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Antibody Class Switching.
Presentation by: Gidwani Manish N.
Roll No.: 147905.
1CHARLIE.
What Is Ab Class Switching?
• a biological mechanism that changes a B cell's production
of immunoglobulin (antibodies) fro...
Antibody Gene Arrangement.
CHARLIE 3
“Switching” to these classes requires
DNA recombination and is distinct from
V(D)J re...
Ab Gene Arrangement (Contd.)
CHARLIE 4
Mechanism of Class Switching by Gene
Rearrangement.
CHARLIE 5
Ab Class Switch in B-Cell by Cytokine
mediated Response.
CHARLIE 6
(from CD4 T cells)
Processing of Genes Re-arranged.
• Double-stranded breaks are generated in DNA at conserved nucleotide motifs,
called swit...
Summary.
CHARLIE 8
References.
• Janeway CA Jr., Travers P, Walport M, Shlomchik MJ
(2001). Immunobiology. (5th ed.). Garland Publishing.(via...
Thank You.
CHARLIE 10
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Antibody class switch ppt

  1. 1. Antibody Class Switching. Presentation by: Gidwani Manish N. Roll No.: 147905. 1CHARLIE.
  2. 2. What Is Ab Class Switching? • a biological mechanism that changes a B cell's production of immunoglobulin (antibodies) from one class to another, such as from the isotype IgM to the isotype IgG. • the constant-region portion of the antibody heavy chain is changed, but the variable region of the heavy chain stays the same. • the variable region does not change, class switching does not affect antigen specificity. Instead, the antibody retains affinity for the same antigens, but can interact with different effector molecules. CHARLIE 2
  3. 3. Antibody Gene Arrangement. CHARLIE 3 “Switching” to these classes requires DNA recombination and is distinct from V(D)J recombination.
  4. 4. Ab Gene Arrangement (Contd.) CHARLIE 4
  5. 5. Mechanism of Class Switching by Gene Rearrangement. CHARLIE 5
  6. 6. Ab Class Switch in B-Cell by Cytokine mediated Response. CHARLIE 6 (from CD4 T cells)
  7. 7. Processing of Genes Re-arranged. • Double-stranded breaks are generated in DNA at conserved nucleotide motifs, called switch (S) regions, which are upstream from gene segments that encode the constant regions of antibody heavy chains; these occur adjacent to all heavy chain constant region genes with the exception of the δ-chain. • DNA is nicked and broken at two selected S-regions by the activity of a series of enzymes, including Activation-Induced (Cytidine) Deaminase (AID), uracil DNA glycosylase and apyrimidic/apurinic (AP)-endonucleases. The intervening DNA between the S-regions is subsequently deleted from the chromosome, removing unwanted μ or δ heavy chain constant region exons and allowing substitution of a γ, α or ε constant region gene segment. • The free ends of the DNA are rejoined by a process called non-homologous end joining (NHEJ) to link the variable domain exon to the desired downstream constant domain exon of the antibody heavy chain. In the absence of non- homologous end joining, free ends of DNA may be rejoined by an alternative pathway biased toward microhomology joins. With the exception of the μ and δ genes, only one antibody class is expressed by a B cell at any point in time. CHARLIE 7
  8. 8. Summary. CHARLIE 8
  9. 9. References. • Janeway CA Jr., Travers P, Walport M, Shlomchik MJ (2001). Immunobiology. (5th ed.). Garland Publishing.(via NCBI Bookshelf) • Stavnezer J, Amemiya CT (2004): Evolution of isotype switching. Semin. Immunol. 16 pg: 257–75. • Eleonora Market, F. Nina Papavasiliou (2003): V(D)J Recombination and the Evolution of the Adaptive Immune System . PLoS Biology. CHARLIE 9
  10. 10. Thank You. CHARLIE 10

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