Leukocytes Flashcards
1
Q
What is the Proliferative pool of Neutrophils?
A
- Includes the:
- Myeloblast
- Proganulocyte
- Myelocyte
2
Q
What is the maturation pool of neutrophils?
A
- Includes the:
- Metamyelocyte
- Band neutrophils (immature neutrophils)
- Can be released during nonregenerative leukopenia
3
Q
What are the kinetics of neutrophils during health?
A
- Transit time in marrow - 7-10days
- Storage pool - Relatively large supply of mature neutrophils in most species
- Ruminants have small reserves
- Blood transit time: ~6-10hr
- Tissue Lifespan: 24-48hr
- Destroyed by macrophages in tissue (~90%)
- Lost in secretions from mucous membranes (~10%)
4
Q
What is the function of Neutrophils?
A
- Inflammatory response chemotaxis & phagocytosis - Innate immune response
- Neutrophils in blood are in transit from site of production to site of function
5
Q
What is a “left shift”?
A
-
Increased numbers of immature neutrophils in peripheral blood
- Bands, +/- metamyelocytes & myelocytes
6
Q
What is a Regenerative Left Shift?
A
- Expected response
- Bone marrow is able to keep up
- Leukocytosis due to neutrophilia
- [segs] > [non-segs]
7
Q
What is a Degenerative left shift?
A
- Bone marrow is NOT keeping up with demand
- Any time [non-segs] > [segs]
- Leukopenia due to neutropenia with a left shift where >10% of neutrophils are immatuer
8
Q
What does a Band Neutrophil look like?
A
- Generally parallel sides
- Lacks definitive indentation
- “Hallmark of acute inflammation”
9
Q
What do segmented neutrophils look like?
A
- Definitive indentation in nuclear outline
10
Q
What are Toxic Changes in Neutrophils?
A
- Likely the most common morphologic WBC abnormally identified on the blood films
- Occurs d/t increased stimulus for neutrophil production
- Storage pool of neutrophils in the bone marrow has been depleted
- Accelerated neutrophil production results in aberrant granulopoiesis
- Includes:
- Diffuse cytoplasmic basophilia
- Foamy cytoplasm
- Focal basophilia “Dohle body”
- Hyalinized nucleus
11
Q
What are the different mechanisms for Neutrophilia?
A
- Acute Inflammatory Neutrophilia
- Chronic Inflammatory Neutrophilia
- Steroid/stress Associated Neutrophilia
- Physiologic/Excitement Neutrophilia
12
Q
What is Acute Inflammatory Neutrophilia?
A
- Expected with significant inflammation of internal or subcutaneous tissue
- Mediators easily access systemic blood
- Not expected with lower urinary tract and superficial cutaneous lesions or oral cavity
- Mediators lost to urine, skin, oral cavity
- Often not seen with inflammation of the brain or spinal cord
- Mediators do not leave the protected environment
13
Q
What is Chronic Inflammatory Neutrophilia?
A
- Mediated by: Cytokines from inflammatory site ongoing for at least 1 week
- Mature neutrophilia - little or no left shift
- increased neutrophil release from storage pool
- Increased migration to tissues
- Granulocytic Hyperplasia
-
Does NOT always follow an acute inflammatory neutrophilia, even if the stimulus persists & there is some development of granulocytic hyperplasia seen when looking at the marrow
- If stimulus is severe or increases in intensity a left shift may persist or increase
- “Chronic” refers to the development of granulocytic hyperplasia and the bone marrow ‘catching up’
14
Q
What is Glucocorticoid-associated (“Stress”) Neutrophilia
A
- Common
- Mediated by cortisol, prednisone, prednisolone
- Neutrophilia w/ NO left shift
- may see hyper-segmented neutrophils (5+ lobes)
- Shift from Marginating to Circulating pool
- Increased release from storage pools
- Decreased migration to tissues
15
Q
What is Excitement/Physiologic Neutrophilia
A
- Especially in Cats where the Marginating Pool is ~3x Circulating Pool
- Mediated by: Catecholamines (epi/norepi)
- Causes a Mature neutrophilia
- Shift from marginating to circulating pool
16
Q
What are the mechanisms of Neutropenia?
A
- Severe, overwhelming acute inflammatory neutropenia
- Endotoxin neutropenia
- Granulocytic hypoplasia
- Ineffective Production
- Peripheral destruction - rare
*
17
Q
What is Severe, overwhelming, acute inflammatory neutropenia?
A
- Mediated by: Cytokines from inflammatory site
- Increased release of neutrophils from storage & maturation pools
- Neutropenia with left shift
- Increased migration to tissue
18
Q
When does neutropenia occur?
A
Neutropenia occurs because migration of neutrophils to inflamed tissue exceeds the release of neutrophils from the marrow
19
Q
How do endotoxins cause Neutropenia?
A
- Endotoxins and Cytokines stimulate sequestration of neutrophils in the marginating pool
- Will be seen as Acute Overwhelming Inflammatory Neutropenia
20
Q
What is Granulocytic Hypoplasia Neutropenia?
A
- Occurs when marrow cells or cells or the microenvironment are damaged
- Marrow disease causing decreased neutrophil production (decreased granulopoiesis)
- Infections, neoplastic, toxic, necrosis, myelofibrosis, drugs
-
Persistent neutropenia
- Usually NO left shift - may be present in infections or if the marrow is starting to produce cells
- Maturation is complete and orderly but decreased
21
Q
What is Ineffective Production Neutopenia?
A
- Occurs when neutrophils precursors are defective/damaged & die BEFORE release
- Diseases causing defective/ineffective granulopoiesis
- immune-mediated, drugs, G-CSF deficiency
- Lack of orderly and complete maturation of neutrophil sequence
- Maturation arrest commonly seen when
22
Q
What are some of the species differences when it comes to neutrophilia and neutropenia?
A
- Dogs:
- High marrow reserve
- Rapid regenerative capacity
- Neutrophilia up to 120,000 u/L
- Neutropenia in acute inflammation is a very sever lesion
- Cats:
- Intermediate Marrow Reserve
- Intermediate regenerative capacity
- Neutrophilia up to 60,000 u/L
- Neutropenia in acute inflammation is a very severe lesion
- Horses:
- Similar to cats
- Neutrophilia up to 30,000 u/L
- Neutropenia in acute inflammation is a probable severe lesion
- Cattle:
- Low Marrow reserves
- Slow Regenerative capacity
- Neutrophilia up to 25,000 u/L
- Neutropenia is a common finding regardless of severity as marrow reserves are low
26
Q
What is Chronic inflammation Lymphocytosis?
A
- Part of hyperplastic lymphoid response
- Chronic antigenic or cytokine stimulation
- increases production of lymphocytes
- May see reactive lymphocytes in blood
- Chronic antigenic or cytokine stimulation
- Concurrent Leukogram abnormalities:
- Neutrophilia (usually mature)
- Monocytosis
- +/- eosinophilia and/or basophilia
- Causes:
- Bacterial infections (E. coli)
- Fungal infections, primarily systemic
- Viral infections (FeLV)
- Protozoal infections, especially babesial and theilerial
27
Q
What are reactive lymphocytes?
A
- Immune stimulated lymphocytes
- Occur in upregulated synthesis
- inflammatory mediators
- immunoglobulins (antibodies)
- Active, systemic antigenic stimulation secondary to both infectious & noninfectious disorders
- defects include:
- Hyperchromatic nucleus
- Scant basophilic cytoplasm
- Hyperchromatic cleaved nucleus
- Prominent Goli zone
- Cytoplasmic basophilia
- Irregularly shaped nucleus
28
Q
What is Physiologic Lymphocytosis?
A
- Shift from marginating to circulating pool
- Usually lasts minutes to hours
- Morphologic changes in lymphocytes are NOT expected
- Causes: (Catecholamines)
- Fight or Flight response
- Catecholamine injections
29
Q
What is Lymphocytosis due to Lymphoid neoplasia?
A
- Neoplastic Transformation can occur in any tissue
- Increased production of neoplastic lymphocytes in bone marrow (leukemia)
- Increased production of neoplastic lymphocytes in the tissues or lymph nodes (lymphoma)
- Usually atypical, often medium or large lymphocytes in circulation
30
Q
What causes Lymphopenia?
A
- Acute Inflammation
- Corticosteroids
- Lymphoid aplasia or hypoplasia
- Depletion
31
Q
What is Acute Inflammatory Lymphopenia?
A
- Most acute inflammatory leukograms (neutrophilia & left shift) also have lymphopenia
- Increased migration of lymphocytes to inflamed tissue
- Decreased migration of lymphocytes from LN to blood
- “Homing” of lymphocytes to LN
32
Q
What is Steroid lymphopenia?
A
- Entire steroid leukogram:
- Mature neutrophilia, lymphopenia, +/- monocytosis and/or eosinopenia
- Decreased Lymphopoiesis
- Cytotoxic effects in those produced
- Decreased efflux from LN
- intermediate shift from Circulating pool to bone marrow and LN
35
Q
What is Monocytosis?
A
- Similar response as neutrophils - share a stem cell
- Not pathognomonic for anything in particular
- Present in Acute & chronic inflammation
- cytokine stimulation
- Steroid response
- Dogs>cats>horses & cattle
36
Q
Is monocytopenia concerning?
A
Usually not significant if present
37
Q
What are eosinophils?
A
- Contain proteins that bind & damage parasite membranes
- Important in allergic inflammation & immune-complex reactions
- Some phagocytic ability
- ineffective and not protective against bacterial infections
39
Q
What causes Eosinophilia?
A
- Hypersensitivity
- Parasitic diseases
- Mast cell degranulation (neoplasia or inflammatory)
- Addison’s disease (hypoadrenocorticism)
- Hypereosinophilic syndrome
- Paraneoplastic eosinophilia (chemoattractant agents in the neoplastic tissue)
- Others
40
Q
What causes Eosinopenia?
A
- Difficult to recognize
- By itself is of little diagnostic significance
- Corticosteroids:
- Stress leukogram
- Hyperadrenocorticism (Cushings)
41
Q
What are Basophils?
A
- Blood concentrations are low
- very low in dogs/cats
- higher in ruminants/equids
- Contain histamine & heparin
- Role in Type-1 Hypersensitivity
- Role in delayed-type hypersensitivity
- Proinflammatory cells
42
Q
What causes Basophilia?
A
- Rare
- Hypersensitivity
- Parasitic disease
- Neoplasia
43
Q
What causes basopenia?
A
cannot be documented with routine leukocyte differential counts
45
Q
Where are mast cells located?
A
- Occasionally seen in peripheral blood
- Inflammation
- Mast cell neoplasia
- Often in tissue (cytologic preparations
- Inflammation
- Mast cell neoplasia
49
Q
What are some of the classic Leukogram patterns?
A
- Normal
- Physiologic leukocytosis (excitement)
- Stress/corticosteroid leukogram
- Severe, overwhelming, acute inflammatory leukogram
- Chronic inflammatory leukogram
- Leukamoid (extreme neutrophilic leukocytosis)
- Neutrophils >50,000
- Eosinophilic inflammation
- Leukemia (discussed later)
