first a review…
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First a review…. Adopt as a perspective that: One B-cell produces one antibody Make that perspective more exacting: One B-cell produces one idiotype . Cassettes (V, J, [D],) ( aka gene segments ) “fuse” ( to make an idiotype ). - PowerPoint PPT PresentationTRANSCRIPT
IMMUNOLOGY
Bios 328a textbook-based study of immunologySpring 2003
http://www.lehigh.edu/~sk08/Courses/Bios328/mainpage.htm
First a review…Adopt as a perspective that:
One B-cell produces one antibody
Make that perspective more exacting:One B-cell produces one idiotype.
Cassettes (V, J, [D],) (aka gene segments) “fuse” (to make an idiotype).
Fusing occurs because RAG recognizes one turn/two turn signals on cassettes.
CDR3 develops through junctional flexibility (trimming) and addition of P & N nucleotides (expanding).
CDR1 and CDR2 (especially) and CDR3 become more varied
because of somatic hypermutation.
First a review… now with images
And, I will use images from a different source.
Remember to be critical of what “interpretative” drawings convey…
First a review… now with images
First a review… still with images
RAG: what does it do? …how does it work?
First a review… still with more images
RAG: what does it do? …how does it work?
…what about P&N nucleotides?
PART IV (some new stuff)• How do immunoglobulins assemble?
• Some immunoglobulins are in the surface membrane of immature B-cells while other immunoglobulins of the same idiotype are secreted by mature B-cells. What’s the difference?
• Similarly, identical variable regions can be shared among different isotypes. How?
• B-cells are diploids with two sets of genetic instructions. How does just one set get expressed?
How do immunoglobulins assemble?
Some immunoglobulins are in the surface membrane of immature B-cells while other immunoglobulins of the same idiotype are secreted by mature B-cells. What’s the difference?
Similarly, identical variable regions can be shared among different isotypes. How?
B-cells are diploids with two sets of genetic instructions. How does just one set get expressed?
The general scheme of B-cell development
• STEM CELL
• pro (genitor) Bcell
• pre Bcell
• Ag-selected ( stimulated)- Bcell
• Ab secreting plasma cell