Linkage of low and high affinity anti-fluorescein idiotype families.

Data presented in this study describes the isolation and characterization of two anti-fluorescein (F1) hybridoma proteins 3-24 and 12-40, both IgG1, kappa with a Ka = 2.8 and 3.4 X 10(6) M-1, respectively, at 37 degrees C. These clones inhibited (6.8 +/- 2.8 -20.8 +/- 0.6% at 1 microgram/well) the idiotype-anti-idiotype interactions (IAII) of anti-F1 clones 3-13 and 3-17, which define a previously described low affinity idiotype family. Antibodies 3-24 and 12-40 also inhibited (45.0 +/- 3.0 and 61.3 +/- 5.6%, respectively, at 1 microgram/well) an IAII defined by a high affinity (Ka = 5.2 +/- 1.5 X 10(9) M-1 at 37 degrees C) anti-F1 clone, 4-4. Hybridoma proteins 3-13 and 3-17 possess similar affinities for F1 (Ka = 3.8 +/- 5.1 and 5.9 +/- 4.0 X 10(4) M-1) and are known to be idiotypically unrelated to clone 4-4. While 3-24 and 12-40 appeared very similar, non-identity of their active sites was established by heterologous idiotypic inhibitions, fine specificity of binding and spectral measurements (Qmax and lambda max) of bound F1. All IAII (3-13, 3-17, 9-40 and 4-4) were inhibited greater than 80% by the presence of 10(-4) M F1 or F1-BSA. In addition, four intermediate affinity (6.0 X 10(6) less than or equal to Ka less than or equal to 5.3 X 10(8) M-1) anti-F1 clones, comprising a second previously described idiotype family (designated the 9-40 family) were further analyzed. Inhibition of the 9-40 IAII by all heterologous proteins in the 9-40 family (except clone 5-27), and clones 3-24, 12-40 and 4-4 ranged from 87.7 +/- 1.3 to 95.4 +/- 1.0% at 1 microgram/well. Titration of the 9-40 IAII inhibition by antibodies 9-40, 3-24, 12-40 or 4-4 generated essentially superimposable profiles. In reciprocal inhibition experiments, using the 4-4 IAII, clones 3-24, 12-40, 9-40 and 4-4 gave distinct idiotypic titration patterns. Thus, members of the 9-40 family, 3-24 and 12-40 were more closely related to intermediate affinity clone 9-40 than high affinity clone 4-4.(ABSTRACT TRUNCATED AT 400 WORDS)