Leukocytes Flashcards
What are the two bone marrow pools? How long do cells spend in each?
Proliferation pool - 3 days
Maturation pool - 2 days
- Total time spent in health: 5 days*
- Total time spent in disease: <5 days*
What are the two WBC blood pools
Circulating pool (veins and arteries)
Marginated pool (capillaries - stuck to endothelium)
How much time is spent in blood pools in health? In inflammation?
Health: 8hrs
Inflammation: <8hrs
3 lymphocyte migration paths
- Lymph node path (blood –> LN –> efferent lymphatics)
- Tissue path (blood –> tissues –> lymphatics
- Blood path (capillaries –> tissues –> LNs)
Different ways to count WBCs in lab (5)
1. Imependence cell counters
2. Electronic cell counters
3. WBC differential count (microscope)
4. Centrifugation (IDEXX)
5. Hemacytometer
How do impedence cell counters work? Downsides of them?
- Lyse RBCs and platelets
- Send electrons through. Nucleated cells impede electrons
- Counts cells with nuclei
* Problem: count all nucleated cells (including immature RBCs)*
* Technically a total nucleated cell count*
How do electronic cell counters work
- Optical/laser flow
- Stain nuclei/cytoplasm
- ID cells by light scatter and absoprtion
Downsides of electronic cell counters
- Dont ID abnormal cells correctly
- Dont detect organisms
- Technically a total nucleated cell count
Whats a WBC differential count. Downsides?
- Count 100 WBCs with microscope
- Determine percentage of each
- Multiply percentage by [WBC] to get individual concentrations
* Poor precision*
* Poor reproducibility*
Centrifugation (IDEXX)
- Centrifugal forces separate blood into 5 layers
- Layers recognized by fluorescent markers of DNA, RNA, lipoprotein
- Thickness used to get concentration
Leukocytosis
Elevated WBC count
Due to:
- Acute/chronic inflammation
- Glucocorticoids
- Physiologic (excitement)
- Neoplasia
Neutrophilia
Increased neutrophils
Due to:
- Increased release from marrow
- Shift from marginating pool to circulating pool
- Decreased migration to tissues
- Or all of the above*
Whats left shift
Increased banded neutrophils
Regenerative left shift
[Segs] > [Bands]
Adequate response to inflammation
Degenerative left shift
[Bands] > [Segs]
- Inadequate response: marrow is not keeping up with demand*
- Poor prognosis :(*
- Normal in cows!*
Your patient is a cow with elevated bands but normal segs, suggesting a degenerative left shift. Are you worried?
No, this is normal in cows due to smaller storage pools
How do quantify the severity of neutrophilia?
- Mild: <1,000/ul [bands]
- Moderate: 1,000 - 10,000/ul
- Severe: >10,000/ul
Whats a right shift? What causes it?
Hypersegmented neutrophils
Cause
- Glucocorticoids (decreased immigration of neutrophils to tissue, increased lifespan in blood –> larger)
Which species have highest [neutrophil] with inflammation
Dogs
Pathogenesis of acute inflammatory neutrophilia
- Acute inflammtory disorder (hours-days)
- Macrophages and lymphocytes release cytokines
- Cytokines stimulate release of neutrophils from storage pool
—> Neutrophilia
- Cytokines stimuate release of bands from maturation pool
—> Left shift
- Cytokines stimulate production of neutrophils (granulocytic hyperplasia – after several days)
—> Regenerative
Magnitude of glucocorticoid neutrophilia
< 3x URI
Magnitude of acute inflammatory neutrophilia
>10x URL
Extreme inflammation = leukemoid response (increased WBC)
60-80,000 neutrophils
Pathogenesis of chronic inflammatory neutrophilia
1) Chronic inflammation (*weeks to months*)
2) Macrophages and lymphocytes release cytokines
—-> increased neutrophil production (neutrophilia)
3) Granulocytic hyperplasia
—–> more segs produced
—> neutrophilia w/o left shift
Magnitude of chronic inflammatory neutrophilia
<3x URI (slight to moderate)
Pathogenesis Glucocorticoid Neutrophilia
- Glucocorticoids in blood (stress, iatrogenic)
- Reduced adhesion proteins in vessels
- Shift from marginated pool to circulation pool
——> NEUTROPHILIA
- Reduced neutrophil migration to tissue
——-> Immuno-compromised
- Increased lifespan blood neutrophils
——> Hypersegmented
——> sometimes RIGHT SHIFT
Why are patients on glucocorticoids immunocompromised
Glucocorticoids reduce migration of neutrophils to tissues –> fewer cells in tissue to fight pathogens
Pathogenesis Physiologic Neutrophilia
- Flight/flight stimulus
- Catecholamines
- Down regulation of adhesion proteins in vessels
- Neutrophils shift MP —> CP
——> Neutrophilia
- Increased blood flow rate through capillaries (vasodilation)
——> Shift from MP to CP
——> Neutrophilia (NO SHIFT!)
Magnitude physiologic neutrophilia
< 3 % URI
Except cats: >3% URI! Large marginated pool