Download L18: Immune System, Part 1

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The Immune System
Immune System
Lecture 18, Part 1
Winter 2014
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Innate Immunity-Mammals
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Cast of characters
• Where can pathogens enter the body?
• What are the barriers to pathogen entry?
Lymphatic System
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Inflammatory (histamine) response
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Toll-like Receptors (TLR)
Fig. 43.7
Fig. 43.8
Fig. 43.8
Fig. 43.6
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Inflammatory (histamine) response
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Intracellular vs extracellular pathogens
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• How recognize?
• Neutrophils
– Major histocompatibility
complex
– MHC class I – intracellular
– MHC class II- extracellular
Fig. 43.8
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Extracellular
pathogens
• Who recognizes?
– B cells?
• What are B cells recognizing?
B cells
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• ~ 1 million different B cells in body
• Y shaped receptor
• Binds to antigens
– Antigens
– Epitope (antigenic determinant)
Fig. 43.9
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B cells
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• Antigen receptor
– ~100,000 identical receptors/cell
– Individual cells have specificity
• How does this
happen?
• Antibody or immunoglobin (Ig)
– Protein secreted by plasma cells (differentiated B cells) that bind
to a particular antigen
Fig. 43.10
Fig. 43.18
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B Cell Activation
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B Cell Activation
• Clonal selection in B
cell
• Effector cells
– Short lived
– Attack antigen /
pathogen
• Memory cells
– Long-lived
Fig. 43.18
Fig. 43.18
Clonal selection of B Cells
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• What is missing from this diagram?
Humoral
Response
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Opsonization
• Also help form aggregates
Neutralization
Fig. 43.14
Fig. 43.21
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Humoral Response
• Antibodies work with proteins of complement
system
Fig. 43.21
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