In the present report we have isolated by affinity chromatography a putative human Fab2 that binds to human Fab2. We have examined the binding specificity of the Fab2 anti-Fab2 to IgG, Fab2, Fab, and Fc fragments derived from various species IgG and have attempted to isolate species-specific antibody by affinity chromatography. The results obtained in this study using 125I-Fab2 anti-Fab2 demonstrate that the natural antihuman antibodies cannot be separated into IgG species-specific population. Moreover, subjecting affinity-isolated Fab2 anti-Fab2 to a Sepharose 4B-mouse IgG column failed to remove mouse IgG-specific binding activity. These data suggest that the human natural antibodies, ie, Fab2 anti-Fab2 recognize homology epitopes (domain) and not species-specific IgG epitopes. The observation that Fab2 anti-Fab2 reacts with the Fc fragment as well as Fab supports this hypothesis. Additionally, the binding specificity of the Fab2 that was bound (fractions 30-35) by the Sepharose 4B-mouse IgG column exhibited the same reactivity as the nonbound fractions 5,6. The observation that Fab2 that were bound by the Sepharose 4B-mouse IgG suggest that this population contained molecules with higher binding affinities than the Fab2 in fractions 5,6.
|Original language||English (US)|
|Number of pages||2|
|Issue number||1 SUPPL. 1|
|State||Published - Jan 1 1988|
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