invaders of the body
TRANSCRIPT
ANTIGENS: TRIGGERS OF ANTIGENS: TRIGGERS OF AQUIRED IMMUNITYAQUIRED IMMUNITY
PATHOGEN. PATHOGEN. Organism that cause a disease.Organism that cause a disease.
VIRULENCE. VIRULENCE. Ability to cause disease.Ability to cause disease.
PATHOGEN. PATHOGEN. Organism that cause a diseaseOrganism that cause a disease
PRIMARY PATHOGEN. PRIMARY PATHOGEN. Organism that cause a disease almost every timeOrganism that cause a disease almost every time it invades a healthy individual.it invades a healthy individual.
SECONDARY PATHOGEN. SECONDARY PATHOGEN. Organism that cause a disease only if theOrganism that cause a disease only if the immune response is impaired.immune response is impaired.
Pinchuk: Schaum’s Outline of Theory & Problems of Immunology. The McGraw−Hill Companies, 2004
IV_10_1_The_immune_Response.swf
ANTIGEN(Antibody generator)
Antigen (Ag)
Ab
ANTIBODY (Ab = Antigen binding)
• Antibodies do not bind to the whole agent
• Binds to one of many molecules (Ag)
• Many for one organism
• Binds to a restricted part of the Ag (Epitope)
• Ag has many epitopes (different or repeated)
ANTIBODY (Ab = Antigen binding)
• Antibodies do not bind to the whole agent
• Binds to one of many molecules (Ag)
• Many for one organism
• Binds to a restricted part of the Ag (Epitope)
• Ag has many epitopes (different or repeated)
FlagellumFlagellumH AgH Ag
PiliPiliF AgF Ag
CapsuleCapsuleK AgK Ag
Cell wallCell wallO AgO Ag
CellCellmembranemembrane
Ribonucleo-Ribonucleo-proteinprotein
Structure of a bacterium and the localization of important AgStructure of a bacterium and the localization of important Ag
Cell sap,Cell sap,enzymesenzymes
Gram-positive Gram-negative
0 Ag
Lípid A
Porin
Cell membrane
Cell wallpolysaccharide
Peptidoglycan(*NAG, NAM)
Cell membrane
KDO
The basic structure of cell walls
NAG= N-acetyl glucosamineNAM= N-acetyl muramic acid
EnvelopeEnvelope(lipoproteins(lipoproteins
glycoproteins)glycoproteins)
CoreCore(nucleic acid)(nucleic acid)
CapsomersCapsomers(good Ag)(good Ag)
The structure of a virus (important Ag)
NONMICROBIAL ANTIGENS
CELL-SURFACE ANTIGENSCELL-SURFACE ANTIGENS
Blood group AgBlood group AgAA
AA
ABAB
BB
BB
OO
RhRh
Rh Factor(Rhesus
macacus)
A +/-A +/-
B +/-B +/-
AB +/-AB +/-
O +/-O +/-
RBC
CELL-SURFACE ANTIGENSCELL-SURFACE ANTIGENS
MHC IEndogenous Ag
MHC IIExogenous g
MAJOR HISTOCOMPATIBILITY COMPLEXMAJOR HISTOCOMPATIBILITY COMPLEX
Nucleated cell
WHAT MAKES A GOOD ANTIGEN?
Antigenicity
Chemical Stability
ComplexityParticulate vs. SolubleDenatured vs. Native
Foreignness
Protein.Lipids.CHO’sNucleic acids.
Size
Host genetics
Route ofadministration Dose
Adjuvant
DR. POLLY MATZINGER
An innate sense of Danger
The immune system has two questions to answer when faced with a potentialpathogen.
1. Shall I respond??
2. how does the immune system know what kind of response to make?
Galadriel Mirkwood
1 nm1 nm
GlucoseGlucose
Angiotensin 1.03 kDa Angiotensin 1.03 kDa
Albumin 66 kDaAlbumin 66 kDa
Inmunoglobulin G 160 kDaInmunoglobulin G 160 kDa
Fibrinogen 400 kDaFibrinogen 400 kDa
Inmunoglobulin M 900 kDaInmunoglobulin M 900 kDa
Relative sizes of several Ag
EPITOPE OR ANTIGENIC DETERMINANT(immunodominant region of a molecule)
Microorganism(huge Ag collection)
epitope
HAPTENS(Greek haptein = to grasp or fasten)
DINITROPHENOL = (DNP)
NOT IMMUNOGENICBECAUSE < 1,000 Da
Nativeepitope
Carrierprotein
Several epitopes attached to a peptide chain.
DNPHaptenmolecule
PENICILLIN
EXAMPLES OF HAPTENSEXAMPLES OF HAPTENS
Chronic dermatitis, hair loss, and depigmentation.
EXAMPLES OF HAPTENSEXAMPLES OF HAPTENS
POISON IVY (Rhus radicans) = allergic contact dermatitis
EXAMPLES OF HAPTENSEXAMPLES OF HAPTENS
CHROME
NICKEL
EXAMPLES OF HAPTENSEXAMPLES OF HAPTENS
Resins or latex
Bacteria orFood carrying epitope A
Group A bloodtransfusion
Severe transfusionreaction
Food or bacteria Ag in diet carry epitopes that cross-react with blood group A. Animal of group blood O makes Ab to A epitope despite never having received group A red cells.
Blood group O
Ab to bloodgroup A
