RBC Morphology and Blood groups

Iron in the blood:

Iron is transported into blood, stored in bone erythrocytes and macrophages in bone marrow, spleen and liver

effected by anemia and cytokines

What is the function of iron in the red blood cell?

Oxygen transport

Transferrin

negative acute protein phase

Cytokines decrease transferrin

How is Iron transported?

transported plasma bound to transferrin

What is the storage form of iron?

ferritin and hemosiderin

cytokines increase Fe stores

Characteristics of RBCs

Anucleate

Have repelling forces

Anaerobic metabolism

Morphologic Features of Erythrocytes

Biconcave shape which creates a central pallor and high surface:volume ratio

Blood Groups (Types)

Glycolipid & glycoprotein RBC surface antigens

Inherited, Immunogenic, Species-specific

Importance of Blood Groups in veterinary medicine

Blood transfusions

Diagnosis and characterization of disease

Parentage testing

Forensic science

Feline RBCs

Central pallor is not prominent

Lifespan in circulation is ~75 days

Morphology of Feline RBCs

Feline Blood Type A

Most common

have naturally occurring antibodies

Low titer anti-B hemagglutinins and hemolysins

Feline Blood Type B

Higher titer anti-A hemagglutinins and hemolysins

Characteristics of Canine RBCs

Prominent central pallor

lifespan in circulation ~120 days

Canine Blood type DEA 1.1

most antigenic and should be avoided

Canine Blood type DEA 4 positive

Universal donor

lack other antigens; however transfusion reactions can occur after multiple exposure(DEA 4 neg to pos) and DEA 1.1 negative dogs

Canine Blood type groups(Dog erythrocyte antigen)

DEA 1.1, 1.2, 1.3, DEA 4, DEA 3, 5, DEA 7, Dai, Kai

Morphology of canine RBCs

?????

Characteristics of Equine RBCs

Rouleaux formation – stack of coins

Lifespan in circulation is about 160 days

Equine blood groups(A,C,D,K,P,Q,U)

Blood group genes produce antigenic sites called factors, 30 + factors found (usually "a")

Donors need to be negative for antibodies to the factors: Most immunogenic: Aa, and Qa

Morphology of Equine RBCs

Bovine RBCs

Medium sized RBCs

MCV= 60 FL

Lifespan in circulation is about 140 days

Bovine blood groups

11 genetic systems recognized

Most important: EAJ-system

Serum and tissue antigen

Camelids RBCS

elliptical RBCS

Lack a central pallor

Blood groups(A,B,C,D,F)

Morphology of Camelid RBC

Morphology of Deer RBCs

Exotic RBCs

Large elliptical cell

Nucleated RBCs

Aerobic metabolism

Different exotic species lifespan in circulation

Avian 28 days

Amphibians 800 days

What is the best course of action in a neonatal foal that has clinical signs of neonatal Isoerythrolysis (moderate hemolytic anemia)?

D. Withhold colostrum from the foal

What are important characteristics of RBC morphology?

Density and distribution

Shape

Size

Color

Rouleau: roll of coins

cells lose repelling force

Seen mostly with hyperglobulinemia and/or hyperfibrinogenemia

Usually due to inflammation &/or dehydration

Rouleau morphology

Equine erythrocytes form rouleaux easily; even in healthy horses

Agglutination Formation

antibodies form bridges between RBCs

Significance of agglutination

Immune-mediated anemias

Interferes with cell counting and sizing methods

Clumps seen as large RBCs(decrease [RBC] & increase MCV)

Saline agglutination test (SAT)

Failure to disperse= IMHA(Immune-Mediated Hemolytic Anemia)

Dispersion = dehydration and/ or inflammation

Anisocytosis

due to presence of macrocytes, discocytes, microcytes

Significance: Regenerative anemia

morphology of Anisocytosis

Macrocytosis Formation:

incomplete maturation or skipped cell division

Macrocytosis significance

Regenerative anemia

Correlates with ↑ Mean Cell Volume (MCV)

Best evidence of RBC regeneration in horses

Poodle dyscrasia

Morphology of Macrocytosis

Microcytosis

Results from increase in cell divisions

Significance of Microcytosis

Fe deficiency due to chronic blood loss

Correlates with ↓MCV

Breed variation: Akita, shiba

Age variation: foals <6months

Morphology of Microcytosis

Polychromatophilic Erythrocyte

Formation: accelerated erythropoiesis

Significance of Polychromatophilic Erythrocyte

Regenerative anemia

Purple color is caused by RNA

Immature stage before normocyte is released from bone marrow

Morphology of Polychromatophilic Erythrocyte

Ways to detect Polychromatophilic Erythrocyte

Polychromatophils on Diff Quik Stain

Reticulocytes via new methylene blue stain

Hypochromic Erythrocyte

Formation: incomplete Hgb synthesis

Increased central pallor

Significance of Hypochromic Erythrocyte

Regenerative anemia

↓MCHC (Mean cell hemoglobin concentration)

Morphology of Hypochromic Erythrocyte

Hypochromic Erythrocyte Pt. II

Formation: defective Hgb synthesis due to lack of Fe

Significance of Hypochromic Erythrocyte pt. II

Chronic blood loss leading to Fe def

↓MCHC

Morphology of hypochromic Erythrocyte Pt. II

4-year-old female mixed breed dog is presented with pale mucous membranes. Blood smear had uneven distribution of erythrocytes with low density erythrocytes, moderate anisocytosis and many microcytosis. What is the most probable cause of these findings?

C. Fe-deficiency

What term best describes abnormal shapes of erythrocytes?

E. Poikilocytosis

Echinocyte(echino- = spiny)

Formation: alkaline pH of glass leads to membrane changes

Significance of Echinocyte

Slow drying artifact= crenated RBCs

Hyponatremic dehydration

Rattlesnake venom

Morphology of Echinocytes

Spherocyte(sphero=round)

removal of membrane or defective membrane

Significance of Spherocytes

Immune-mediated hemolysis

Macrophages in the spleen remove membrane coated with antibodies causing cell to change from discocytes to spheroid shape

Seen only in Dogs

Morphology of Spherocytes

Codocytes: young eryrthrocytes

Codocytes: hypochromasia

Codocytes: liver disease

Schizocyte formulation

intravascular RBC trauma

Schizocytosis seen in:

Microangiopathy

Intravascular coagulation (fibrin strands)

Vasculitis

Morphology of Schizocytes

Keratocyte formulation

intravascular RBC trauma

Significance of Keratocyte

Microangiopathy

Intravascular coagulation (fibrin strands)

Vasculitis

Morphology of Keratocyte

Eccentrocyte formulation

oxidative damage to RBC membrane

Eccentrocytosis significance

overwhelming exposure to oxidants

Morphology of Eccentrocyte

Pyknocyte formulation

oxidative damage to membrane and hgb

Significance of Pyknocytes

overwhelming exposure to oxidants

(similar to Heinz body anemias)

hereditary defects in RBC enzymes

Morphology of Pyknocytes

Inclusion bodies: Heinz Bodies formulation

oxidative damage to Hgb

Oxidants overwhelm reductive capacity

In anaerobic glycolysis (Fe2+ --- Fe3+ causing precipitation of Fe on membrane)

Significance of Heinz bodies

Heinz body anemias

Examples: acetaminophen, onions, red maple leaves, zinc toxicosis

Cats different – common due to their HgB structure

Morphology of Heinz bodies

7-year-old dog with pale mucous membranes is presented. Blood film has uneven distribution, low density erythrocytes, moderate anisocytosis, macrocytosis, and occasional Heinz bodies. What pathologic process is most likely?

D. Oxidative damage to hemoglobin