PHM142 Fall 2015
Instructor: Dr. Jeffrey Henderson
Immunology:
Categorization of
Leukocytes Action
SIAMAK BADIE, SALIMAH CHAMPSI, FANYA GAO, DANIELLE PORTER
Leukocytes
5 Classes:
Neutrophils (40% - 75%)
Eosinophils (1% - 6%)
Granulocytes
Basophils (less than 1%)
Monocytes (2% - 10%)
Lymphocytes (20% - 45%)
Agranulocytes
Neutrophils – Mechanism of Action
Characteristics:
- Innate immune response
- Most abundant
- First responders
- Granulocytes
Damaged
Cells
Cytokines
Phagocytosis
Degranulation
 Oxidative burst: use
energy from NADPH to
form oxygen free radicals
 Release anti-microbial
compounds
NETs
 Trap microbes
Basophils – Mechanism of Action
Allergic Response
Degranulation
B-phil
Th
cell
B cell
Produce antibodies
Eosinophils – Mechanism of Action
Cell Activation
Degranulation
Degranulation
E-phil
Host Defense
(Peroxidase + Rnase)
Monocytes – Mechanism of Action
Hematopoietic Stem
Cells
LP
MP
Bone Marrow
Blood
Tissue
Ly6C Monocyte
Macrophage
- Phagocytosis
MDP
CDP
Ly6C+
Monocyte
MonocyteDerived DC
- Process and
present antigen
to T cell
Pre-CDC
PDC
Classical DC
PDC
- Process and
present antigen
to T cell
- Respond to viral infection
- Act as APC and control T
cell responses
Lymphocytes– Mechanism of Action
Adaptive Immune Response
Antigen
Innate Immunity: NK Cells
-Non specific attack on
tumours and infected cells
-Release cytotoxic granules
to induce cell apoptosis
Macrophage
MHC
Helper T cell
Cellular: Cell-Mediated
Humoural: Antibody-Mediated
B cell
T&B
Memory
T cell
Suppressor T
Cells
Antibodies:
Signal destruction
pathways
Granules: breakdown
cell membrane of
pathogens
Summary
Neutrophils:
 Phagocytosis: use energy from NADPH to form oxygen free radicals
 Degranulation: secrete antimicrobial compounds
 Formation of neutrophil extracellular traps: trap microbes
Eosinophils:
 Work mainly to counter infections
 Granules produce ROS/RNS and ribonucleases
Basophils:
 Work mainly in allergic responses
 Granules contain histamine, heparin, and antiparasitic molecules
Monocytes:
 Circulate in blood and differentiate into macrophages and dendritic cells in tissues during inflammation
 Digest pathogens and stimulate antibodies
Lymphocytes:
 Adaptive immunity: antibody mediated B cells and cell mediated T cells attack antigen and provide antigen memory
 Innate Immunity: natural killer cells attack non-specifically through release of cytotoxic granules
References
1. Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland
Science; 2002. Helper T Cells and Lymphocyte Activation. Available from:
http://www.ncbi.nlm.nih.gov/books/NBK26827/
2. Amulic B, Cazalet C, Hayes GL, Metzler KD, Zychlinsky A. Neutrophil function: from mechanisms to
disease. Annu. Rev. Immunol. 2012; 30: 459-489
3. Bandeiro-Mela, C., & Weller, P. Mechanisms of eosinophil cytokine release. PMC. 2005; 100(1), 73-81
4. Falcone, F., Hass, H., & Gibbs, B. The human basophil: A new appreciation of its role in immune
responses. Blood Journal. 2000; 96(13): 4028-4038
5. Geissmann F, Manz MG, Jung S, Sieweke MH, Merad M, Ley K. Development of monocytes,
macrophages and dendritic cells. Science. 2010;327(5966):656-661
6. Maddaly, R., Govind, P., Balaji, S. et al. Receptors and signalling mechanisms for B-lymphocyte
activation, proliferation and differentiation- Insights from both in vivo and vitro approaches. FEBS
Letter. 2010; 584(24): 4883-4894