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Jacobson BA , Sharon J , Shan H , Shlomchik M , Weigert MG , Marshakrothstein A
An Isotype Switched and Somatically Mutated Rheumatoid-Factor Clone Isolated from a Mrl-Lpr/Lpr Mouse Exhibits Limited Intraclonal Affinity Maturation
Journal of Immunology. 1994 May 1;152(9) :4489-4499
PMID: ISI:A1994NG71900027   
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Abstract
Employing site-directed mutagenesis we have reconstructed and expressed the germ-line precursor of an expanded rheumatoid factor (RF) clone. This RF clone, designated clone F, was isolated from an autoimmune MRL/MpJ-lpr/lpr mouse. Most of the clone members were extensively mutated and isotyped-switched. The predominant isotype of clone F was gamma 3. The RF bound specifically to the MRL gamma 2a allotype (lgh-1(j)) but not to the B6 gamma 2a allotype (Igh-1(b)). The germ-line antibody was also found to bind gamma 2a in an RF assay. The affinities of the germ-line RF and representative members of the clone were measured in an ELISA-based equilibrium binding assay. The dissociation constant (K-d) of the germ-line RF was 2.5 x 10(- 6) M. All of the expressed clone members had affinities within a two- to sixfold range of the germ line, indicating that the mechanisms of somatic hypermutation and selection resulted in only limited affinity maturation of this autoantibody clone.
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English Article NG719 J IMMUNOL