B-Cells - Why one specificity?

Jim Kling jkling at nasw.org
Tue Dec 9 10:23:22 EST 1997


Bob Scibienski wrote:
> 
> In fact, "two" specificities equates with four possible L + H chain
> combinations, so the waste grows exponentionally.
> 
> Bob S.
> 
> John Richard Seavitt <jrseavit at artsci.wustl.edu> wrote:
> 
> >On Tue, 9 Dec 1997, Andrew Louka wrote:
> 
> >> Why one B cell, one specificity?  Why not have multiple specificities per
> >> B cell - surely this would have been more effective (and energy efficient!).
> 
> >Nope.  Then you'd have B cells with two or more specific surface
> >immunologlobins.  Since the B cell couldn't distinquish which one it got
> >activated through, it would presumably behave as if all of its receptor
> >specificities had been activated.  It would await T cell help,
> >proliferate, and differentiate into plasma cells.  Of course, it would now
> >be spending the metabloic energy to produce two or more specific secreted
> >antibodies.
> 
> >Of course, the odds that the appropriate antigens are present for more
> >than one of the antibodies is low, and so the extra production is waste.
> 
> >John Seavitt
> 
> >P.S.  The current setup also allows the use of allelic exclusion to select
> >functional rearrangements in BCR genes, which would no longer be a
> >possible strategy for a multispecificty B cell.

All true -- but what if, along with being able to present two types of
antibody, the B cell had two transmembrane signalling cascades, one for
each antibody? That would allow it to distinguish which antibody had
been activated.

I suspect the reason it hasn't worked out this way may have as much to
do with the process by which humoral immunity evolved. Any evolutionists
out there want to take a crack at the question?

-- 
Jim Kling
Writer and Consultant
jkling at nasw.org
http://nasw.org/users/jkling

also volunteer Public Relations Guy
the Creative Concepts Ice Project
“building a community for youth through hockey”
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