Do B-cells and T-cells have to touch?

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2 total messages Started by Axel Boldt Mon, 09 Feb 1998 00:00

#12

Author: Axel Boldt
Date: Mon, 09 Feb 1998 00:00

27 lines
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Hi,

I read a book about immunology but it wasn't clear about the following
question: When a thymus-dependant antigen enters the body for the
first time, it's picked up by APC's and presented to T-cells; the
matching one gets activated and proliferates; the matching B-cell also
picks up the antigen. But the B-cell doesn't in general proliferate
and produce antibodies as a result, it needs the help of T-cells. I
can see 2 scenarios and would like to know which one is correct:

1) The B-cell takes the antigen in, processes it, displays parts of it
   with MHC II, then one of the previously activated T-cells comes
   along, detects the antigen on the B-cell surface, binds to it, and
   B-cell gets activated as a result.

2) Activated T-cell produces and secretes cytokines which reach a
   B-cell that has already captured the antigen and B-cell is
   activated as a result. No physical contact between T and B-cell
   required. (How far-reaching are cytokines anyway? Are they just
   short-distance messengers?)

Problem with 2) is of course that the antigens captured by T- and
B-cell need not have anything to do with each other.

Thanks,
  Axel

Re: Do B-cells and T-cells have to touch?

#13

Author: Jorg Kirberg
Date: Mon, 09 Feb 1998 00:00

62 lines
3187 bytes

In article <xzqra5d1kzf.fsf@dali.uni-paderborn.de>, axel@uni-paderborn.de
(Axel Boldt) wrote:

> 1) The B-cell takes the antigen in, processes it, displays parts of it
>    with MHC II, then one of the previously activated T-cells comes
>    along, detects the antigen on the B-cell surface, binds to it, and
>    B-cell gets activated as a result.
> 
Dear Axel,
that's the correct one. Only I think it is simplistic to say that the B cell
gets 'activated as a result' of T cell binding. Rather the T cell starts
to secrete lymphokines (that are SHORT range molecules) which allow the B
cell to continue.

In terms of references: Look for Mitchison, N.A. some thirty years
ago. That's what I found and therein you might find cited more useful stuff:
%A Mitchison, N. A.
%D 1990
%T An exact comparison between the efficiency of two- and three-cell-type
clusters in mediating helper activity
%B Eur J Immunol
%V 20
%N 3
%P 699-702
%K Animal
Antibody Formation
B-Lymphocytes/cy [Cytology]
*B-Lymphocytes/im [Immunology]
Dose-Response Relationship, Immunologic
H-2 Antigens/im [Immunology]
Immunization, Passive
In Vitro
*Lymphocyte Cooperation
Mice
Minor Histocompatibility Loci
T-Lymphocytes, Cytotoxic/cy [Cytology]
*T-Lymphocytes, Cytotoxic/im [Immunology]
T-Lymphocytes, Helper-Inducer/cy [Cytology]
*T-Lymphocytes, Helper-Inducer/im [Immunology]
%X Adoptive transfer of anti-H-2Db-primed B cells combined with anti-minor
histocompatibility antigen-primed T cells enables the effect of linked and
unlinked alloantigen to be compared. Over an extensive dose range the
unlinked antigen proved ineffective. In a previously described, exactly
comparable system for assessing the same effect on cytotoxic T cell
precursors, low doses of linked antigen had proved approximately equally
effective, but high doses of unlinked antigen had proved effective. This
contrast supports the hypothesis that whereas T-B collaboration is
mediated by two-cell-type clusters, collaboration between T cells requires
formation of three-cell-type clusters.

jorg

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