immunology lect 1

immunology is the

study of the immune system and its responses to various insults

immunology defends against

pathogens

Herd health contains

serodiagnostics, vaccination

exaggerated or deficient responses include

immune-mediated disease, immunodeficiencies

innate immune system is a part of the immune system that is

in place at birth, at location of an offense, somewhat non-specific, responds immediately to an offense

innate immune system also contains

physical/physiological barriers, antimicrobial molecules, sentinel/phagocytic cells

epithelium has

tight junctions, cell turnover

factors of mucus/tears/sebum

pH, lysosome, bile, pancreatic enzyme

physical/physiological barriers are

epithelium, mucus/tears/sebum, flushing/peristalsis, commensal flora

antimicrobial molecules are produced

by epithelial cells and leukocytes,

types of leukocytes

defensins, cathelicidins

antimicrobial molecules direct

toxicity to bacteria, fungi, protozoa, enveloped viruses, tumor cells

antimicrobial molecules activate

leukocytes

antimicrobial molecules bind/neutralize

lipopoysaccharide, microbial toxins

antimicrobial molecules stimulate

wound healing, vascularization

2 types of opsonins

complement proteins, mucosal antibodies

type of complement proteins

C3b

3 types of mucosal antibodies

IgM, IgA, IgG

opsonins intersect

adaptive and innate immunity

extracellular molecules bind to microbes,

more susceptible to phagocytosis

3 types of sentinel cells

mast cells, macrophages, dendritic cells

mast cells

initiate inflammation

macrophages take care of

inflammation and phagocytosis

dendritic cells

process antigen to start adaptive response

sentinel cells come from

hematopoiesis

sentinel cells are mainly in

the bone marrow

hematopoiesis contains

erythroid, myeloid, lymphoid, platelets

myeloid contain

granulocytes, mast cells, monocytes/macrophages, myeloid dendritic cells, platelets

lymphoid cells include

T and B cells, natural killer cells

bone marrow activity is seen

throughout most skeletal ones in young animals

bone marrow activity in adults happens in

flat bones, promixal ends of humerus and femur

types of flat bones

vertebrae, sternum, ribs, pelvis

common myeloid progenitors comprise of

innate immune cells and other blood cells

CNS macrophage

microglia cells

liver macrophage

Kupffer cells

lung macrophage

alveolar macrophages

bone macrophage

osteoclasts

dendritic cells, mucous membranes

sentinel cells in skin, lungs, and gut

after dendritic cell captures a threat

it sends it to lymph node

lymphocytes develop in

the bone marrow

lymphocytes mature in the

generative lymphoid organs

B lymphocytes are in

bone marrrow in mammals, bursa of fabricius in birds

T lymphocytes are in

thymus

mature, but naive B and T cells circulate

through blood to 2nd lymphoid organs

monocytes are bigger than

granulocytes

no granule staining cell

neutrophil

pink granule staining cell

eosiniophil

blue/purple granule staining cell

basophil/mast cell

orange-pink granules cells

heterophils

neutrophils have

2-5 segments in their nucleus

neutrophil cytoplasm

clear, neutral granules

neutrophils mainly

circulate in blood

neutrophils primary function

kill infecting microbes via phagocytosis, degranulation, neutrophil extracellular traps

neutrophils are the

first responders to a pathogen in tissue

heterophils

act like neutrophils

bird and rabbit heterophils lack

significant myeloperoxidase activity

neutrophil extracellular traps have their

nuclear contents extruded

NETosis

captures microbes, kills them, destroys virulence factors

Is NETosis a passive process (accidental cell death) or an active process?

Active process

NETosis are abundant at

sites of acute inflammation

NET is physically made of

DNA coated w/histones and granule components

3 things that a NET does to a microbe

capture, kill, destoy its virulence factors

What percentage of blood leukocytes are eosinophils?

0.1-3%

How long do eosinophils spend in the blood before entering tissue?

about 30 min in dogs

What are the three main functions of eosinophils?

Parasitic killing, participating in hypersensitivity reactions, and promoting inflammation

In which species are basophils unusually abundant?

Rabbits (10–15%), turtles/tortoises (30–60%), and birds

Which other cell types do basophil functions resemble?

Eosinophils and mast cells

What are the three listed functions of basophils?

Hypersensitivity reactions, participation in coagulation (blood clotting), and rejection of parasites

Which blood leukocyte is the largest?

monocyte

What percentage of blood leukocytes are monocytes?

2-10%

How long is a monocyte's blood transit time?

12-24 hrs

What are monocytes the circulating precursor of, and what do they do to become that?

Macrophages and dendritic cells; they enter tissue to differentiate

Describe the monocyte's nucleus shape

Highly pleomorphic — oval, reniform, horseshoe-shaped, often with bulbous ends, bi- or tri-lobed

Describe monocyte chromatin

Smooth, lacey chromatin

Describe monocyte cytoplasm

Blue-gray cytoplasm, often with a few vacuoles (clear areas)

What cell type do dendritic cells develop from?

monocytes

Where do dendritic cells reside?

In connective and lymphoid tissues

What gives dendritic cells their name/shape?

Dendrite-like processes

Describe the dendritic cell's nucleus and cytoplasm

Round nucleus, clear cytoplasm

What are the three functions of dendritic cells?

Acting as a sentinel, endocytosis/phagocytosis, and antigen presentation

Where do mast cells reside?

In connective tissues near blood vessels and nerves

What shape are mast cells?

round

Why is the mast cell nucleus often not visible?

Because the cell is packed with granules

Describe mast cell granules.

Fine, magenta to basophilic granules

What are the four functions of mast cells?

Vasodilation, increasing vascular permeability, recruiting other leukocytes, and driving allergic responses

What lineage do NK cells belong to?

Lymphoid lineage

How do NK cells differ from T and B cells in 2 ways?

unlike T and B cells, they don't need prior sensitization and don't express T or B cell receptors

Where do NK cells mature?

In secondary (2°) lymphoid organs

What percentage of circulating lymphocytes are NK cells?

5-15%

Describe NK cell morphology

Similar to other lymphocytes, can have fine, azurophilic cytoplasmic granules.

What is the function of NK cells?

First line of defense against viruses and some tumors

what do NK cells secrete?

they secrete cytotoxic granules that drive apoptosis

What does a band neutrophil's nucleus usually look like?

A "C"-shaped or horseshoe-shaped nucleus

What is a CBC (complete blood count)?

A group of tests designed to systemically evaluate the hematopoietic system, arranged in a report form

What three broad categories of blood components does a CBC evaluate?

Red blood cells, platelets, and leukocytes (including leukocyte subsets)