Gábor Koncz

Lectures 1-9, 25-26,29-30

Book, Abul K. Abbas: Basic Immunology

In this lecture:

1. General warm up, why do we need immune system

2. Simple schema of the immune system

3. 3 lexical data

Do we need immune system?

Bacteria

Viruses

parasites

Virus

3 hrs

3 hrs

DiversityFast development

PATOGENS

GENERATION TIME OF PATHOGENS

In the active phase of the HIV 10billion viruses develop/day

Bacteria may divide in every 20 minutes

The human microbiome

We live in a potentially hostile world filled with infectious agents of diverse size, shape, and composition which would very happily use us as „petri

dishes”…

HIV Flu S. aureus

Streptococus. Salmonella Mycobacterium tuberculosis

Lysteria Pneumocystis carnii

Andida albicans Trypanosoma brucei

Schistosoma mansoni

How can we survive????

1. The interest of microbes

The human microbiome

Normal bacterial flora can be differnt in each person

Tightly regulated balance between commensal flora and the immunen system

Transplantation of bacteria?

2. The immune system

THE TWO ARMS OF THE IMMUNE SYSTEMDifferentiation between harmless and harmful impactsDETECTION OF STRESS AND DANGER SIGNALSINNATE IMMUNITY

Differentiation between self and non-self structuresAntigen-specific recognitionADAPTIVE IMMUNITY

INNATE IMMUNITY- immediate reaction- not antigen-specific- no memory

ADAPTIVE IMMUNITY- developes in several days- specific- has memory

Neutralization and elimination of foreign and harmful structuresCOORDINATED AND REGULATED ACTIONS

Both the innate and adaptive arms of immunity are required for elimination of pathogens

THE TWO ARMS OF THE IMMUNE SYSTEM

Monocytes, Macrophages, Dendritic cells, Granulocytes, NK

cells and Complement componentsB and T cells

Monocytes, Macrophages, Dendritic cells, Granulocytes, NK

cells and Complement components

Immune system

Innate immunity Adaptive Immunity T cells B cells

Intracellularpathogens

Extracellularpathogens

The simplest Schema of the immune system

The main functions of the immune system:

Recognition

Communication

Elimination (effector functions)

Innate immunity Adaptive Immunity T cells B cells

Intracellularpathogens

Extracellularpathogens

Recognition

Communication

Elimination

The simplest Schema of the immune system

THE ANTIGENDefinition and properties

Antigenic determinant (epitope)

Antigen recognition by B and T cells

Any chemical structureSoluble or corpuscleSimple or complex

Originated from the body or comes from outsideGenetically self or non-self

Natural or artificial

• ANTIGEN (Ag) - any substance, which is specifically recognized by the mature immune system of a given organism

DEFINITIONS

• ANTIGENICITY– capability of an antigen to bind specifically with certain product of the adaptive immunity: TCR or BCR/antibody,

– immunogenicity - capability of an antigen to induce an (adaptive) immune response,

– tolerogenicity - capability to induce immunological tolerance, specific immune non-responsiveness

DEFINITIONS

FACTORS INFLUENCING IMMUNOGENICITY I.

From the aspect of our body:

• Genetics (self/non-self)– species (evolutionarily nonconserved molecules)– individual differences (e.g. MHC polymorphism – see later)

• Age – newborn – less reactive immune system– elderly – no new lymphocytes

• Physiological condition (pl. immunodeficiencies, starvation)

FACTORS INFLUENCING IMMUNOGENICITY II.

From the aspect of the antigen:

• Physical-chemical properties of the Ag

– size/complexity (bigger more epitopes, role of carrier)– corpuscular (cell, colloid) or soluble– denatured or native (different epitopes!)– degradability (by APCs)

• Availability (crystalline proteins of the eye are not presented to lymphocytes)

FACTORS INFLUENCING IMMUNOGENICITY III.

From the aspect of vaccination:

• Dose• Route

– intradermal/subcutan > intravenous > oral > intranasal (oral vaccine against polio virus!)

Part of the antigen which directly interacts with the antigen-binding site of a defined immunoglobulin (BCR / antibody) or TCR

ANTIGENIC DETERMINANT (=EPITOPE)

B cell epitope T cell epitope

recognized by B cells

• proteins polysaccharides lipids DNA steroids etc. (many artificial molecules)

• cell or matrix associated or soluble

recognized by T cells

• proteins mainly (8-23 amino acids)

• requires processing by APC