Blood Cells Flashcards
6 yo FN dog with septic arthritis and cellulitis (infected joint and infected skin around the joint). Key CBC results. Low WBC count and low neutrophils. How soon should we repeat the CBC to monitor response to antibiotic therapy for this patient?
She has neutropaenia. She has some bands (immature neutrophils but not higher than normal). Neutrophils last 10 hours in circulation. Marrow storage capacity for neutrophils is 5 days (in health). Marrow can increase neutrophil production in response to an infection 2-3 days- just looking at output.
How soon should we repeat the CBC to monitor response to antibiotic therapy for this patient? 3-4 days would tell us whether the marrow is producing neutrophils properly. 48 hours would tell us if marrow response is hastened. 7 days is too long because we want to see if we have controlled demand before our numbers stabilize because we could miss a severe neutropaenia. 12 hours!! The key number is they only last 10 hours in circulation. Numbers are already lower, storage is already depleted. Am I going to get more severely neutropaenic before the 2-3 day point where the marrow kicks out more? Or 4-6 days when fully matured? Already neutropaenic, we want to ensure animal is not high risk for septacaemia. We want it to be fairly stable from antibiotics and start to rise after a couple of days.
Haematopoiesis
Production of blood cells. Haem- blood, poiesis- to make
Where are blood cells produced? Early embry? Foetus? Neonate? Adult? In disease?
Early embryo- yolk sac Foetus- liver, spleen, bone marrow Neonate- liver and bone marrow Adult- bone marrow Spleen and Liver with disease in adult
So rubriblast starts the maturation, name the rest? How long?
Rubriblast, prorubricyte, rubricyte, metarubricyte, polychromatophil, mature erythrocyte. 3-5 days.
How are senescent erythrocytes removed?
Phagocytosis by macrophages (major route in health), intravascular haemolysis (minor route in health)
Which cells does myelopoiesis include?
Eosinophils, basophils, neutrophils, and monocytes. Myelopoiesis is the production of blood cells in the bone marrow.
What cells do lymphocytes include?
T cells, B cells, and NK cells
Where does lymphopoiesis occur? Facts about lymphocytes.
Thymus and bone marrow. Lymphocytes are capable of mitosis and transformation. Most have life span of 2 weeks. Recirculate via blood and lymphatics.
What does granulopoiesis refer to?
Production of granulocytes (neutrophils, basophils, and eosinophils
What regulates myelopoiesis?
G-CSF (granulocyte colony stimulating factor- cytokine and hormone), GM-CSF (granulocyte macrophage- colony stimulating factor). Increase cell proliferation, differentiation, function
What are the cell line specific cytokines?
IL-6 neutrophils, IL-5 eosinophils, IL-3 basophils. For example, IL-6 (interleukin) is responsible for stimulating production of neutrophils in the bone marrow.
What stimulates bone marrow to release neutrophils?
G-CSF, GM-CSF, C5a, TNF-alpha, TNF-bravo.
Where are neutrophils found?
*Marrow maturation pool, and storage pool (5 days supply). *Blood- circulating pool- free moving in vessels. Marginal pool- loosely adhered to vessels * tissue
What are the functions of neutrophils?
Predominate leukocyte in most species Phagocytic and microbicidal in tissue. Primarily respond to bacterial infections. Role in tissue necrosis, fungal infections, protozoal infections, foreign body reactions. Respond to chemotaxins e.g. C5a, bacterial products, and prostaglandins
What happens to the neutrophil nucleus when it matures? Cytoplasm?
Elongates, condenses, and segments. Cytoplasm loses basophilia and gains secondary granules. Myelocyte–> metamyelocyte–> band–> segmented
What is the life span of a neutrophil in circulation? In tissue?
10 hours in circulation. 24-48 hours in tissue.
What is the life span of an eosinophil in circulation? In tissue?
minutes to hours in circulation. Tissue unknown.
What is the life span of basophils in circulation? In tissue?
6 hours in circulation. Up to 2 weeks in tissue.
Where do leukocytes go when they die?
Phagocytosis by macrophages. Spleen grabs them if they never ended up in the tissue, liver, bone marrow, tissue
What controls eosinophil production? How long does it take eosinophils to mature in bone marrow? What is the blood transit time? Who does not have eosinophils? What is the role of eosinophils?
* IL-5 is major cytokine controlling production (some tumours produce IL-5, so they stimulate eosinophil production for no reason- T cell lymphoma and mast cells as well) * Maturation in marrow 2-6 days * Short blood transit time 1-26 hours * Rare in avians except raptors * kill helminths and have variable role in hypersensitivity
What controls basophil production? How long does it take basophils to mature in marrow? Where are these rare and more common? What is their role?
IL-3. Maturation in marrow 2-3 days. Short blood transit time. Rare in mammals- more common in avians. Role in hypersensitivity, rejection of parasites, and haemostasis.
How fast do monocytes mature in marrow? Transit time in blood? How long do resident tissue macrophages live? Role?
Maturation is rapid 1-2 days (in marrow). Approx 20 hours transit time in blood. Limited recirculating and replication capacity. Resident tissue macrophages live weeks to months. Phagocytic and regulate immune response.
What is thrombopoeisis regulated by? How long do they take to mature? Where do 30-40% of platelets hang out? What is the life span? How are they removed?
Thrombopoeitin from liver, kidney, and marrow stromal cells. Maturation 2-10 days. Released directly into blood. 30-40% sequestered in spleen. Life span 5-9 days. Removal by phagocytosis by macrophages in spleen and liver. Important role in haemostasis.
Leukogram
Total leukocyte count, individual leukocyte count, leukocyte morphology (automated or manual)
What is a Complete Blood Count (CBC)?
Leukogram, erythrogram, thrombogram, TP and sample appearance
What are the leukocytes found in circulation?
Lymphocytes, basophils, eosinophils, monocytes, neutrophils
What is a marginating pool vs. circulating pool?
Marginating pool = loosely adherent to vessel Circulating pool= free flowing in vessel
How does the bone marrow respond to inflammation?
* Release of neutrophils from storage pool (neutrophilia) * release of neutrophils from maturation pool –> Left shift in blood * increased neutrophil production–> left shift in marrow * accelerated neutrophil maturation–> toxic change
Neutrophilia with stress response
Corticosteroid driven. High cortisol levels causes a change int the leukogram. It causes neutrophilia. A shift (change)- the leukocytes are blocked from migrating out of the tissue- less marginated. Quite a large jump with neutrophils- high cortisol level. Cortisol is a natural anti-inflammatory.
Only a little release from storage pool, shift from marginal pool to circulating pool, reduced emigration from blood to tissue
What is a cause of neutrophilia in young animals (especially cats, why?)?
Excitement- adrenaline mediated & young animals
Kittens especially because they have a high marginated count of neutrophils.
No left shift. No toxic change. Just an increase of mature neutrophils.
What are some causes of neutropenia?
Overwhelming inflammatory demand, transient margination (endotoxaemia), bone marrow disease (not producing neutrophils because of some sort of disease process- lots of examples- marrow infiltrated with tumour cells, end stage lymphoma- no room to make neutrophils, insult that causes damage to bone marrow- because fibrosed and full of fat without the haemopoeitic tissue; chemotherapy- temporarily shuts down production), immune mediated destruction (body can attack neutrophils or thrombocytes, and of course red cells, etc. can be separate event or at the same time)
Endotoxaemia (some nasty infection somewhere, won’t rebound without having tissue inflammation)- because the neutrophils are getting sticky to the vessels. Shift into the marginating pool instead of the circulating pool. So they are not in the middle where we are blood sampling. 6-12 hours later, they can then become back to normal.
What is a neutrophil left shift?
Increased immature neutrophils in blood. * usually bands * regenerative left shift (mature > immature) * degenerative left shift (immature > mature)
If you see a degenerative left shift, poor prognosis- animal more likely to succumb to infection. Animal’s bone marrow can’t keep up.
(if you are see myeloblasts, you should be worried about leukaemia- such an early stage)
What is regenerative left shift?
Mature > immature
What is degenerative left shift?
Immature > mature
If you have a high WBC count, high neutrophil count and high bands count, what does this mean? Or it can also be just high bands count and low or normal neutrophils, bands, metamyelocytes. (recall: you won’t get a band count unless someone has looked at the smear)
What is bands are about the same as our neutrophils. Add up bands and metamyleocytes and compare to neutrophil count. If they add up to more than?
Neutrophil left shift
- second question: degenerative.
What processes in a patient cause a neutrophil left shift?
* Indicates inflammation = high demand for neutrophils * reflects release from maturation pool * can also occur with myeloproliferative disease e.g. chronic myeloid leukaemia
What causes a degenerative left shift?
Indicates overwhelming inflammatory demand. More guarded prognosis.
Be careful with cows as they have a small storage pool. So if you see degenerative left shift with a cow, there is still some sort of infection, but not as poor of a prognosis as a dog.
Cattle with acute inflammation can show neutropenia with severe left shift, why?
They have a small neutrophil storage pool
What is the life span of lymphocytes?
Weeks to years (depending on their function. For example, the memory cells hang around for a long time).
What causes lymphocytosis?
Chronic antigenic stimulation (vaccination), adrenaline/ excitement (young animals: <12 months, often under 6-8 months, rare in adults. Horses especially)- same process that causes neutrophils to move into circulating pool does the same with lymphocytes (so often neutrophilia and lymphocytosis), lymphoid neoplasia, hypoadrenocorticism (low cortisol levels)
What causes lymphopenia?
* Glucocorticoids/ Stress (high cortisol levels. If it doesn’t have lymphopenia, probably not a stress leukogram. reduced release from LN and spleen, lympholysis of uncommitted Lymphocytes- particularly at high doses) - recall: Cortisol reduces inflammation
* Acute inflammation- is it directly inflamm. process or stress? We don’t know, but we usually see it.
* Loss of lymph fluid- chylothorax, enteric neoplasia, protein losing enteropathy (because we are not getting that recirculation of lymphocytes back into the blood)
What are some functions of monocytes?
* Provide macrophages to tissue
* Phagocytosis- foreign material, dead cells, less efficient for microbes
* Immune regulation- source of cytokine & chemotactic factors, present antigen to T lymphocytes, perform antibody dependent cytotoxicity
What are some causes of monocytosis?
* Acute or chronic inflammation
* Glucocorticoids/ Stress (only seen in dogs)
* Myeloproliferative disease e.g. myeloid leukaemia
What are some causes of monocytopenia?
Clinically insignificant as many healthy animals have very low numbers of monocytes in the blood
What are the functions of eosinophils?
* Kill helminths * Suppress hypersensitivity * Promote inflammation (allergies)
What are some causes of eosinophilia?
* Worms- parasitic infection- endo and ectoparasites * Wheezes and whelts- allergies & hypersensitivity * Weird diseases (paraneoplasic- lymphoma, mast cell tumour; hyperesoinophilic syndrome; eosinophilic leukaemia; eosinophilic granuloma complex)
What are some causes of eosinopenia?
* Glucocorticoids/ Stress (lymphopenia, mature neutrophilia.. may help us decide it is a stress leukogram)
* Can be incidental
What are the functions of basophils?
* Histamine release
* Promote lipid metabolism
* Haemostasis
* Parasite control
What are some causes of basophilia?
* Stress in birds * often accompanies eosinophilia * worms- parasitic infection- endo and ecto parasites * Wheezes & whelts- allergies/ hypersensitivities * Weird diseases- paraneoplastic (lymphoma, mast cell tumour); hypereosinophilic syndrome; basophilic leukaemia; myeloproliferative diseases e.g. polycythaemia vera
What about Basopenia?
Too few in health to recognize basopenia.
What are the main differentials for a neutropenia?
Acute overwhelming suppurative inflammation, endotoxaemia, dereased production/ marrow disease, drugs causing myelotoxicity
Neutrophil
Monocyte
Eosinophil
Lymphocyte
Basophil
What cells are these?
Left to right. Erythrocyte, platelet (activated), and leukocyte (can’t tell what kind). Scanning micrograph (?)
What is the base stem cell for haematopoiesis? What are the next two that it can turn into?
Pluripotent stem cell. Either Myeloid stem cell (either granulocytes or monocyte). OR Lymphoid stem cell- T lymphocyte or B lymphocyte.
What are megakaryocytes?
Make our platelets.
What happens as erythrocytes mature?
Haemoglobin increases, nucleus condenses, and then is extruded.
Are monocytes granulocytes? What is one way to help identify monocytes?
No. Vacuoles.
What cell is this?
Megakaryocyte
What might this hypersegementation of a neutrophil indicate?
Glucocorticoid/ Stress. Corticoid steroid response. Neutrophils are able to age longer in the blood. Hypersegmented = right shifting. (stress response going on for more than a day- recall: neutrophils only last about 10 hours in circulation)
If you saw these cells, what is a possible diagnosis?
Acute Myeloid Leukaemia. this is an immature/ blastic cell. Normal you would see about 20 cells, but they are all over the place. Pinky-red granules, big and round in cytoplasm.
Monocyte
Monocyte
Monocyte
Cat eosinophil
Horse eosinophil
Dog eosinophil
Dog basophil
Cat basophil
Regenerative or degenerative?
Degenerative
Chronic Inflammatory Leukogram
Overwhelming Inflammatory Leukogram
Severe Acute Inflammatory Leukogram
Acute Inflammatory Leukogram
Granulocytic Hypoplasia Serial Leukograms.
No bands. At first looking for inflammation but then by day 7, you realize primary bone marrow disease.
Rubricyte (darker chromatin to a lymphocyte- granular chromatin as well)
Horse eosinophil
Horse monocyte
Horse lymphocyte
Horse neutrophil.
Horse basophil.
Dohle Bodies (blue cytoplasm- basophilic)
Toxic neutrophil.
Toxic neutrophil. Basophilic.
Toxic neutrophil. Toxic granulation. Sepsis likely.
Ring form neutrophils. This marrow is struggling with demand.
Rabbit heterophil
Snake heterophil
Birman cat neutrophil and eosinophil
Band neutrophils. Even the S. Toxic neutrophils (blue)
Botriod nucleus. Seen with heat stroke. Hypersegementation where links fuse in the center.
Bar body. Tells us it is a female animal. A little drumstick. Dohle bodies with toxic change.
Left- neutrophil- some vacuoles.
Right- monocyte or band.
Left- Toxic neutrophil (may be segmented, may be band)
Middle- Band
Right- lymphocyte or rubricyte or metamyleocyte or myleocyte or monocyte. Pattern of chromatin looks very similar to neutrophil. Look at cytoplasm- looks similar to neutrophils as well. Most likely myleocyte with toxic change (round nucleus)- looks like it is about to indent.
Left- monocyte (vacuoles)- nucleus is strangely shaped but that’s okay because typical of monocytes
Right- granular lymphocyte (low numbers in health)- going to be either a T cell or NK cell.
Reactive lymphocytes. Larger than normal nucleus. Clear zone adjacent to the nucleus as well (most likely thinking about producing an Ab- may see in recently vaccinated animal- increased numbers in inflammation as well). Lymphocytes responding to antigenic stimulation.
Left lymphocytes- normal. Right lymphocyte reactive.
Monocytes eating red cells. This could happen with IMHA (if see with spherocytes, esp.). Or a blood transfusion reaction.
Erythrophagia.
Fine chromatin and nucleioli. Blasts- really immature forms of cells. You should not see these in the blood. Myleoblast, monoblast or lymphoblast. If you see more than one, you would think of leukaemia.
Mast cells. Should not be in the blood. Round nucleus vs. basophil’s ribbony nucleus. If they don’t have inflammatory disease, worry about mast cell neoplasia.
Swollen neutrophils. Degenerate neutrophils. Neutrophil that has phagocytosed bacteria.
Dohle bodies. But they could also be Distemper Virus inclusions. However erythrocytes have the same blue inclusions, so diagnosed with Distemper.
Could be stress leukogram but it has bands. Left shifted. Not leukaemoid (not above 150). Acute Inflammation. (Regenerative left shift, not neutropenic so not overwhelming)
