Warning: file_get_contents(https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=28878083
&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 215
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 209.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 243.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 243.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Warning: imagejpeg(C:\Inetpub\vhosts\kidney.de\httpdocs\phplern\28878083
.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 J+Virol
2017 ; 91
(22
): ä Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
How Germinal Centers Evolve Broadly Neutralizing Antibodies: the Breadth of the
Follicular Helper T Cell Response
#MMPMID28878083
De Boer RJ
; Perelson AS
J Virol
2017[Nov]; 91
(22
): ä PMID28878083
show ga
Many HIV-1-infected patients evolve broadly neutralizing antibodies (bnAbs). This
evolutionary process typically takes several years and is poorly understood as
selection taking place in germinal centers occurs on the basis of antibody
affinity. B cells with the highest-affinity receptors tend to acquire the most
antigen from the follicular dendritic cell (FDC) network and present the highest
density of cognate peptides to follicular helper T (Tfh) cells, which provide
survival signals to the B cell. bnAbs are therefore expected to evolve only when
the B cell lineage evolving breadth is consistently capturing and presenting more
peptides to Tfh cells than other lineages of more specific B cells. Here we
develop mathematical models of Tfh cells in germinal centers to explicitly define
the mechanisms of selection in this complex evolutionary process. Our results
suggest that broadly reactive B cells presenting a high density of peptides bound
to major histocompatibility complex class II molecules (pMHC) are readily
outcompeted by B cells responding to lineages of HIV-1 that transiently dominate
the within host viral population. Conversely, if broadly reactive B cells acquire
a large variety of several HIV-1 proteins from the FDC network and present a high
diversity of several pMHC, they can be rescued by a large fraction of the Tfh
cell repertoire in the germinal center. Under such circumstances the evolution of
bnAbs is much more consistent. Increasing either the magnitude of the Tfh cell
response or the breadth of the Tfh cell repertoire markedly facilitates the
evolution of bnAbs. Because both the magnitude and breadth can be increased by
vaccination with several HIV-1 proteins, this calls for experimental
testing.IMPORTANCE Many HIV-infected patients slowly evolve antibodies that can
neutralize a large variety of viruses. Such broadly neutralizing antibodies
(bnAbs) could in the future become therapeutic agents. bnAbs appear very late,
and patients are typically not protected by them. At the moment, we fail to
understand why this takes so long and how the immune system selects for broadly
neutralizing capacity. Typically, antibodies are selected based on affinity and
not on breadth. We developed mathematical models to study two different
mechanisms by which the immune system can select for broadly neutralizing
capacity. One of these is based upon the repertoire of different follicular
helper T (Tfh) cells in germinal centers. We suggest that broadly reactive B
cells may interact with a larger fraction of this repertoire and demonstrate that
this would select for bnAbs. Intriguingly, this suggests that broadening the Tfh
cell repertoire by vaccination may speed up the evolution of bnAbs.