| Abstract |
Eighteen monoclonal anti-fluorescein (Fl) antibodies from BALB/cV mice
were characterized and 13 possessed a low affinity for Fl (Ka = 5 x 10^4
M^-1) while 5 had a higher affinity (Ka = 5 x 10^8 M^-1). Eleven of the 13
low affinity clones were idiotypically cross-reactive (40-100%) and 4 of
these clones possessed identical idiotypes (Ids) (3-12, 3-13, 3-17 and 3-35).
Heavy and light chains derived from clones 3-12, 3-13 and 3-17 and
used in recombination experiments, resulted in the reformation of an anti-
Fl active site in all six heterologous combinations. The expression of Ids
3-13 and 3-17 in the Io, IIo or IIIo polyclonal anti-Fl response was
quantitated and found to represent <1.0% of the specific repertoire. Ids
3-13 and 3-17 were expressed in 15/22 ad 22/28 individual mice, respectively.
Clones 3-13 and 3-17 had similar though not identical active sites as
determined by fine specificity of binding and Id inhibitions. Ids 3-13 and
3-17 represent the first demonstration of repertoire-specific recurrent
Ids expressed during a T-dependent immune response lacking a dominant Id.
Antibodies 3-13 and 3-17 were idiotypically cross-reactive (10-40%) with 6
other anti-Fl clones (designated the 9-40 family) which possessed a higher
affinity for Fl (Ka = 5 x 10^6 M^-1). Members of the 9-40 family were also
idiotypically cross-reactive with a single high affinity clone 4-4 (Ka = 5
x 10^9 M^-1). This idiotypic linkage provided a greater span in affinity
(>20,000 fold) than in all previously characterized Id families within
restricted or unrestricted immune responses. The sequence of antibody 3-13
V(H) region was determined by genomic cloning and amino acid sequencing
and was 78% homologous to the (alpha)-1,3-dextran binding myeloma proteins
J558 and 104E. Rearrangement of a V(H) gene homologous to 3-13 was
required idiotypically cross-reactive clones and in no idiotypically
distinct clones.
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