Buffy Coat Component of Blood Flashcards
Components of buffy coat
- Makes up less than 1% of blood
- Contains leukocytes (WBCs) and platelets
Leukocytes
- Granulocytes (neutrophils, eosinophils, basophils)
- Agranulocytes (lymphocytes, monocytes)
CBC part of buffy coat
- Total WBC count
- Corrected WBC
- Differentials
- Granulocytes
- Agranulocytes - Other
- Looks at morphological abnormalities
- Unidentifiable/identifiable cells that are not normally there - Platelets
WBCs vs. corrected WBCs
- WBCs have a nucleus whereas RBCs do not
- Corrected WBCs is the count of WBCs when removing the defected nucleated RBCs
How do neutrophils appear on a CBC?
- Appear as either segs (segmented/more mature) or bands (more immature)
Granulopoiesis - Production of granulocytes from the bone marrow
- Includes making neutrophils, eosinophils, basophils
Steps of granulopoiesis
- Common myeloid progenitor
- GM progenitor
- Myeloblast
- Promyelocyte- makes lysosomal hydrolases called azurophilic granules which are in all three types of granulocytes
- Myelocyte- make molecules specific for the each granulocyte type (neutrophils, eosinophils, basophils)
- Metamyelocyte- finished production. Lysosomal hydrolases and molecules specific for the granulocytes
- Band nucleus of granulocytes
- Segmented nucleus of granulocytes
Neutrophils
- Most common WBC type in circulation of dogs and cats
- Good at phagocytosis of bacteria
- Very rapid response to inflammation/infection
- Left shift indicated inflammation
–> Bone marrow will want to produce more RBCs so there will be a higher level of immature neutrophils in the blood - Granules don’t pick up much stain
- Lifespan 1-4 days
What does a left shift indicate/mean?
- Indicates inflammation
- There will be more immature band cell neutrophils
Eosinophils
~2%
- Secretory granules. Important for invaders that are too big to phagocytose. Granules are released outside and attack pathogens.
- Specialized for worms/parasitic infection
- Play a role in Allergic reaction and moderate local inflammation
- Life span = 1-2 weeks
Basophils
- Rarest, less than 1%
- Protect against ticks and round worms
- Play a role in allergic reaction and some inflammatory response
- 1-3 days life span
Monopoiesis
Production of agranulocytes from the bone marrow
- No distinguishable features during development
- Will leave bone marrow after a few hours. There is no storage pool.
Steps of monopoiesis
- Common myeloid progenitor
- GM progenitor
- Monoblast
- Promonocyte
- Monocyte
- Macrophage
Monocytes
~5-10%
Enter tissue and then mature into macrophages
- Macrophage precursor
Can have any shaped nucleus but not segmented
Hours to years lifespan
Macrophages
Play a critical role in initiation, maintenance, and resolution of inflammation
Lymphopoiesis
Production of lymphocytes
Lymphocyte life span outside blood
Hours to years
Steps of lymphopoiesis
- Common lymphoid progenitor
- T-lymphoblast OR B-lymphoblast
- T-cells OR B-cells
- T-cells become NK cells OR B-cells become Plasma cells
B-cells
Differentiation to mature B-cells occur in peripheral lymphoid tissues
T-cells
Development in thymus, lymph nodes, and spleen
What immune system are T and B-cells involved in?
Adaptive Immunity!
- T-cell involved in cell-mediated immunity
- B-cell involved in humoral immunity
What WBCs are the main defense in innate immunity?
- Neutrophils
- Tissue macrophages
What WBCs are the main defense for adaptive immunity?
lymphocytes
Lymphocytes
- Most common agranulocytes
- Spherical nuclei
- Smallest leukocytes
- Very little cytoplasm
Platelets
- Small minute discs, no nuclei
- Have contractile proteins (actin and myosin) to help seal off wounds
- ER and golgi apparatus present to make enzymes and store calcium ions
- Mitochondria to make ATP
- Surface also contains glycoproteins that will stick to injury sight and can trigger wound healing
- Half life ~8-12 days then eliminated by macrophage tissue system (mostly spleen)
- Produced when parts of megakaryocytes get cleaved off and released into the circulation
Types of macrophages
- Tissue macrophages
- Inflammatory macrophages
Tissue macrophages
Macrophages that reside in the tissues
- CNS (microglia)
- Connective tissue (histiocytes)
- Liver (alveolar macrophages)
- Lung
- Lymph nodes
- Spleen
- Bone marrow
- Serous fluid
- Skin
Inflammatory macrophages
- Arise from monocytes, and are attracted to areas of inflammation via chemotaxis
- Characterized by specific markers
Functions of macrophages
Contain more than 100 different substances that can deactivate and denature cellular components engulfed by phagocytosis. Will destroy:
- Damaged RBCs (mainly destroyed in spleen)
- Foreign particles
- Intracellular parasitic bacteria, protozoa, fungi, and worms
Defence against tumours
Function with lymphocytes to activate immune system by presenting antigens and regulate inflammatory response
Can intracellular parasitic organisms continue replication after phagocytosis by macrophages?
No
How does the macrophage phagocytose invaders?
- Takes up antigen by phagocytosis
- Breaks down the antigen into fragments in the lysosome
- A class II MCH protein binds an antigen fragment
- MHC protein presents the antigen to a T cell
Normal species differences in WBCs
- Total number of WBCs varies, but overlaps among species
- Neutrophils and lymphocytes are the most abundant for all species
