Self vs Non-self

Recognition of: Self vs Non-self Presence vs Absence Harmless vs Dangerous

hematopoiesis pluripotent

What’s wrong with this fruit fly? Missing toll or other members of the toll pathway

Is it dangerous?

Involution of the thymus

Another accident with chickens • 1956: Bruce Glick “accidentally” vaccinates bursectomized chickens • Finds they make poor antibody responses

The lymphocyte

Antigen receptors assembled by somatic recombination 2 Light chains (IgL) b, d a, g Heavy chain Light chain 2 Heavy chains (IgH) Variable domain Constant domain TCR or T Cell Receptor Ig or B cell receptor

Antigen

Germline DNA Recombination 3 1 2 1 2 3 3 1 3 Transcription –Splicing -Translation Transcription –Splicing -Translation Recombination 2 2 3 2 1 2 3 Protein: T Cell Receptor Germline DNA Generation of Diversity in Antigen Receptors Vn V3 V2 V1 D  JC T cell V D J C V J C Vn V3 V2 V1 JC

Fig 8-8

Recognition of: Self vs Non-self Presence vs Absence Harmless vs Dangerous How is self-tolerance maintained?

Frank Macfarlane Burnet* Believed any correct theory must explain: • How antigen selects correct specificity • Why only a single specificity is produced • How self tolerance is maintained • Why second response to same antigen is so much larger than the first *1958 Nobel Prize

Clonal Selection Theory • Each cell is a unique clone with its own specificity • If the cell encounters Ag in a premature state, it dies • The mature pool of cells represent those that did not encounter the Ag they are specific for during development • When mature cell encounters Ag it begins to divide (clonal expansion) = foreign antigen

Fig 8-8

Mice & Cattle Mice & Primates Primates & Cattle

Fig 12-5

Self vs Non-self

Télécharger la présentation

Plus de contenu associé