natural antibodies
DESCRIPTION
Natural Antibodies. Made by B-1 cells*. * Self replenishing B cells that differ in phenotype, location and ontogeny from B-2 cells (the majority B cell population). Natural Antibodies. Present in unimmunized mice Bind to pathogens and cell components A key part of the innate immune system - PowerPoint PPT PresentationTRANSCRIPT
Natural Antibodies
Made by B-1 cells*
* Self replenishing B cells that differ in phenotype, location and ontogeny from B-2 cells (the majority B cell population).
Natural Antibodies
Present in unimmunized mice
Bind to pathogens and cell components
A key part of the innate immune system
spontaneously secreted (as natural IgM)
first line of defense against invading pathogens
Anti-PtC repertoire
Antibodies expressed by 5-15% of B-1 cells bind PtC
Other (B-2) cells do not make anti-PtC antibodies
Ig heavy chains in anti-PTC antibodies are mainly encoded by 3 VH families; VH11, VH12, VHQ52
PtC-binding B cells are detectable by Hi-D FACS
PtC-binding B cells are detectable by Hi-D FACS
IgMa and IgMb are IgM allotypes present respectively in the Balb/C and C.B/17 allotype congenic strains
Is the difference due to enviromental influences (selection)
or to
genetic differences between the two strains?
TRANS VS cis
Genetic Control of the Natural Antibody Repertoire
Cis-linked Regulation of Antibody Variable Gene Usage
BALB/c x C.B-17 F1 Mice
BALB/c x C.B-17 F1 Mice
Determining the VH repertoire of anti-PtC antibodies
Single-cell RT-PCS and sequencing of PtC binding cells
FACS analysis of PtC binding cells
Cis-linked regulation of VH12 Predominance
Summary and Conclusions
VH12 predominates the anti-PtC repertoire in C.B-17 mice while VHQ52 predominates in BALB/c
VH predominance is controlled in cis
The element(s) that controls the predominance maps to the VH encoding region.
SummaryTwo VH12 Alleles
Differ by a single amino acid in framework 1 (codon 21)
The VH12ala (alanine) is found in BALB/c and C57BL/6
The VH12thr (thronine) allele is found in the BALB/c Igh bcongenic strain, C.B-17, and in C57BL/10-related strains (including B102a4b from which CH lymphomas were isolated)
Proteins encoded by two VH12 alleles differ by a single amino acid at codon 21 in framework
6 silent mutations also distinguish the VH12 alleles BALB/c and C.B-17
VH12 Predominance Maps to the VH Region
But selection is also important in determining the
B-1 repertoire
VH12 has higher avidity for PtC liposomes than VH12ala
Cells expressing VH12thr antibodies that do not bind PtC do not increase in
frequency with age
Differential VH expression in PtC-binding cells from C.B-17 x BALB/c heterozygotes
SummaryAll VH anti-PtC except VH12thr
Frequency among peritoneal B cells is fixed by 3-4 weeks of age and remains stable at least until 7 months
VH12thr
Frequency among peritoneal B cells increases consistently from 3-4 weeks of age at least 7 months
Acknowledgements
Lee Herzenberg Len Herzenberg
Jennifer Wilshire Nicole Baumgarth
Darren Gold
The Members of the Herzenberg Laboratory
The Stanford Shared FACS Facility
B-1
* Self replenishing B cells that differ in phenotype, location and ontogeny from B-2 cells (the majority population).