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 γ3. The RF bound specifically to the MRL γ2a allotype (lgh-1(j)) but not to the B6 γ2a allotype (Igh-1b). The germ-line antibody was also found to bind γ2a 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.
|Original language||English (US)|
|Number of pages||11|
|Journal||Journal of Immunology|
|State||Published - May 1 1994|
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