re re real function, naive bcells and somatic m.

Ephraim Fuchs ejf at welchlink.uoregon.edu
Sat Jun 10 05:10:38 EST 1995


Paul J Travers (p_travers at icrf.icnet.uk) wrote:
: In article <3r8gob$mdl at jhunix1.hcf.jhu.edu>, ejf at welchlink.uoregon.edu
: (Ephraim Fuchs) wrote:


: Ephraim,

:       I suspect your statement is a little too general.  How do you
: account for the observation that inherited deficiencies in late (ie lytic
: pathway) complement components are specifically associated with
: susceptibility to Neisseria infections (a gram- organism).  In these cases
: the early complement components are intact and capable of acting as
: opsonins, but this is insufficient to control this particular group of
: pathogens.

:       As to whether in general adaptive immune responses are associated
: with resistance to gram- bacteria, isn't there a window of susceptibilty
: in infants whose onset correlates with the disappearance of maternal
: immunoglobulin and which decays as the infants own immunoglobulin levels
: rise?  Does this not suggest that antibody (which I would class as part of
: the adaptive immune system) plays a role in host defence against gram-
: pathogens?


Paul,

You are absolutely correct in that I am being too general in my 
statement.  There are gram - bacteria against which antibodies, but not T 
cells, play a useful role-for instance, Pneumococcus, Hemophilus 
Influenzae, and Neisseria spp.  If I remember correctly (and it has been 
a very long time since I have had any instruction in infectious 
diseases), this is because these organisms are encapsulated and contain 
antigenic polysaccharides (which of course cannot be recognized by T 
cells) in their capsules.  But consider your "typical" gram negative 
organism, like E. coli, Pseudomonas, Enterobacter, Serratia, etc.  
Against these organisms I would propose that the adaptive immune system 
plays no role, and an individual that has survived an infection with one 
of these organisms has no better chance of surviving a reinfection than 
the first time around.  This is why I believe that the induction of 
"costimulatory" molecules by LPS of gram negative bacteria cannot be very 
useful.

By the way, didn't you write a textbook with Charlie Janeway?  Should I 
buy it?

Ephraim Fuchs
ejf at welchlink.welch.jhu.edu





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