and second line of defense
what line of defense does adaptive immunity belong
third line of defense
components of innate immunity
External Defense System
Internal Defense System
Anatomical barriers (e.g., skin, mucous membranes) that prevent pathogen entry.
External Defense System
Activated if external barriers are breached; includes cellular responses and phagocytosis.
Internal Defense System
external defense systems
Physical
Chemical
Biological
chemicals in:
skin
respiratory tract
stomach
vagina
found in tears and saliva
lactic acid, fatty acids, psoriasin
mucus, cilia
gastric acid, hydrochloric acid
lactic acid
lysozyme
physical barriers in unbroken skin
epidermis
dermis
Consists of tightly packed epithelial cells coated with keratin, making it impermeable to most infectious agents.
Epidermis
Contains connective tissue, blood
vessels, hair follicles, sebaceous
glands, sweat glands, and white
blood cells (WBCs) such as macrophages, dendritic cells, and
mast cells.
Dermis
protein in epidermis that it makes the skin impermeable to most infectious agents.
keratin
helps maintain an acidic skin pH of approximately
5.6
Block bacterial adherence and
contain surfactants that bind
to and help remove microorganisms.
Mucous Secretions
Cilia in the nasopharyngeal
passages move approximately
90% of deposited material out
of the respiratory tract.
Ciliary Action
Mechanisms to expel pathogens.
Coughing and Sneezing
Flushing action and slight
acidity help remove pathogens.
Urine
production maintains a vaginal pH of about (), preventing
pathogen invasion.
Lactic acid; 5
pH of digestive tract
pH 1
Found in tears and saliva, this enzyme attacks the cell walls of microorganisms, particularly gram-positive bacteria.
lysozyme
Resident microorganisms that inhabit specific body sites and help prevent pathogen establishment by competing for
resources and producing antimicrobial substances.
normal flora
proteins in the gut that disrupt the membranes of certain bacteria.
colicins
consists of cells and soluble
factors that perform specific
and crucial functions in
combating infections.
INTERNAL DEFENSE
serve as sensors for
extracellular infections. they activate phagocytic cells, enhancing their ability to engulf and destroy invaders.
PATHOGEN RECOGNITION
RECEPTORS (PRRs)
distinguish self from non-self
by recognizing PAMPs, which are
specific to microorganisms
PATHOGEN-ASSOCIATED
MOLECULAR PATTERNS
TLRs that are found on cell surfaces
TLR1
TLR2
TLR4
TLR5
TLR6
TLRs that are found in the
endosomal compartment of a cell
TLR3
TLR7
TLR8
TLR9
Binding of TLRs to pathogens results in
▪ production of cytokines and chemokines
▪ recruitment of neutrophils
▪ enhanced macrophage and dendritic cell activity
acute phase reactants are found in what sample
serum
increase rapidly because of infection, injury, or trauma to the tissues.
ACUTE PHASE REACTANTS
acute pahse reactants are produced primarily in
hepatocytes
Bind to microorganisms and promote adherence (first step in phagocytosis)
Limit destruction caused by proteolytic enzymes from WBCs during phagocytosis
ACUTE PHASE REACTANTS
main reactive protein of c-reactive protein
opsonization
The body’s overall reaction to injury or invasion by an infectious agent
INFLAMMATION
The five cardinal signs of inflammation
Redness (erythema)
Swelling (edema)
Heat
Pain
Loss of function
Combats early stages of infection, repairs tissue damage
Acute inflammation
Prolonged inflammation due to failure to remove microorganisms or injured tissue, leading to continued tissue damage and loss of function
Chronic inflammation
Most active phagocytes
neutrophils
monocytes
macrophages
dendritic cells
other name of neutrophils
Polymorphonuclear Neutrophilic Leukocytes, Segmenters
Most abundant WBC in adults
neutrophils
nucleus in neutrophils
2 to 5 lobes
main function of neutrophils
phagocytosis
Movement through blood vessel
walls to tissues.
Diapedesis
Migration towards specific areas
guided by chemotactic factors.
Chemotaxis
Increase in allergic reactions or parasitic infections.
EOSINOPHILS
Represent less than 1% of all circulating WBCs.
Contain coarse, deep-bluish-purple granules that often obscure the nucleus.
BASOPHILS
Precursor for macrophages
MONOCYTES
Nucleus - Irregularly folded or horseshoe-shaped.
Cytoplasm - Ground-glass appearance with fine dust-like
granules.
MONOCYTES
Arise from monocytes.
Differentiation and cell division occur in tissues.
MACROPHAGES
fxns of macrophages
Innate Immunity
Activation
Adaptive Immunity
play a role in allergic reactions, but they can also function as antigen-presenting cells (APCs).
They can both enhance and suppress the adaptive immune response.
MAST CELLS
Named for long membranous extensions resembling nerve cell dendrites.
DENDRITIC CELLS
First line of defense against
virally infected cells, intracellular
pathogens, and tumor cells
Eliminate target cells without
prior exposure
Lack specificity, essential for early
defense
NATURAL KILLER CELLS
Binding Receptors on NK Cells
Inhibitory Receptors
Activating Receptors
Deliver inhibitory signals
Inhibitory Receptors
Trigger cytotoxic mechanisms
Activating Receptors
Healthy cells inhibitory signals from
class I MHC proteins
Lack MHC proteins (“missing self”), activating signals from stress proteins
Diseased/cancerous cells
form channels (pores) in target cell membrane
Perforins
enter through channels, mediate cell lysis
Granzymes enter
nkc elimination of target cells in how many minutes
30-60 minutes
NK cells recognize and lyse antibodycoated cells
Antibody-Dependent Cell Cytotoxicity
Specificity for individual pathogens
Ability to remember prior exposures
Increased response upon repeated exposure
ADAPTIVE IMMUNITY
Mature in the bone marrow
Differentiate into plasma cells
Produce antibodies
B cells/lymphocytes
Based on clonal selection, expansion, and differentiation of antigen-specific T and B cells
Greater speed and intensity in response to re-encounter with the same pathogen
Protects host from reinfection
Immunologic Memory
Differentiation starts very early in fetal development
Lymphocyte Maturation
Early precursors enter the thymus at the … and migrate to the outer cortex
corticomedullary junction
Drive migration
Recruit specific cells to particular sites
Chemokines
Precursors committed to becoming T cells
Undergo gene rearrangement for antigen receptor
Display distinct surface markers during development
Thymocytes
Lack CD4 and CD8 markers
Double-Negative (DN) Thymocytes
Random gene rearrangement builds diversity
TCR consists of alpha (α) and beta (β) chains
T-Cell Receptor (TCR) Gene
Rearrangement
Express both CD4 and CD8 antigens
Double-Positive (DP) Thymocytes
Allows only DP cells with functional TCR receptors to survive
T cells must recognize foreign antigen with MHC molecules
Positive Selection
Eliminates clones capable
of autoimmune response
Negative Selection
recognize antigen with class
II MHC
CD4+ T
cells interact with antigen and
class I MHC
CD8+ T
protect cells against intracellular pathogens by activating cytotoxic lymphocytes and macrophages
T helper 1 cells
help B cells produce antibodies against extracellular pathogens and to generally regulate
B-cell activity
T helper 2 cells
Have proinflammatory effect
Stimulate growth of hematopoietic cells (mast cells); may promote autoimmune inflammation
T helper 9 cells
Increase inflammation and joint destruction
Associated with autoimmune disease
T helper 17 cells
Th17 cells produce
IL-17
IL-22
Leave secondary lymphoid tissues, target infection sites
Bind and kill infected cells via apoptosis, antigen-specific
CYTOTOXIC T CELLS
Differentiate into cytotoxic lymphocytes, proliferate,
migrate to affected tissues
CYTOTOXIC T CELLS
result of cytotoxic t cells
Apoptosis
The earliest stage requiring direct contact with stromal cells and involving several transcription
factors.
progenitor B cells
Heavy and light chain genes rearrange to create specific antibody molecules
progenitor B cells
interacts with stromal cell factors to trigger gene rearrangement.
C-Kit
B cells remain in the spleen
Marginal zone B cells
B cells circulate in secondary
lymphoid organs
follicular B cells
Their primary role is antibody
production.
PLASMA CELLS
used to identify and differentiate between different types of cells
CLUSTERS OF DIFFERENTIATION
Identified by the presence of CD19 and surface antibody.
B cells
Identified by the presence of CD3, CD2, and either CD4 or CD8.
T cells
Primarily identified by CD4.
Helper T cells
Primarily identified by CD8.
Cytotoxic T cells
Identified by CD16 and CD56.
Natural Killer (NK) cells
