White blood cell parameters Flashcards
What are Neutrophils
Neutrophils play an important role in the innate immune system
Neutrophils are the most numerous white blood cells found in the circulation
What is the origin for Neutrophils
Neutrophils are derived in the bone marrow from the myeloid cell line
How does neutrophil act in the immune defense
Neutrophils marginate and extravasate in response to a variety of chemotactic factors and function to phagocytose organisms
The phagosome is then fused with a lysosome within the cytoplasm
- the lysosome contains enzymes and microbicidal susbstances (e.g., reactive oxygen species)
The neutrophil acts to kill primarily bacteria, and occasionally fungal pathogens
What is neutrophilia
A neutrophilia is characterized by an absolute neutrophil counts of > 9.0 * 10^9/L
What are the characteristics of immature neutrophils
Immature neutrophils can be released into the blood stream when demand outstrips the number of available mature cells
Typically, these younger neutrophils:
- have less segmentation to their nuclei and are known as “bands”
- have a basophilic cytoplasm
- have small blue-grey cytoplasmic structures consisting of rough endoplasmic reticulum, called Döhle bodies
In case of severe infections or inflammatory processes, the bone marrow may release younger cells known as metamyelocytes and myelocytes
What are the characteristics of a stress leukogram
A stress leukogram can be seen in response to endogenous or exogenous corticosteroids
It is characterized by:
- mature neutrophilia
- lymphopenia
- eosinopenia
- (monocytosis is not commonly seen in cats)
What would be your differentials for neutrophilia
Physiological response
- catecholamine induced neutrophilia
- Fear, excitement, pain, anxiety
- transient neutrophilia
- erythrocytosis and lymphocytosis (in cats)
- neutrophilia induced by stress or by corticosteroids (endogenous or exogenous)
- physical or neurogenic stress, illness
- hypersegmented neutrophils
- stress leukogram
Infection
- Bacterial
- fungal
Inflammatory
- trauma
- burns
- immune-mediated
- other (e.g., pancreatitis)
Neoplasia
- paraneoplastic (lymphoma, carcinoma)
- myeloid leukemia
- necrosis/ulceration of tumor
Other
- uremia
- DKA
- immune-mediated hemolytic anemia
What is neutropenia
A neutropenia is defined as a neutrophil count of less than 2.5*10^9/L
What are the pathomechanisms leading to neutropenia
Neutropenia can be seen as a result of:
- infectious or inflammatory disease (consumption, decreased production, increased destruction)
- bone marrow disorders (decreased production)
- an idiopathic phenomenom
What would be your differentials for neutropenia
Increased use
- severe infection/sepsis
- endotoxic shock
Decreased production
- myelophtisis (neoplasia, fibrosis) (typically, these animals have more than one circulating cell line affected)
- myelodysplasia
- drug-induced (e.g., vincristine, doxorubicin, chlorambucil, methimazole, pyrimethamine, phenobarbitone, griseofulvin)
- viral (FeLV, FIV, Feline panleukopenia virus)
Idiopathic
- infrequently seen
What is the particularity of neutropenia induced by FeLV
The neutropenia seen with FeLV infection can be cyclical in nature, occuring every 8-18 days
What is the signification of lymphopenia in cats
A lymphopenia is often seen as a response to endogenous or exogenous corticosteroids (“stress leukogram”) and is a non-specific finding in many unwell cats
What is the signification of lymphocytosis
A lymphocytosis and the presence of “reactive” lymphocytes suggest antigenic stimulation
- increased number of granular lymphocytes may indicate viral infection
A higher than normal lymphocyte count can also be seen as a physiological response to excitemennt in cats
- this is usually accompanied by a mature neutrophilia and erythrocytosis
High lymphocyte numbers (>10000/µL) may also be observed with lymphoblastic leukemia and Stage V lymphoma
- although cytopenias may also be observed with these conditions
- often these conditions will be accompanied by the presence of circulating lymphoblasts
What are monocytes and what is their signification
Monocytes are the circulating precursors of tissue macrophages
In chronic inflammatory conditions, an increase in the monocyte count may be seen because of an overall increase in demand for macrophages at the tissue level
A mild monocytosis may also be observed as part of a stress leukogram
- not as commonly observed as in dogs
What are the two most common conditions associated with eosinophilia
Elevations in eosinophil count should prompt an investigation and/or treatment for parasitism
- the cat should be wormed and good ectoparasite control should be implemented
An eosinophilia is also commonly seen with allergies, particularly dermal
- although many of these turn out to be occult flea infestations
What would be your differentials for eosionophilia
Conditions commonly associated with circulating eosinophilia in the cat:
- dermatitis (e.g., flea allergy dermatitis, milary dermatitis, eosinophilic granuloma complex, food allergy dermatitis, atopy, mosquito bite hypersensitivity)
- respiratory disorders (e.g., allergic airway disease, lungworm infestation) - GIT disorders (e.g., endoparasites, eosinophilic enteritis) - Hypereosinophilic syndrome - Eosinophilic leukemia - Paraneoplastic (e.g., mast cell tumors, lymphoma, leukemia) - Heartworm disease
What is hypereosinophilic syndrome
Hypereosinophilic syndrome is a rare idiopathic disorder that is characterized by:
- a persistent and markedly increased peripheral circulating eosinophilia
- bone marrow hyperplasia of eosinophilic precursors
- widespraed organ infiltration by mature eosinophils (e.g., liver, spleen, bone marrow, GIT and associated lymph nodes)
What is the suspected cause of hypereosinophilic syndrome
It is thought that the condition arises due to clonal expansion of helper T-cells that secrete interleukin-5, which results in increased eosinopoeisis and eosinophil survival
what is the signalment of cats suffering hypereosinophilic syndrome
The condition tends to occur more frequently in middle-aged, female domestic shorthair cats
What are the clinical signs accompanying the hypereosinophilic syndrome
Clinical sign stend to depend on which organs are involved
Most commonly they reflect gastrointestinal disease (vomiting and diarrhea)
Non specific signs such as anorexia, weight loss, pyrexia and pruritus have also been reported
What is the prognosis and treatment for hypereosinophilic syndrome
The prognosis is generally poor because cats usually respond minimally to treatment
A combination of prednisolone and cyclosporine was successful in one cat
Other potential treatments include:
- tyrosine kinase inhibitors
- anti-IL-5 antibodies
- IL-5 receptor blockers
What is the difference between eosinophilic leukemia and hypereosinophilic syndrome
Eosinophilic leukemia is also characterized by peripheral eosinophilia, bone marrow hyperplasia of eosinophilic precursors, and multiple organ infiltration by eosinophils BUT the eosinophils tend to be immature
The clinical presentation of eosinophilic leukemia is similar to hypereosinophilic syndrome
What are the prognosis and treatment for eosinophilic leukemia
The prognosis is poor because there is no known effective treatment
