The humoral immune response against α(1→3) dextran (Dex) in BALB/c mice is characterized
by the formation of predominantly IgM antibodies bearing the J558 idiotype. IgG antibodies
do not appear in euthymic mice. In athymic animals however, the response proceeds to
a vigorous IgG production. In euthymic mice formation of IgG is suppressed by J558 idiotype-
specific regulatory T cells recognizing in association with I-Ed and in cognate T/B interaction
the VH CDR3 derived peptide of the J558 idiotpye. Only B-2 lymphocytes produce
IgG whereas B-1 cells do not participate in the production of this Ig class. Using a novel synthetic
all α(1→3)-D-gluco configurated tetrasaccharide the Dex-specific B cells can for the
first time be analyzed in FACS. In experiments using this newly designed low molecular Dex
no signs of B cell apoptosis can be found. This demonstrates a true silencing of persisting Bγ
memory cells and supports previous by adoptive transfer experiments. In this suppression an
involvement of CD28/B7–1 interaction can be demonstrated which is a necessary costimulatory
suppression signal in addition to the cognate TCR/peptide-I-Ed interaction between J558
Id-specific T cells and J558 idiotype beating B cells. This results in an activation of 178–4 Ts
cells, leading to an overall suppression of the Dex-specific IgG isotype production on the one
hand and on the other hand provides a signal for the survival and clonal expansion of J558
Id-positive B cells.
Copyright
Copyright © 2001 Hindawi Publishing Corporation. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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