B Y: J E N N I F E R B U I , K AT H Y L U U , D A N I E L M I R A N D A , T I N A Y I P
PHM142 Fall 2014
Instructor: Dr. Jeffrey Henderson

Immune System
Innate Immune System
First line of defense against pathogens
Adaptive Immune System
Protects from reinfection

Innate Immune System
 Physical Barriers
 Inflammation
 Complement System
 Immune Cells
 Neutrophils, eosinophils, basophils, macrophages, dendritic cells

Eosinophils
Leukocytes
Basophils
Neutrophils

Cells Involved in Innate Immunity
 Characteristics of Eosinophils
 Stains Red
 Receptors for IgE antibody
 Responds to mainly parasitic infections
 Granulocyte and Polymorphonuclear Leukocyte (PMN)

Cells Involved in Innate Immunity
 Characteristics of Basophils
 Stains Purple/Blue
 Cytoplasm filled with granules
 Least Common
 Contains Heparin
 Contains Histamine
 Granulocyte and PMN

Cells Involved in Innate Immunity
 Characteristics of Neutrophils
 Most common leukocyte and has high motility
 Attracted to site of infection by chemotaxins

Cells Involved in Innate Immunity
 Characteristics of Neutrophils
 Performs phagocytosis
 Destroys internalized microorganism with proteins from granules

Macrophages
 Phagocytic cell – Ingest and destroy microorganisms

Pattern Recognition Receptors (PRRs)
 Used to differentiate self from non-self
 Detect PAMPs

Macrophages

Dendritic Cells
 Long-finger like projections
 When immature – act as phagocytic cell

Dendritic Cells

B-cells
 Many surface proteins
 Very diverse -> nearly 1 billion different B-cells
CD268
(BAFF-R)
CD40
CD20
CD22
CD24
CD57
CD45R/B220
CD5
CD86
CD79a

 Y-shaped protein
 Recognize antigens
 Variable region
 Assembled via VDJ recombination
Antibody
Variable
Region
Fixed
Region

B-cell receptor (BCR)
 Distinguishes B-cells from other immune cells
 Allows B-cells to: recognize antigens & general signal
Ligand binding
Signal transduction

Adaptive response
1. B-cell binds antigen
2. Antigen taken up and digested
3. Peptides presented on MHC II
4. Attracts T-cells

B-cell differentiation
Memory cell
 Retain bound receptor for future
Plasma cell
 Produce antibodies

T Cell Receptors (TCR)
 The antigen must be:
1. degraded to short peptide sequences
2. presented by APCs on MHC molecules

CD4 (Helper) T Cells
 Activate macrophages
 Enhance inflammation
 Stimulate B cells to produce antibodies

CD8 (Killer) T Cells
 Secrete cytotoxins and cytokines to kill infected cells

Cross-presentation
 Extracellular material from infected cell is phagocytosed by APC to be presented on MHC class I

References
 Mauri, C, Bosma, A (2012). "Immune Regulatory Function of B Cells". Annual Review of
Immunology 30, 221–41.
 Murphy, K., & Travers, P. (2012). Janeway's immunobiology (8th ed., p. 5-7, 11, 77, 78, 347,
348). New York: Garland Science.
 Owen, J., Punt, J., & Stranford, S. (2013). Kuby immunology (7.th ed., pp. 147-149). New York:
W.H. Freeman.
 Parham, P. (2009). The Immune System (3rd ed., pp. 73, 79-81, 126, 133-134, 144-145, 227-
228). New York: Garland Science.
 Silverthorn, D. U. (2012). Human Physiology: An Integrated Approach. (6 th ed., pp. 131-134).
New York: Pearson.
 Young, B., Lowe, J. S., Stevens, A., & Heath, J. W. (2006). Wheater's Functional Histology. (5 th ed., pp. 20-23) Newcastle: Elsevier Limited.

Cell Type
Eosinophils
Basophils
Summary slide
Physical Characteristics
Visible granules, multi-lobed nucleus, granules stain red with eosin
Functional Characterisitics
Primarily contain receptors for the IgE antibody, mainly fight against parasitic pathogens
Visible granules, multi-lobed nucleus, granules dominate cytoplasm
Contains histamine for increased capillary permeability to
WBC’s, and heparin for anticoagulant properties.
Neutrophils Visible granules, multi-lobed nucleus
Macrophages Contain pattern recognition receptors on its surface to identify pathogens, example is mannose receptor
Dendritic Cells Long finger like projections, TLR, ICAM-
1 and ICAM-2
Phagocytic functions, internalizes and destroys invading microorganisms
Primary role is phagocytosis, it engulfs the cell and breaks it down using lysosomal hydrolase
Immature dendritic cells are phagocytic, when they undergo maturation, they become antigen presenting cells (APCs) and now have the ability to present antigens to naïve T-cells
B cells Spherical, many surface proteins
Helper T Cells TCR, CD4 coreceptors,
Killer T Cells TCR, CD8 coreceptors
Differentiate into memory cells (retain membrane bound receptors) and plasma cells (produce antibodies)
Secretes cytokines to enhance action of other immune cells: 1)
Activate macrophages 2) Enhance inflammation 3) Activate B cell to produce antibodies
Kills infected cells by secreting cytotoxins and cytokines to