Overview of the Course

Lecture 1 The Components of the Immune SystemLecture 2 Innate ImmunityLecture 3 Antigen Recognition by T lymphocytesLecture 4 Antigen Presentation by T lymphocytesLecture 5 Antigen Recognition by B cell ReceptorsLecture 6 The Humoral Immune ResponseLecture 7 Signaling Through Lymphocyte ReceptorsLecture 8 The Development and Survival of LymphocytesLecture 9 T-cell Mediated ImmunityLecture 10 Adaptive Immunity to InfectionLecture 11 Mucosal ImmunityLecture 12 HIV InfectionLecture 13 Failures in Host Defense MechanismsLecture 14 Evasion of the Immune System by Pathogens

Lecture 1: The Components of the Immune System

Summary of the Entire Immunology Unit

Kill the pathogen anddon’t harm the host

Questions to Consider

Why do you only get some infections like chicken pox aka varicella zoster only once?

How do you generate an system able to recognize a broad array of pathogens with a high level of sensitivity and specificity using a finite amount of coding DNA?

Why do subsequent immune responses to a pathogen occur more rapidly and at higher titers than previous immune responses?

How does the immune system provide a high degree of sensitivity and specificity to the broad array of pathogens without attacking self?

Why are T cells and B cells effective against different pathogens and how do T cells and B cells see antigens differently?

David

Smallpox Infection

Immunity

From the Latin word “immunitas” meaning exemption from civic duties.

Historically immunity was the observed protection from infection by individuals previously exposed or infected.

Chinese made children inhale powder from crusted smallpox lesions.

Eradication of Smallpox by Vaccination

Functional Immunity

Innate Acquired

Barrier Skin Mucosal immunity

Soluble Protein Complement Antibodies

Cells Phagocytes T and B cells

Mediators IL-1, TNF -interferon

Function of Immune System

Identification- foreign vs. self

Designation- accentuate foreign origin

Recruitment- mobilize effectors

Elimination- clear pathogen

Prevent Recurrence- prepare for future

Sensitivity and Specificity of Detection Determines

the Effectiveness of Immune Surveillance

Design of the Immune System

Specificity- fine distinctions

Diversity- broad repertoire

Memory- accelerate next response

Demobilization- after clearance

Distinguish self from non-self- prevent attack of normal tissues

Mobilization of the Immune System

Cognitive phase- binding of antigen to specific cell that recognizes it

Activation phase- proliferation and differentiation of antigen-specific cell

Effector phase- assemble response to eliminate infection

Targets of the Immune System

CD Nomenclature

CD = Cluster of Differentiation

Cells express unique membrane proteins identified by monoclonal antibodies.

Cells are identified by the pattern of cell- specific CD markers expressed.

CD proteins are identified by sequential numbers.

Hematopoietic Lineage

Histological Appearance of Lymphocytes

Activation of Lymphocytes

How Does the Immune System Provide a High Degree of Sensitivity and Specificity to the Broad Array of Pathogens Without Attacking Self?

Clonal Selection Hypothesis

Expression of Antigen-specific Membrane Proteins

Clonal Selection

The Antibody Recognizes an Epitope Within the Antigen

Development of a Secondary Amplified Response

Clonal Expansion

Structure of Antigen Recognition Molecule

Different Antigen Recognition Molecules Are Used by B Cells and T Cells

Identity of Lymphocytes in the Peripheral Blood

Primary and Secondary Lymphoid Tissues

Lymph Node Organization

Spleen Organization

Anatomical Localization of B cells and T Cells

B Cells and T cells Recognize Different Antigenic Contexts

B Cells use the Immunoglobulin Molecule to recognize 3D structures of the native molecules.

T Cells use the T cell receptor to recognize primary structures.

Structure of Immunoglobulin Molecule

Function of Immunoglobulin Molecules

T cells Recognize Peptides Presented by Cells

Function of Cytotoxic and Helper T Cells

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Questions to Consider

Why do you only get some infections like chicken pox aka varicella zoster only once?

How do you generate an system able to recognize a broad array of pathogens with a high level of sensitivity and specificity using a finite amount of coding DNA?

Why do subsequent immune responses to a pathogen occur more rapidly and at higher titers than previous immune responses?

How does the immune system provide a high degree of sensitivity and specificity to the broad array of pathogens without attacking self?

Why are T cells and B cells effective against different pathogens and how do T cells and B cells see antigens differently?