Diversity vs Specificity (Bowden) Flashcards
What stages are lymphocytes when found in generative organ(BM or thymus)
Stem Cell, Pro-lymph Pre-lymph and immature lymphocytes
What stage of lymphocyte development is it self-antigen dependent
when transitioning from immature to mature
What is the Immune Repertoire concept
that a person makes more different forms of Ab than all other proteins combined
Describe clonal selection
Gene rearrangement events occur in absence of Ag
When are clones activated
by specific antigens
What are the 2 mechanisms of Primary Ig Rearrangement
Multiple germ line genes: Combinatorial diversification
Junctional diversity
What is the mechanism for secondary Ig rearrangement
Somatic hypermutation
What cytokines play a role in converting stem cell to pro -B
IL3 and IL7
What enzymes are expressed to convert pro-B into Pre- Bcell
Rag and TdT
What phase in B cell maturation does recombination occur
Between pro-B and pre-B
What are the CD markers for Pro-B cells
CD43+ CD19+ CD10+
Where is the H chain locus and what are its components
chromosome 14 Variable regions n~100 with leader exon in front. Diversity regions n~23 Joining regions Constant regions
Where is the kappa light chain locus and describe gene
chromosome 2
Variable regions n~35 with leader exon in front
Joining regions n~5
1 constant region C kappa
Where is the lambda light chain locus and describe gene
chromosome 22
Variable regions n~30 with leader exon in front
Joining regions n~4 in front of constant regions
Constant regions n~4
What is encoded for in the Constant regions of the heavy chain
each class and subclass of immunoglobulin, one for hinge other for domain
Explain allelic Exclusion
maternal or paternal chromosome. not both
heavy chain can be from either chromosome, and the light chains can be from either chromosome.
Why do we need allelic exclusion
expression of both alleles would render B cell multispecific
DNA Rearrangements of making heavy chain
one of the D regions at random is joined with one of the J regions. Then one of the V genes is rearranged to the D/J region
How does the DNA H chain become transcriptionally active
Promoted associated with V gene is borught close the enhancer which is between J and Cmu region.
Two ways pre-mRNA of H chain is processed
VDJ next to C mu gene(IgM) or VDJ next to Cdelta (IgD) coding then for either mu chain or delta
Where do the heavy and light chains assemble together
in the ER
What are the recombination signal sequences
they flank the V J and D exons
What is the struture of each RSS
conserved nonamer and heptamer that are separated by either 12 or 13 base pairs. so either one or two turns of the DNA helix
Where does recombination of the RSS usually occur
between a 1 turn and 2 turn signal
