Preparation and characterization of antibodies to the λ chain variable region (V_λ) of mouse immunoglobulins

Abstract

Abstract The variable portion (V L ) of the mouse myeloma protein MOPC‐315 (α, λ 2 ) was obtained from its Fv fragment and was used to immunize rabbits. Anti‐V L antibodies were found to be specific to the V L region of protein 315 and to precipitate V L , Fv or light chain but not Fab' or intact M315. Anti‐V L 315 precipitates also the light chain of MOPC‐104E (μ, λ 1 ) but not the intact protein. Intact immunoglobulins (Ig) containing λ chains, although they do not precipitate with anti‐V L , inhibit the binding of anti‐V L to V L in the radioimmunoassay. Radioimmunoassay inhibition studies demonstrated that V λ1 and V λ2 cross‐react extensively and that anti‐V L 315 can be used as a general anti‐V λ reagent to detect molecules containing λ chains in mouse serum. Analysis of sera from several mouse strains indicated that V λ ‐containing molecules are present in approximately 3% of the Ig population, whereas the SJL strain has no detectable V λ ‐bearing molecules. In some of the antisera, anti‐V L 315 slightly cross‐reacted with V K ‐bearing molecules. Anti‐V L 315 antibodies are not anti‐idiotypes since they react with myeloma proteins M315 (anti‐2,4‐dinitrophenyl MOPC‐104E (anti‐dextran) and HOPC‐1 (specificity unknown) and with most serum Ig containing λ chains. In view of the similarity of mouse λ chain sequences, it is suggested that most anti‐V L 315 is “anti‐framework” antibody.