Immunology

Immunology

• Purpose of the immune system:– Discriminate self from non-self

• Non-self –Antigens

• Immunity:– All mechanisms used by the host to protect itself

and fight non-self

Non-Self - Antigens• Anything that can react with the participants

of the immune system– Ex. antibodies

• Epitope: Characteristic of the antigen which allows its recognition as being non-self– Ex. Lipids, proteins, lipopolysaccharides

The Antigen

Virus=Antigen

Epitopes

Immunological Diagnostic Methods

• Determine the presence of an antigen:• An organism• A protein• A toxin• An antibody

– ELISA method to determine quantity– Immunochromatography (Rapid tests)

ELISA

• Used to detect the presence of antigens or antibodies– High sensitivity– Quantitative

ELISAMethod

ENZENZ ENZENZENZENZ ENZENZ ENZENZ

ENZENZENZENZ

ENZENZENZENZ ENZENZ

Serum (source of Ag) is added to plastic wells

Antigen PresentAntigen Present Antigen AbsentAntigen Absent

Blocking agent addedAb against AgAg is addedWashDetecting Ab addedWashSubstrate added

Interpretation of Results• Serums of patients tested for the presence of HIV

– 1o Ab anti-HIV from mouse– 2o Ab anti-Ab of mouse

• Conclusions– Patients 1 & 3 are positive for HIV

– Patient 3 has a higher titer

– Patient 2 is negative for HIV

1/2 1/4 1/8 1/16 1/32 1/64 1/128Control serums + —

1/8

Immunochromatography Method

9

Interpretation

10

Positive Negative Invalid