Blood
Part II
Leukocytes
Bio 202
Mark Muchna
Blood: Leukocytes
Blood = plasma + formed elements (RBCs, WBCs, platelets)
Leukocytes = white blood cells = WBCs
· quantity
· function – defense
emigration (diapedesis)
Two major groups:
1. Granulocytes
2. Agranulocytes
Leukocytes: Granulocytes
1. Granulocytes
· Cytoplasm - obvious granules (vesicles - secretory and lysosomes)
· Nucleus – lobes
· Three types: neutrophils, eosinophils, basophils
neutrophil
eosinophil
basophil
Leukocytes: Granulocyte - Neutrophil
A. Neutrophil
· most common WBC; 50 – 70%
· nucleus: 2 – 5 lobes (older → ↑# lobes)
– often called PMNs or polys
· cytoplasm: fine granules
· staining – “neutral-loving” – pale lilac color
- does not strongly attract acidic (red) dyes or basic (blue) dyes
Leukocytes: Granulocyte - Neutrophil
Neutrophil Function:
· phagocytes - very mobile, active - esp. bacteria / some fungi
- often first WBC at injury
- neutrophil with its granules has chemicals to kill ingested
pathogens
- chemicals neutrophil can produce ex. strong oxidants
(OCl¯,H₂O₂), lysozymal enzymes , defensins
Leukocytes: Granulocyte - Neutrophil
· short life span in circulation
· engulfs 1 – 2 dozen bacteria - live 30 minutes or less
· dies → releases chemicals attract more neutrophils
accumulation of dead neutrophils/cell debris = pus
Leukocytes: Granulocyte - Eosinophil
B. Eosinophils
· 1 – 4%
· nucleus – bilobed
cytoplasm - granules - stain red with acid dye (eosin)
Function:
- phagocytes
- fight parasitic worms →degranulate - release digestive enzymes
- involved in allergies / asthma
Leukocytes: Granulocyte - Basophil
C. Basophil
· 0.5 – 1%
· nucleus – U or S shape
cytoplasm – granules stain purple with basic dye
Function:
- granules contain histamine (vasodilation); heparin
- inflammatory response
- similar to mast cells in CT
Leukocytes: Agranulocytes
2. Agranulocytes
· Cytoplasm - smaller vesicles and lysosomes
· Nucleus - round / kidney shaped
· Two types : monocytes and lymphocytes
monocytes
lymphocytes
Leukocytes: Agranulocytes - Monocytes
A. Monocyte
· 3 – 8%
· largest WBC
· nucleus – kidney shaped
cytoplasm – pale blue – vacuoles
Function - phagocyte
- leave circulation → macrophages
Leukocytes: Agranulocytes - Monocytes
Macrophages
· mobile, active phagocytes
· ingest pathogens/tissue debris
· important in the immune response
Leukocytes: Agranulocytes - Lymphocytes
B. Lymphocytes
· 25 – 40%
· nucleus – large, round
cytoplasm – light blue
· most in lymphoid tissues
· immunity
Differential
Important diagnostic blood test
Neut: 50 – 70
Bands: 2 - 6
Lymph: 25 – 40
Mono: 3 – 8
Eo: 1 – 4
Baso: 0.5 - 1
Hematopoiesis
Leukopoiesis (1)
Hemocytoblast
↓
Myeloid stem
↓
Progenitor cell
↓
↓
↓
↓
band
↓
↓
Monocyte
Neutrophil,
Eosinophil,
Basophil
Hematopoiesis
Leukopoiesis (2)
Hemocytoblast
↓
Lymphoid stem
↓
↓
B Lymphocytes
T Lymphocytes
Natural Killer Cells
Leukocytes
Leukopoiesis
- still learning!
- chemical messengers involved: ex. colony stimulating factors
Life span
- most live a few days; if fighting infection – hours/minutes
- monocytes can live for months
- lymphocytes can live hours– years
Terms to Know:
Leukocytosis
Leukopenia
Leukemia
CBC
CBC - very common, routine diagnostic blood test
Some of the tests on CBC:
1. WBC count: 5,000 – 10,000 / mm³ = µl
2. WBC differential
3. Hematocrit (PCV): Men 42 – 52% Women 36 – 48%
4. RBC count: Men 4.5-5.5 X 10⁶/µl; Women 4.0 – 5.0 x 10⁶/µl
5. Hemoglobin Men: 14 – 17.4 g/dl Women 12 – 16 g/dl
6. Platelet count 140,000 – 400,000 / mmᶟ
Source: WebMD
CBC
Example
Histology: H&E stain
· most cells colorless/transparent
· histological sections, need a stain
· often uses dye(s)
Hemotoxylin and Eosin (H&E) staining
· most widely used in medicine
Two dyes:
1) Eosin - acid dye - stains basic components of cell red/pink
(ex. proteins in cytoplasm)
2) Hematoxilyn - “basic dye” - stains acid components purple/blue
(ex. nucleic acids – DNA nucleus/RNA ribosomes)