Immunology/Hematology Flashcards by Leonie Bertram

What is the normal platelet number per HPF in dogs?

8-15 platelets/HPF (120 - 225K/uL)

*Each platelet = 15,000/ platelets/uL

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What is methemoglobin?

A type of hemoglobin that the iron on the heme has been oxidized from ferrous (Fe2+) to ferric (Fe3+)

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When there are >30% methemoglobins in the circulation, what does the pulse oximeter usually show? Why?

85% (even if PaO2 is high)
Methemoglobins absorb both wavelengths of light very well.

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What are the two type of reticulocytes in cats? Which one can be seen up to 10% in healthy cats?

Aggregate reticulocytes & Punctate reticulocytes

Punctate reticulocytes can be seen in healthy cats
* Aggregate forms are released from the marrow and, after approximately 12 hours, develop into punctate forms that persist in the circulation for 9–20 days.

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Where does ferritin exist and what is its function?

Ferritin exists in all cells
It stores iron and acts as a reservoir to prevent excessive intracellular ion causing cell damage.

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What is the function of Hepcidin?

It is secreted by hepatocytes and inhibits iron export from enterocytes, macrophages, and hepatocytes.

↑ production during iron overload

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What is the function of transferrin?

Transport iron

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For Transferrin and Ferritin, which one is positive acute phase protein and which one is negative acute phase protein?

Transferrin: negative acute phase protein
Ferritin: positive acute phase protein

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What is the lifespan for canine and feline RBCs?

Dog: 120 days
Cat: 80 days

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What is the lifespan of platelets?

5-7 days

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What is the lifespan of neutrophils?

< 24 hours

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What is the function of haptoglobin?

It binds to free hemoglobin in the circulation

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True or False: Hemoglobin has 2 𝜶 globins and 2 𝜷 globins, all of which contains heme molecules.

True

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Which iron can bind to oxygen, ferric or ferrous?

Ferrous (Fe2+) can bind to oxygen
Ferric (Fe3+) cannot

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What does 2,3-DPG do?

It decreases hemoglobin affinity to oxygen.

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What is Heinz bodies?

Damaged hemoglobins (usually from oxidative damage)

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What is phosphofructokinase (PFK) deficiency and what is the treatment?

Periodic intravascular hemolysis and hemoglobinuria associated with strenuous exercise or stress-induced hyperventilation causing respiratory alkalosis

Treatment: exercise restriction

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What is pyruvate kinase (PK) deficiency?

Decreased ATP availability due to lacking of PK → hemolysis
Moderate to severe macrocytic hypochromic anemia with marked reticulocytosis → myelofibrosis → non- regenerative anemia

Worse prognosis compared to PFK deficiency

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List 10 causes of hemolysis.

1) Primary IMHA
2) Mycoplasma haemofelis infection
3) DIC
4) Splenic neoplasia
5) Hypophosphatemia
6) IV hypotonic fluid bolus
7) Phosphofructokinase deficiency
8) Pyruvate kinase deficiency
9) Uremic-hemolytic syndrome
10) Onion ingestion
11) Zinc, copper toxicity

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Which type of hypersensitivity is associated with IMHA?

Type II

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Describe neonatal isoerythrolysis.

It happens in kittens - when type B queen mated to a type A male and the kitten is type AB or A.

When kitten is nursed with the queen’s colostrum, the can absorb the antibodies against type A epitope. About 12-24 hours after colostrum ingestion, the antibodies against type A epitope will be in the circulation and attack kitten’s RBCs

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What is the equation for corrected reticulocytes?

Corrected reticulocytes = Measured reticulocytes x (PCV/N)

*In dogs, N = 45; in cats, N = 37)

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After a BM insult, which cell line decrease will be observed first?

Granulocytes → Neutropenia (5-6 days later)
Thrombocytopenia (8-10 days)

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What is the function of hepcidin?

It regulates the iron metabolism and availability.
Increased hepcidin → decreased iron availability
Positive acute phase protein

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What is the definitive of RBC regeneration in dogs?

Reticulocytes > 60K/uL

What is the common sequela of Pyruvate kinase (PK) deficiency?

Myelofibrosis Osteosclerosis Hemosiderosis-induced hepatic failure or bone marrow failure

Does canine and feline RBC contain mitochondria?

What is normal RBC:WBC ratio?

500:1

How to calculate HCT?

HCT = MCV x RBC/10

Name 3 oxidizing agents in the neutrophils

Superoxide (O2−) Hydrogen peroxide (H2O2) Hydroxyl ion (OH ) * one of the lysosomal enzymes, myeloperoxidase, catalyzes the reaction between H2O2 and Cl- to form hypochlorite, which is exceedingly bactericidal.

During inflammation, what is the first line to four line defense mechanism of the body.

1) Tissue macrophage 2) Neutrophil Invasion of the Inflamed Area 3) Second Macrophage Invasion Into the Inflamed Tissue 4) Increased Production of Granulocytes and Monocytes by Bone Marrow

How many days does it take for the newly formed granulocytes and monocytes reach the stage of leaving the bone marrow?

3-4 days

What are the 5 factors that are mainly responsible in control of macrophage response (to stimulate BM)?

1) TNF-𝜶 2) IL-1 3) GM-CSF 4) G-CSF 5) M-CSF

Name two cells that can release eosinophil chemotactic factors.

Mast cells Basophils

Name 4 substances mast cells (and basophils) release during inflammation.

Heparin Histamine Bradykinin Serotonin

Name 4 aspects of innate immunity.

1) Phagocytosis of bacteria by neutrophils & lymphocytes 2) Stomach acid and digestive enzymes destroy the swallow organisms 3) Skin as a barrier to invaded organisms 4) Certain chemicals in the blood that attach to foreign organisms or toxins and destroy them (e.g. complement complex, lysosome, basic polypeptides, natural killer lymphocytes)

What are the two main types of acquired/adaptive immunity?

Humoral immunity (B cell immunity) Cell-mediated immunity (T cell immunity)

Fill out the blank.

In normal body, how many percentages of immunoglobulins are IgG?

75%

Name four ways of antibodies destroy antigens directly.

1) Agglutination 2) Precipitation 3) Neutralization 4) Lysis

Write down the classic pathway of complement.

Which complement protein cause opsonization of bacteria?

C3b

What is the complement protein compose the membrane attack complex (MAC)?

C5b6789 * MAC inserts itself into lipid bilayers and makes holes on the cell → cell lysis

Which complement protein initiate chemotaxis of neutrophils and macrophages?

C5a

Name three complement protein fragments that can activate mast cells and basophils.

C3a C4a C5a

What are the three major antigen presenting cells in the body and what is the site where the antigen bind to?

Macrophage, B lymphocyte, dendritic cell (accessory cell) MHC protein (Major histocompatibility complex)

What are the two types of MHC protein and what is the main difference?

MHC 1 protein - present to cytotoxic T cells MHC 2 protein - present to T helper cells

Which type of T cells is the most abundant in the body?

T helper cells

Which interleukin has strong positive effect for the proliferation of cytotoxic T cells and regulatory T cells?

IL-2

Which three interleukins are called B-cell stimulating factors or B-cell growth factors?

IL-4, IL-5, IL-6

True or False: CD4 T cells are mainly cytokine-secreting helper cells, whereas CD8 T cells are mainly cytotoxic killer cells.

True

True or False: CD4 T cells can be divided into two major types. Type 1 (Th1) helper T cells secrete interleukin-2 and interferon-𝛄 but not interleukin-4, 5, or 6. Type 2 (Th2) helper T cells secrete interleukin-4, 5, 6, and 10 but not interleukin-2 or interferon-𝛄.

True

What are the three complement pathways? What is the activator for each pathway?

1) Classic pathway - pathogen, antibody-antigen complex to C1 2) Mannan-binding lectin pathway - PAMP recognized by lectin (e.g. mannose-containing carbohydrates on bacteria or viruses) 3) Alternative pathway - spontaneously activated complement component (e.g. pathogens)

How many spherocytes/x100 oil immersion field support immune-mediated destruction of RBC?

> 5 spherocytes/x100 oil immersion field (Sen: 63%; Spe 95%)

In the ACVIM Consensus Statement of IMHA, what are the 4 evidences of hemolysis?

Hyperbilirubinemia Ghost cells Hemoglobinemia Hemoglobinuria

True or False: Saline agglutination testing performed by mixing 4 drops of saline with 1 drop of blood has a reported specificity of 100% for IMHA in dogs.

True

True or False: There is a high level of evidence that immune-mediated destruction of erythrocytes contributes to anemia in dogs infected with B. canis

False B. gibsoni (from fighting)

In the ACVIM Consensus Statement of IMHA, it states that the evidence of M. haemofelis causing IMHA in cats is high.

True

What is the non-associative cause of IMHA? What about associative?

Non-associative: primary, cryptogenic Associative: secondary

True or False: According to the ACVIM Consensus Statement of the treatment of IMHA, fresh RBC or at least no older than 7-10 days is recommended for use in dogs with IMHA.

True

According to the ACVIM Consensus Statement of the treatment of IMHA, what is the recommended dose for prednisone? If the dog is responding to the tx and is on > 2 mg/kg/d, when should you taper it?

2-3 mg/kg/d or 50-60 mg/m^/d (for dogs > 25 kg) * Dex SP 0.2-0.4 mg/kg/d if cannot tolerate oral med After 1-2 week

According to the ACVIM Consensus Statement of the treatment of IMHA, what are the 4 conditions when second immunosuppressant is recommended?

1) Severe, life-threatening IMHA 2) First 7 days the HCT decreases ≥ 5% in 24 hours (on pred) 3) Dependent on blood transfusion after 7 days (on pred) 4) Severe side effects from prednisone

List 4 drugs as second immunosuppressant for canine IMHA and their dose.

Azathioprine - 2 mg/kg or 50 mg/m2 PO q24h Mycophenolate - 8-12 mg/kg PO q12h Cyclosporine - 5 mg/kg PO q12h Leflunomide - 2 mg/kg PO q24h * They recommend cyclophosphamide not be administered to dogs with IMHA.

According to the ACVIM Consensus Statement of the treatment of IMHA, what is the recommended intervention if the dog does not respond to second immunosuppressant after 7 days?

IVIG 0.5-1g/kg single dose

According to the ACVIM Consensus Statement of the treatment of IMHA, if dog's PCV/Hct has remained stable and >30% for 2 weeks after commencing treatment, what is the recommended tapering plan?

Taper prednisone by 25%, and by 25% every 3 weeks thereafter * If there is a second immunosuppressant → don't change the dose of that drug

According to the ACVIM Consensus Statement of the treatment of IMHA, what is the recommended management for asymptomatic neutropenic patients?

If the neutrophil count is between 1000 and 3000 cells/μL → no antibiotics unless other independent risk factors for infection are present If the neutrophil count is <1000 cells/μL → prophylactic antibiotics

What is the relapse rate for IMHA?

11-15%

List 5 complications of IVIG administration.

1) Anaphylaxis 2) Acute kidney injury 3) Hypotension 4) Fluid overload 5) Thromboembolism

What is the recommended dose for IVIG?

0.5 - 1.5 g/kg IV over 4-8 hours

How does hepcidin affect iron?

Decreased iron availability - Decrease GI absorption - Prevent iron release from hepatocytes and macrophages - Increase cellular internalization and degradation of ferroportin

Is ferritin a positive or negative acute phase protein? What does it do? What about transferrin?

Ferritin - positive acute phase protein - blood protein that contains iron Transferrin - negative acute phase protein - main protein in blood that binds and transports iron

Name 2 poor prognostic indicators for IMHA and ITP.

IMHA HighBUN level Hyperbilirubinemia ITP High BUN level Melena

What is a triad of symptoms for hemolytic-uremic syndrome? What is the cause?

Thrombocytopenia Acute renal impairment (e.g. glomerular necrosis) Microangiopathic hemolytic anemia It is caused by Shiga-like toxin produced by E. coli (typical from), other bacteria, medication, immune processes

What metal on the pennies minted after 1982 can lead to hemolysis?

Copper

In cats, nonregenerative anemias with macrocytic normochromic red blood cells may be suggestive of what type of infection?

FeLV

In patients with IMHA, there are extravascular hemolysis and intravascular hemolysis. What immunoglobulin is associated with each and how does the hemolysis occur?

Extravascular hemolysis - IgG - IgG-RBC complex is cleared through the reticuloendothelial system Intravascular hemolysis - IgM - IgM-RBC complex activates C3 and membrane attack complexes, induces the classical complement pathway, and results in intravascular hemolysis.