Download Chapter 17b - Foothill Technology High School

Blood, part 2
Leukocytes, Immune System Basics,
and Leukocyte Disorders
Leukocytes (WBCs)
• Only complete cells
• < 1% total blood volume
• Diapedesis: ability to leave blood vessels to
move independently through tissues
– Ex. loose CT or lymphoid tissues
– Use amoeboid motion, following chemical trail
released by damaged cells
• Infections can increase WBC count to over
11,000 / mm3
– Normal WBC count ranges from 4800 – 10,800
Leukocyte Quantities
(Most to least)
Never
Let
Monkeys
Eat
Bananas
Granulocytes
• Include:
– Neutrophils, Eosinophils and Basophils
• Have membrane-bound granules: vesicles
w/digestive enzymes and antimicrobial proteins
• Granules can be visualized using Wright stain
• Lobed nuclei
• Larger than RBC; shorter-lived
• Phagocytic
Neutrophils
• Most common WBC
• Stain:
– Granules stain w/ acidic (red) and basic (purple/black)
Wright stain dyes
– lilac colored cytoplasm
• 2 Types of granules that lyse bacteria:
– Lysosomes
– Antimicrobial proteins: defensins
• 3-6 lobes in nuclei
• Kills Bacteria and Fungus
• Slays bacteria w/aid of “respiratory burst”
– O2 metabolized to create H2O2 and bleach
Eosinophils
• 2 – 4 % of WBCs
• Red granules (acidic dye)
– w/ lysosome-like digestive enzymes
• Bi-lobed Nuclei
• Kills mostly parasitic worms
• Lessens allergies by phagocytizing immune
complexes
• Same size as Neutrophil
Basophil
• Rarest WBC (.5 – 1%)
• Have U- or S- shaped nuclei
• Purple/Black Granules (basic dye)
– w/histamine that
•
•
•
Function like mast cells in CT
Dilate vessels, increase inflammatory response
Attracts other WBCs
– w/heparin that
•
•
•
Promotes inflammation
Increases heparin
Acts as anticoagulant
• Same size as neutrophil
Agranulocytes
• Include:
– lymphocytes (T- and B- ) and monocytes:
• Lack visible cytoplasmic granules
– Have spherical or kidney-shaped nuclei
• Major players in specific immune response.
–
–
–
–
Recognize invaders
Produce antibodies
Attack viruses and tumors
Act as phagocytic macrophages
Lymphocytes
• 25% of WBC
• Large, dark-purple, circular nuclei with thin rim of blue
cytoplasm
• Found mostly in lymph nodes (some circulate in blood)
• Two types :
– T cells:
• Helper T: coordinates immune response
• Killer T: directly kills invaders, tumors, viruses
– B cells: recognize invaders, make antibodies that
bind, trap, and mark intruders for destruction
Monocytes
•
•
•
•
•
3-8 % of WBC
Largest leukocytes
Abundant pale-blue cytoplasm
Purple-staining, U- or kidney-shaped nuclei
Leave vessels, enter tissue, and become
macrophages where they
– actively phagocytize invaders marked by antibodies
• Help activate lymphocytes by “presenting” the
antigen of invaders they digest
Summary of Leukocyte Histology
Practice Identification
Granulocyte
Eosinophil
Granulocyte
Neutrophil
Granulocyte
Neutrophil
Agranulocyte
Lymphocyte
Granulocyte
Basophil
Agranulocyte
Monocyte
More Practice
Neutrophil
Eosinophil
Lymphocyte
Basophil
Monocyte
Leukopoiesis (WBC Differentiation)
Stem cells
• Stem Cell Origin:
Hematocytoblast
• Myeloid Stem Cells:
−
−
originate all WBCs
except Lymphocytes
• Myeloblasts and
Lymphoblasts:
−
−
“committed”
lysosome formation begins
Hemocytoblast
Myeloid stem cell
Committed
cells
Developmental
pathway
Myeloblast
Myeloblast
Promyelocyte
Promyelocyte
Eosinophilic
myelocyte
Basophilic
myelocyte
Neutrophilic
myelocyte
Eosinophilic
band cells
Basophilic
band cells
Neutrophilic
band cells
Basophils
Neutrophils
(c)
Lymphoid stem cell
Myeloblast
Promyelocyte
Promonocyte
• Differentiation continues:
−
−
granule accumulation
lobing of nuclei
Eosinophils
(a)
(b)
Lymphoblast
Prolymphocyte
Monocytes
Lymphocytes
Some
(e)
become
(d)
Plasma cells
Agranular leukocytes
Granular leukocytes
Some become
Macrophages (tissues)
What stimulates Leukopoiesis?
• Interleukins (IL) and colonystimulating factors (CSFs)
– act as chemical stimuli
– Type and amount
determines the type of
leukocyte formed
• Macrophages and T cells
are most important sources
of ILs and CSFs
– released when a
pathogen (disease
causing organism) is
detected
Fun Fact:
IL and CSFs
often used to
stimulate
marrow of
cancer
patients
Leukocyte Disorders:
Leukemia
• cancerous conditions of a “line” of WBCs
• Acute leukemia:
– blast-type cells
– usually in children
– progresses quickly
• Chronic leukemia:
– later stages of cyte-type cells
– usually adults
– progresses slowly
• Named after cell type involved. Ex…
– Myelocytic, Lymphocytic, Lymphoblastic leukemia
Leukocyte Disorders:
Leukemia
• Bone marrow crowded out with cancerous, immatur
leukocytes (no immune protection)
Anemia
Bleeding (Internal)
Infections
Fever, weight loss, pain
Fatal
Leukocyte Disorders:
Leukopenia
• Opposite of Leukemia
• Abnormally LOW WBC count
– Usually drug induced
• ex. chemo• Glucocorticoids (steroids that suppress IS)
– HIV infection