white blood cells Flashcards
which cells exist in the mitotic pool? What about the maturation and storage pool? What is the important difference between these?
-mitotic pool in the bone marrow consists of myeloblasts, promyelocytes and myelocytes
>these cells divide
-maturation and storage pool consists of metamyelocytes, band and segmented neutrophils
>These cells are no longer able to divide
once segmented neutrophils are released into the blood, how long are they there for? Then what?
6-10 hours
-then move into tissues to help with inflammation/infection or apoptose
what are the two pools of neutrophils in circulation? How do these compare in size?
-circulating neutrophil pool, CNP
-marginating neutrophil pool, MNP
> pools of similar size except in cats, who have a larger MNP
what is the avian and reptilian equivalent to the neutrophil?
heterophil
what is the function of neutrophils, and how do they achieve this?
-protect predominantly against bacterial pathogens
>to a lesser degree against fungal, protozoal, parasitic or viral organisms
-Leave the blood stream by diapedesis, where they move through the endothelium of small capillaries, and phagocytose organisms
- chemotaxis controlled by complement system, coagulation of finbrinolytic systems, endotoxins, or chemokines
- recognize pathogens via opsonins
- ingest organism into phagosome
- phagosome fuses with granules
- reactions in phagolysosome kill organism
what cells are often incorrectly identified as WBCs by automated counters?
rubricytes (nucleated RBCs)
what do we call an increase in segmented neutrophils in circulation? What mechanisms can cause this?
-increase in mature circulating neutrophils
1. ephinephrine response - ‘physiologic’
2. stress leukogram
3. acute inflammation
4. chronic inflammation
5. tissue necrosis, neoplasia
what are the characteristics of physiologic neutrophilia? What is the mechanism?
Epinephrine response - ‘physiologic’
• Mild mature neutrophilia, no left shift
• Mild lymphocytosis
-more common in young animals
Mechanism:
Marginating neutrophils move into CNP. Lymphocytes remain in vasculature longer.
what are the characteristics of a stress leukogram? What is the mechanism?
• Mild to moderate mature neutrophilia
• Lymphopenia
• Possibly monocytosis and/or eosinopenia
-influence of cortisol
»Segmented neutrophils, monocytes increased
»Lymphocytes, eosinophils decreased
Mechanism:
Release of bone marrow storage pool of segmented neutrophils, longer circulation time, and decreased margination. Lymphocytes are retained in lymph nodes.
what are the characteristics of neutrophilia due to acute inflammation? what is the mechanism?
• Neutrophilia with moderate to marked left shift
Mechanism:
Depletion of segmented neutrophils and release of band (or younger) neutrophils from bone marrow
what are the characteristics of neutrophilia due to chronic inflammation? what is the mechanism?
• Marked neutrophilia with variable left shift
Mechanism:
Increased production and release of segmented neutrophils from bone marrow
what are the characteristics of neutrophilia due to tissue necrosis or neoplasia? what is the mechanism?
• Mild to marked mature neutrophilia, often with a left shift
Mechanism:
Cytokine-mediated increased production of neutrophils
what species may have only mild changes in neutrophil numbers despite marked inflammation? why?
mature ruminants, due to a smaller reserve of cells
what species produces a greater magnitude of neutrophilia in response to inflammation: dogs and cats vs horses and ruminants?
cats and dogs have neutrophilia of a far greater magnitude: 6-10x, vs 2-3x for horses and cows
in terms of inflammation, what does the degree of neutrophilia correlate with? What about the degree of left shift?
The degree of neutrophilia correlates with the intensity of the inflammatory stimulus, and the degree of left shift with acuteness
how does neutrophilia differ for contained vs draining lesions?
contained lesions hvae no ability for supprative material to leave
-draining have lower neut count, less stimulus for neut production as things can get out
what are leukemoid reactions?
‘similar to leukemia’, very high neutrophil counts
how does neutrophilia after surgical removal of a lesion behave?
-normal to find lots of neutrophils after surgery until down regulation occurs in the marrow; body has a delayed response to lesion removal
what are the two broad ways that neutropenia can occur?
- Tissue demand exceeds bone marrow storage
- Decreased neutrophil production
what do we see when tissue demand for neutrophils exceeds bone marrow storage? When does this occur?
neutropenia
• Occurs with acute suppurative inflammation
• Cattle often develop neutropenia in these circumstances
• Toxic changes and a left shift are common
what is a regenerative left shift?
segmented neutrophils outnumber band and metamyelocyte (or more immature) neutrophils
what is a degenerative left shift?
band and metamyelocyte neutrophils (or more immature) outnumber segmented neutrophils
what do we see when we have neutropenia due to decreased neutrophil production?
insults on dividing cells in the bone marrow: cytotoxic drugs, radiation therapy, estrogen toxicity, and parvovirus infections
- Due to the short life span of neutrophils their numbers are more affected than platelets and red blood cells
-Neutrophil counts below 0.5 x 106 strongly predispose to secondary infections, and thus are life-threatening.
how do most insults to the bone marrow manifest?
first with neutropenia, then with anemia or thrombocytopenia