Introduction Flashcards
what does a cytokine do?
mediates inflammatory and immune reactions
what is the physiologic function of the immune system?
prevent and eradicate infections and eradicate cancers
does an antigen induce a specific immune response?
not always
what are the principal components of innate immunity?
anatomical and chemical barriers
effector cells
inflammation
what are the most important professional antigen presenting cells?
dendritic cells
what do neutrophils do?
kill extracellular pathogens
phagocytose
what secretes cytokines?
macrophages
what are the two professional antigen presenting cell types?
dendritic cells and macrophages
how do macrophages deal with pathogens/foreign antigens?
capture them, lyse them, and present them to T cells
what cells are important in linking innate and adaptive immune responses?
dendritic cells
true/false: macrophages and neutrophils can phagocytose intracellular pathogens if those pathogens are present in extracellular spaces
true
what is phagocytosis and killing of microbes?
when a phagocyte binds and phagocytoses a pathogen or surface molecule, then entraps it in the phagosome, which fuses with the lysosome to form a phagolysosome. Enzymes of it kill the microbe
what cells are phagocytes?
neutrophils, macrophages, and dendritic cells
what reactions do basophils contribute to?
inflammation and allergic reactions
what do eosinophils do?
secrete the contents of their granules to damage parasitic membranes
what cells have the most heavily granulated cytoplasm?
mast cells
what cells directly kill other cells?
natural killer (NK) cells
how do natural killer cells kill other cells?
secrete perforin and granzymes (proteins)
perforin makes holes in the cell membrane to allow granzymes through, which induce apoptosis
what is hypersensitivity?
when inflammation goes too far and causes a lot of damage to the host’s tissues, even death
what are the first four hallmark signs of inflammation?
rubor (redness- increased blood flow), calor (heat- increased blood flow), tumor (swelling- edema and proteins), dolor (pain- stimulation nerve endings)
do arteries and arterioles or venules contribute to inflammation (extravasation)?
venules
what are the effector cells of adaptive immunity?
B and T lymphocytes (B and T cells)
what cells can be recruited into an inflamed site?
neutrophils (primarily), lymphocytes, and monocytes and other cells
what do T cells recognize?
only protein antigens
what do B cells recognize?
protein, carbohydrate, and lipid antigens
the whole Baboodle
what cells express antigen receptors?
B and T cells
what are the two main characteristics of adaptive immunity?
specificity/specific immunity and memory/acquired immunity
what is an immunogen?
an antigen that always induces an immune response
what are hapten and carrier?
a small chemical on a macromolecule to induce an immune response
what are epitopes or antigenic determinants?
regions against which immune responses are directed
what are the two types of epitopes?
linear and discontinuous/conformational
what is the basis of diversity with lymphocytes?
an unvaccinated animal will have clones of lymphocytes with different specificities, for antigens they have never been exposed to
what is lymphocyte repertoire?
the total number of antigenic specificities of the lymphocytes an individual has
true/false: immunocompetent dogs that have never been exposed to antigens of canine parvovirus have a small fraction of B cells with B cell receptors specific to canine parvovirus
true
true/false: ten dogs vaccinated a month back for the first time against canine parvovirus, but not the 40 unvaccinated dogs, have a small fraction of B cells with B cell receptors specific to canine parvovirus
false. they all have some
true/false: ten dogs vaccinated a month back for the first time against canine parvovirus, but not the 40 unvaccinated dogs, have memory B cells with B cell receptors specific to canine parvovirus
true
do dogs have a small fraction of B cells with B cell receptors specific to feline immunodeficiency virus?
yes
do naive or memory cells respond more rapidly and vigorously to antigen challenge?
memory cells
what is tolerance?
self recognition so that you do not kill your own healthy cells
what are the two types of adaptive immunity?
humoral immunity
cell-mediated or cellular immunity
what cells produce antibodies or immunoglobulins that mediate humoral immunity?
B cells
do naive B cells secrete antibodies into the extracellular space?
no
what are plasma cells?
terminally differentiated, non-dividing effector B cells
what does the activated B cell (no longer naive) differentiate into?
effector B cells (plasma cells) and long-lived memory B cells
why do we need antibodies?
they play a major role in defense against microbes and their toxins
do T cells secrete their T cell receptors?
no, they only express 10^5 identical T cell receptors
when do T cell receptors on T cells recognize antigens?
when antigens are presented to them by professional antigen presenting cells
do the major histocompatibility complex molecule of antigen presenting cells present carbohydrates or lipids?
no- only proteins
what are the two types of effector T cells?
helper (helper through cytokines) and cytotoxic (killer function- kill cells infected)
how do T cells kill cells?
perforin and granzymes
why are T helper cells considered a part of cellular immunity?
they provide help to various immune cell types including macrophages, eosinophils and T cytotoxic cells
what are the effector cells of innate immunity?
macrophages
neutrophils
dendritic cells
natural killer cells
mast cells
eosinophils
basophils
true/false: a pathogen always expresses more than one antigen, each bearing many epitopes
true
from what do lymphocyte precursors arise from?
pluripotent stem cells in bone marrow
where do lymphocyte precursors undergo maturation and development?
primary lymphatic organs
where do T cells go to become immunocompetent (still naive)?
thymus
where do B cells go to become immunocompetent (still naive)?
bone marrow
cloacal bursa
Peyer’s patches
what cells replace the connective tissue in most lymphoid organs?
epithelial cells (epithelioreticular cells)
what do epithelial cells do that replace the connective tissue in the thymus?
mechanical support
secrete cytokines
sheath blood vessels
where are Hassall’s corpuscles found? what cells are they made up of?
thymus
epithelioreticular cells
does the thymus have efferent and/or afferent lymphatics?
efferent only
what is a thymoma?
a malignancy of thymic epithelial cells after sexual maturity
what makes up the outer layer of the cloacal bursa?
epithelium
what promotes B cell differentiation in the cloacal bursa?
epithelial (reticular) cells
where are Peyer’s patches found (primary lymph organ)?
distal ileum of small intestine
ruminants, carnivores, pigs
where do B cell precursors start in the bone marrow?
near endosteum of bone, move toward venous sinuses
what is the purpose of secondary lymphoid organs?
immunosurveillance and response to foreign antigens
where is diffuse lymphoid tissue found prominently?
lamina propria of tubular organs
what is found in secondary nodules of lymphoid tissue?
large proliferating lymphocytes on inside (germinal center), small naive on outside (mantle zone)
are interfollicular areas B cell or T cell rich?
T cell rich
what are the tonsils?
secondary lymphoid tissue in oro- and nasopharynx
does the tonsil have afferent lymphatics?
no
where are Peyer’s patches most commonly found (secondary lymph organs)?
jejunum and proximal ileum
what do microfold cells do?
pinocytose particulates in lumen and present them to lymphocytes and dendritic cells in basolateral pockets
what lymphatic organs have afferent lymphatics?
lymph nodes
where are B cells and T cells in the lymph nodes?
B cell superficial cortex
T cells deeper cortex in zones
medulla: cords and sinuses
what are sinuses for in lymph nodes?
allows lymph to pass into sinus
allows lymph to pass into parenchyma
macrophages hunt for antigen
what type of vessels are found in the paracortex of lymph nodes after the capillaries?
high endothelial vessels make up venules
how do most lymphocytes enter the lymph node?
via high endothelial venules lines by tall, simple cuboidal endothelium
how do B cells leave the lymph node in an immune response?
medullary cords to medullary sinuses
what makes up the capsule of the spleen?
mesothelium, connective tissue, +/- smooth muscle
what is in the white pulp of the spleen?
organized lymphoid tissue: periarteriolar lymphatic sheath and lymphoid nodules
do B cells or T cells predominate near the periarteriolar lymphatic sheath?
T cells
how do lymphocytes get into the spleen?
migrate from capillaries in zone between white pulp and red pulp
what species have nonsinusoidal spleens (no splenic sinuses: open circulation)?
cats, horses, oxes, pigs
true/false: sinuses function as a mechanical filter and pinch off red blood cell inclusions
true
what removes abnormal red blood cells in nonsinusoidal spleens?
macrophages
what do antigens do?
bind to microbes outside cells, neutralize them, facilitate their removal
what are the phagocyte types?
neutrophils, macrophages, and dendritic cells
what cell type predominantly surrounds central arteries in spleens?
periarteriolar lymphatic sheath of T lymphocytes
where are sheathed capillaries in spleens and what surrounds them?
in red pulp, surrounded by periarteriolar macrophage sheath
how do you distinguish between a tonsil slide and a lymph node slide?
tonsil will have epithelium over at least half of it (stratified squamous epithelium)
what cells are in germinal centers in lymph nodes?
large activated B cells
how do most lymphocytes enter the lymph node?
high endothelial venules
where are T cells found in lymph nodes?
surrounding B cell nodes (germinal center with corona)
is the thymus a primary or secondary lymphoid organ?
primary
how do lymphocytes enter and leave the thymus?
enter via cortical capillaries
leave via post-capillary venules or efferent lymphatics
what tissue type is a prominent component of the splenic parenchyma and trabecula?
smooth muscle
where are high endothelial venules found?
lymph nodes
