8: Antibody Diversity Flashcards
Plasma cells
terminally differentiated and activated B cells that secrete antibodies
What cells in bone marrow stimulate B cell differentiation?
stromal cells
What is antibody gene rearrangement called?
V(D)J recombination
V genes
variable
J genes
joining
D genes
diversity
What 2 genes recombine first?
D and J
What region is not present in light chains?
D
Recombination activating genes (RAG)
drives gene rearrangement
Multiple germline gene exons
both heavy and light chains may be encoded by multiple variable region DNA segments that are spliced together to form the variable exon region
H and L chain combinations
the antigen binding site is formed by the interaction of both chains, and any given H chain can dimerized with any given L chain
Imprecise joining of segments
during somatic rearrangement, the gene segments for a variable region can be spliced together using any of several nucleotides
Random insertion of bases
during splicing, nucleotide bases can be randomly inserted into the splice junction, changing the codon frame
Somatic hypermutation
areas within the variable regions are subject to germline base substitutions during cell division
What is the only diversity mechanism that occurs after a B cell encounters its specific antigen?
somatic hypermutation
Receptor editing
when an antibody is created that binds to self antigens, the B cell may try another recombination
Allelic exclusion
successful rearrangement of the antibody gene DNA is a random event which occurs only on one chromosome for each light or heavy chain genes
What does allelic exclusion assure?
that each individual B cell generates only a single antibody molecule
Which chain rearranges first?
heavy
