Hematology 1 EOR Exam Review

Earliest hematopoietic cell

pluripotential stem cell

Earliest erythroid cell

pronormoblast rubriblast

Progenitor stem cells

Committed to myeloid or lymphoid

Hematopoesis

The process of formation and development of the various types of blood cells and other formed elements

Where does fetal hematopoiesis occur?

yolk sac, spleen, liver

Where does postnatal hematopoiesis occur?

bone marrow

Cytokines

can influence stem cells with multilineage potential, influence differentiation of specific cell types, some prevent apoptosis

apoptosis

programmed cell death

What gives blood cell cytoplasm its blue color

RNA that is still present

What changes occur to cells as they mature

1. The size decreases

2. Cell diameter decreases

3. The N/C ratio decreases

4. Nuclear color changes from purple to red to dark blue

5. Nuclear chromatin becomes coarser, clumped, and condensed nucleoli disappear

6. Staining: blue to less blue

7. In RBCs, nucleus becomes fully condensed and is ejected

8. In granulocytes, nuclear shape changes and nucleus becomes segmented

Diapedesis

process by which normoblasts transverse between or through the endothelial cells of the BM sinus

Myelopoiesis

Maturation of neutrophils, basophils, and eosinophils

Mitotic pools

in bone marrow capable of division

Storage pools

in bone marrow NOT capable of division 

Life span of RBCs

120 days

Life span of neutrophils in PB

6-10 hours

Life span of neutrophils in tissues

Lifespan depends on whether they are responding to inflammation which will prolong their lifespan

Life span of eosinophils

18 hour half life

Life span of macrophages

depends on whether they are responding to inflammation or infection or are resident macrophages like kupffer cells which have a life span of 21 days, inflammatory macrophages have a life span measured in hours

Reference range of WBCs

4.5-11.5 x 10^9 / L

Reference range of RBCs for males

4.6-6.0 x 10^12 / L

Reference range of RBCs for females

4.0-5.4 x 10^12 / L

Reference range of Hgb for males

14.0-18.0 g/dL

Reference range of Hgb for females

12.0-16.0 g/dL

Reference range of Hct for males

40-54%

Reference range of Hct for females

35-49%

Reference range for platelet count

150-450 × 10^9 / L

Reference range for reticulocytes in adults

0.5-1.5%

Reference range for reticulocytes in newborns

2.0-6.0%

Absolute reticulocyte count reference range

25,000-75,000 / uL

ESR reference range males up to age 50

0-15 mm

ESR reference range males over age 50

0-20 mm

ESR reference range females up to age 50

0-20 mm

ESR reference range females over age 50

0-30 mm

Which growth factors are involved in megakaryopoiesis?

TPO is the primary regulator

Where is erythropoietin produced and what effect does it have on RBCs

Synthesized in the kidneys

Stimulates RBC production, it signals progenitor cells to survive, proliferate and mature into RBCs. Binds to receptors on erythroid progenitor cells in the bone marrow telling them to divide and mature into new RBCs

 Which cells are involved in antigenic stimulation

Involves antigen presenting cells like dendritic cells, macrophages, and B cells, which process and present antigens to T cells and activate B cells leading to specific immune responses

Plasma cells origin and function

Originate from B lymphocytes that have been immunologically stimulated by antigens

Their primary function is to generate antibodies (immunoglobulins)

Function of neutrophils

the immune systems first responders primarily fighting bacterial and fungal infections by phagocytosis

Function of platelets

to stop bleeding by forming clots at sites of vascular injury. form a plug at the site of injury and take part in the clotting process.

Function of eosinophils

fights parasitic infections and allergic reactions

Function of basophils

trigger inflammation and allergic responses by releasing chemicals like histamine, fighting parasites, and bridging innate and adaptive immunity

Function of lymphocytes

form the immune system's memory, fighting infections by identifying and neutralizing pathogens. B cells, T cells, and natural killer cells

Function of macrophages

engulf pathogens and debris, present antigens to activate other immune cells (innate and adaptive immunity), and release cytokines to signal infections

Should blasts be seen on a peripheral blood smear?

BLASTS should NEVER be seen on PBS. If a blast is seen, a cause must be determined

Megakaryopoiesis

platelet formation

Where are 30% of peripheral blood platelets sequestered?

In the spleen

Endomitosis

A type of cell division where chromosomes replicate but the cell itself fails to divide, resulting in a single large polyploid cell with multiple sets of chromosomes. The megakaryocyte is the ONLY cell that divides by dndomitosis. Only the nucleus divides with no cell division.

Embden-Meyerhof Pathway

RBCs generate energy almost exclusively through the anaerobic breakdown of glucose (90% of the energy generated)

Hexose monophosphate shunt (aerobic glycolysis)

detoxifies accumulated peroxide, diverts G6P to PP by the action of G6PD

protects RVCs from oxidants, uses G6PD

Methemoglobin reductase pathway

heme iron is constantly exposed to oxygen, and oxidizing agent, methemoglobin results from the oxidation of heme iron from the ferrous to the ferric state (not functional hemoglobin)

maintains iron in the ferrous state

Luebering rapaport shunt

generates 2,3 BPG which regulates oxygen delivery to tissues

Hemoglobin

main component of RBCs, transports O2 and CO2

RBC membrane deformability

Able to stretch undamaged up to 2.5 times their diameter

RBC membrane cation pump damage

If cation pump is damaged the cells swell and rupture (spherocytes)

What is the RBC membrane mostly made of?

Lipids

Transferrin

carries iron to developing RBCs

Glycophorin

integral protein

accounts for most of the membrane (sialic acid) give RBCs its negative charge

location of many RBC antigens

Spectrin

peripheral protein

strengthens membrane and preserves deformability

Primary (azurophilic) granules

formed during the promyelocyte stage, last to be released. Contain powerful enzymes and antimicrobial peptides

Secondary granules

formed during myelocyte and metamyelocyte stages, third to be released. Store lactoferrin, collagenase and components for the respiratory burst

Neutrophilic granules

storage vesicles packed with powerful enzymes, antimicrobial peptides, and signaling molecules that enable neutrophils to rapidly destroy pathogens, orchestrate inflammation, and initiate tissue repair

Oxygen dissociation curve shift to the right factors

release of oxygen, decrease in HGBs affinity for oxygen, decrease in pH, increase in 2,3 BPG, increase in temperature

tense form of Hgb, deoxyhemoglobin

Oxygen dissociation curve shift to the right conditions

high fever, acidosis, conditions causing hypoxia (high altitudes, pulmonary insufficiency, congestive heart failure, severe anemia)

Oxygen dissociation curve shift to the left factors

uptake of oxygen, increase in HGBs affinity for oxygen, increase in pH, decrease in 2,3 BPG, decrease in temperature

relaxed form of Hgb, oxyhemoglobin

Oxygen dissociation curve shift to the left conditions

multiple transfusions with old blood, alkalosis, Hb F, methemoglobin, carboxyhemoglobin, hyperventilation

Hemoglobin structure

• 4 heme groups

• Ferrous state iron is central ion

• 4 globins

  • 2 alphas and 2 nonalphas

• Biosynthesis of heme occurs in the mitochondria and cytoplasm of pronormoblasts - reticulocytes in the BM

• Transferrin deliver iron to the membrane of RBC precursors 

Adult hemoglobins

Hb-A (97%) and Hb-A2 (1.5-3.2%)

Hb-A chains

2 alpha and 2 beta chains

Hb-A2 chains

2 alpha and 2 delta chains

Fetal hemoglobin

Hb-F

Hb-F chains

2 alpha and 2 gamma chains

Newborn hemoglobin percentages

• Hb F - 60-90%

• Hb A - 10-40%

1 year - adult hemoglobin percentages

• Hb F - 0-2%

• Hb A2 - 0-3.5%

• Hb A - 95%

Hemoglobins found in embryos

• Gower 1

• Gower 2

• Portland

What is the rate limiting step in the production of heme?

glycine and succinyl-CoA -> ALA

2,3 BPG and oxygen affinity

As 2,3 BPG increase oxygen affinity decreases and O2 is unloaded from Hb

How is Hgb synthesis normally stimulated?

By tissue hypoxia - decreased O2 stimulates an increase in EPO and thus, an increase in RBCs

Tense form of hemoglobin

space is widened between beta chains in Hb and is bound to 2,3 BPG, anionic salt bridges form between beta chains, lower affinity for oxygen

Relaxed form of hemoglobin

when Hb takes up oxygen salt bridges are broken and 2,3 BPG is expelled

Making a peripheral blood smear

• Slide at a 30-45 degrees angle, if the hematocrit is higher the angle should be lowered to 25 degrees

• Smear is ⅔ to ¾ length of the slide, have a rounded feathered edge

• Smears should be dried as quickly as possible to avoid drying artifacts, do not blow breath on the slide it is counterproductive

• Wright stain used for blood and bone marrow smears

• Free methylene blue stains RNA

• Free eosin stains hemoglobin and eosinophilic granules

• RBC gray, WBCs too dark, eosinophil granules are grey = stain or buffer is too alkaline, inadequate rinsing, prolonged staining, or heparinized blood sample

• RBCs are too pale, WBCs barely visible = stain or buffer too acidic, under buffering, over rinsing

Platelet satellitism

Creates falsely increased WBC count

The specimen should be redrawn in sodium citrate tube

Hemacytometer

• Diluent to preserve the cell, for WBC it must also destroy the RBCs

• Count the cells touching the left and top lines

Hemoglobin measurement sources of error

Lipemia, Hgb S or C

Specimen used for packed cell volume

Spun hematocrit

Erythrocyte Sedimentation Rate (ESR)

• distance RBCs fall in an hour

• Sources of error: increased temperature, air bubbles, tube tilting

• Non-specific indicator of inflammation or infection

Manual reticulocyte count and BM activity

Manual reticulocyte count reflects erythropoietic activity of bone marrow

Rule of Three

• Hemoglobin = 3X RBC count

• Hematocrit = 3X hemoglobin

• Only applies when RBCs are normal size and hemoglobin content

Normal percentage of neutrophils

40-70%

Normal percentage of lymphocytes

20-40%

Normal percentage of monocytes

2-11%

Normal percentage of eosinophils

1-4%

Normal percentage of basophils

0.5-1%

Platelet estimate formula

count number of platelets in 10 fields, take average and multiply by 20,000

Corrected WBC count formula

 WBC x 100 / NRBC in 100 WBCs + 100

Order of draw for phlebotomy

blue top tube then lavender top tube

The MOST IMPORTANT step in collection of a blood specimen

Patient identification

Aplastic anemia

• Abnormal or damaged stem cells

• Symptoms due to: anemia, thrombocytopenia, leukopenia

• Anemia is typically normocytic or macrocytic

• Hemoglobin usually less than 10

• MCV is increased or normal

• Reticulocyte count is decreased 

• Bone marrow: severely hypocellular 

• Serum iron and ferritin increased

• Platelet decreased

• Inherited fanconi anemia: alpha fetoproteins and fetal hemoglobin are increased

• Treatment: supportive, immunosuppressive therapy, stem cell transplantation

Paroxysmal Nocturnal Hemoglobinuria (PNH)

• Stem cell mutation, rare chronic intravascular anemia

• Deficiency of decay accelerating factor (DAF) or CD59 and CD55

• Hemolytic anemia, thrombosis, and bone marrow failure

• All cell lines have the mutation and are affected

• Hemoglobinuria, hemoglobinemia, decreased serum haptoglobin, increased serum indirect bilirubin and lactate dehydrogenase, hemosiderinuria

• Stain urine sediment with prussian blue (iron stain) to identify iron imbedded in epithelial cells 

• The only cure is bone marrow transplant

Hereditary Spherocytosis

• Spectrin deficiency of RBC membrane

• RBC progressively losses membrane and acquires a decreased surface to volume ratio and spheroidal shape

• Spleen is the culprit of the destruction 

• MCV normal or slightly decreased

• MCHC increased

• Reticulocytosis

• NRBC and polychromasia depending on degree of destruction

• Increased osmotic fragility, they lyse in less hypotonic(more hypertonic) solutions

• DAT to detect antibodies on the RBC membrane will help to distinguish between inherited and acquired

• Splenectomy will remove the site of destruction