White Blood Cell Function

progenitor cell

what do pluripotential cells proliferate into?

precursor cells

what do progenitor cells proliferate into?

colony stimulating factors released by macrophages

what is the proliferation of white blood cells based on?

myeloblast through myelocyte

what stages do cells proliferate from?

5 to 7 days

how long do cells remain in the marrow?

several hours

how long do white blood cells remain in circulation after being released into the blood?

1-2 days

how long do white blood cells spend in the tissue after circulation?

peripheral blood

where are bands and segmented neutrophils found?

<5%

what percent of neutrophils will be bands in the peripheral blood?

50-70%

what percent of white blood cells are segmented neutrophils and bands?

• circulating neutrophils

• marginating neutrophils

what are the two groups of neutrophils in the peripheral blood?

neutrophils circulating in the peripheral blood → ready to go into the tissue

how are circulating neutrophils characterized?

• adjacent to the endothelial lining of the vessel

• can be mobilized into the blood by epinephrine or go into the tissue

how are marginating neutrophils characterized?

the ones remaining after two days

which neutrophils are destroyed?

macrophages in the spleen

what removes neutrophils?

• primary

• secondary

• tertiary

what are the three types of neutrophilic granules?

primary and secondary granules

which granules are stained with Wright’s stain?

azurophilic

what are primary granules also called?

nonspecific

are primary granules specific or nonspecific?

myeloperoxidase

what do primary granules contain?

an enzyme that aids in killing microorganisms

what is myeloperoxidase?

promyelocyte

what precursor cells forms abundant primary granules?

there is a large number of secondary granules, thus obscuring the primary granules

why are primary granules hard to see in neutrophils?

activate proteinases to kill bacteria

what is the purpose of primary granules?

no

are primary granules as effective in killing bacteria as secondary granules?

specific

are secondary granules specific or nonspecific?

myelocyte

which precursor cell do secondary granules first appear in?

the amount increases

how does the amount of secondary granules change with each cell stage?

lysozymes and other enzymes

what do secondary granules contain?

• hydrolyzes bacteria cell wall

• helps with inflammation

what is the purpose of lysozymes and other enzymes contained in the secondary granules?

there will be increased or recurrent infections and the cell is unable to kill the bacteria

what happens when primary or secondary granules are absent?

humoral response

what response are granules apart of in the innate immune system?

the ingestion and destruction of invading microorganisms

what is the primary function of the neutrophil?

cytoplasm

where does the primary function of neutrophils occur?

cell reproduction—not immunity

what is the nucleus of neutrophils involved in?

bone marrow and peripheral blood

where are granulocytes found?

bone marrow

where are the majority of granulocytes found?

go to tissue

where do cells in circulation go during an infection?

mature cells

what does the bone marrow release during an infection?

granulocytes

what do stem cells commit to during an infection?

maturation

what is increased during an infection?

bands, metamyelocytes, and myelocytes

what precursor cells are released if necessary during an infection?

blasts

what precursor cell is never released during an infection?

extra cell divisions

what also occurs during an infection to get more cells?

• chemotaxis

• opsonization

• phagocytosis

what are the steps to phagocytosis?

• degranulation/fusion

• killing

• inflammation

what are the steps to killing an organism?

neutrophils are attracted to site of infection

what occurs during chemotaxis?

chemotactic factors

what notifies the cell during chemotaxis?

• antigen-antibody

• C5a

• organism

what are some examples of chemotactic factors?

bind to chemotactic factor and go to area of infection

what is the function of neutrophils during chemotaxis?

vessel wall between endothelial cells

how do cells pass through during chemotaxis?

“recognizes” antibody or complement coated organism

what is the function of neutrophils during opsonization?

bacteria with a capsule

what can resist the recognition during opsonization?

surround it and moving it with pseudopods

how do neutrophils ingest the opsonized organism during phaocytosis?

phagosome

what do pseudopods form when they meet and fuse?

granules of neutrophil fuse with phagosome and discharge

what is the function of degranulation or fusion?

the granules becomes activated

what is result of primary and secondary granules during degranulation/fusion?

reduces oxygen to generate hydrogen peroxide—causing oxidative/respiratory burst

how do neutrophils kill?

myeloperoxidase from degranulation reacts with hydrogen peroxide created from oxidative burst to form hypochlorous acid

what is the mechanism of neutrophil killing?

lipid damage to microbial membrane

what does neutrophil killing cause?

lysozymes and other granules

what may kill the organism before the killing pathway is completely activated?

granules and metabolites leaking into surrounding tissues

what causes inflammation?

to fight infection

what does the granulocyte give it’s life to?

it is phagocytized by macrophages

what happens if the granulocyte survives fighting the infection?

% based on a 100-cell differential 

what is the relative white blood cell count?

relative % x WBC

what is the absolute white blood cell count?

mid-afternoon

when is the white blood cell count the highest?

increased number of neutrophils

what is neutrophilia?

leukocytosis

what does neutrophilia usually coincide with?

left shift

what is seen with leukocytosis and neutrophilia?

leukemoid reaction

what is neutrophilia also referred as?

• infection

• stress

• inflammation

• physical stimuli

• hematologic disorders

• pregnancy

• burns

what are some possible causes for neutrophilia?

pain, cold heat—related to demargination

what physical stimuli can cause neutrophilia?

leukemia, hemolysis, hemorrhage

what hematologic disorders can cause neutrophilia?

increased need for cells

how does pregnancy cause neutrophilia?

stress, heat, and inflammation

how do burns cause neutrophilia?

within one hour of stimulation

when does the bone marrow respond to neutrophilia?

production

what does the bone marrow increase in response to neutrophilia?

monocytes, T cells, endothelial cells

what cells release CSF during neutrophilia?

bacteria and phagocytosis

what activates the release of CSF by monocytes, T cells, and endothelial cells?

the sinusoids to release younger cells—causes left shift

what do the releasing factors stimulate?

during infection

when are qualitative neutrophil changes observed?

• toxic granulation

• dohle bodies

• vacuolization

what are the qualitative changes of neutrophils?

prominent cytoplasm granules

what is toxic granulation?

strands of endoplasmic reticulum RNA

what are dohle bodies?

phagocytosis

what are vacuoles a result of?

mature neutrophils less than 1500 cells/µL

what is neutropenia?

recurrent bacterial infections

what does neutropenia cause?

• failure of production

• failure of bone marrow to release

• destruction

• misdistribution

what causes congenital neutropenia to occur?

acquired neutropenia

which is more common congenital neutropenia or acquired neutropenia?

• viral infections

• depletion of neutrophil storage pool in marrow

• chemotherapy or other drugs

• blood malignancies

what causes acquired neutropenia?

1-5%

what is the normal range of eosinophils?

parasites

what are eosinophils more involved in?

by secretion of major basic protein and eosinophil cationic protein

how are eosinophils involved in parasites?

directly on target

how do eosinophils discharge toxic granules?

allergies, parasitic infections, chronic myeloid leukemia

when are eosinophils increased?

decreased relative number

what number of eosinophils are hard to detect?

absolute eosinopenia

what type of eosinopenia can be detectd?

<90 eosinophils/µL

how is absolute eosinopenia defined?

basophils

what cell has the smallest percentage of white blood cells?