| Research Abstract |
By a phage-display method, antibody (Fab fragment) expressing phage libraries were constructed from peripheral blood lymphocytes of a patient having high titer of anti-IL-1alpha IgG autoantibodies in her serum. By 4 cycles of panning, anti-IL-1alpha Fab expressing phages were isolated and soluble Fab fragments produced from cloned Fab-phages were examined for their binding to IL-1alpha. Of over 50 Fab clones, only several clones revealed significant binding to IL-1alpha. From these findings, we postulated that misfolding during synthesis of Fab molecules is the reason why low incidence of functional Fab molecules. To examine this possibility, we produced soluble Fab molecules from cloned Fab-phages derived from monoclonal anti-DNA antibody (IgM) producing cell line (NE-1) and examined the bindings of individual Fab clones to DNA.Again, only several Fab clones of over 50 clones revealed weak bindings to DNA.Although soluble Fab were less functional, Fab fragments expressed on phages constantly bound to DNA at very low concentrations (-100ng/ml). Accordingly, Fab molecules expressed on the surface of phages kept functions of antibody activities, whereas soluble Fab molecules were much less functional. From these findings, we consider that the affinity of our recombinant anti-IL-1alpha antibodies (Fab) made by this method may be much higher than the affinity evaluated previously and so we are reevaluating the recombinant anti-IL-1alpha Fab fragments made by this method previously with Fab-phages, but not with soluble Fab molecules. If affinity of the recombinant anti-IL-1alpha Fab expressed on phages is very high, we intend to produce recombinant anti-IL-1alpha IgG molecules by the conventional method for making chimera IgG molecules.
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