Isolation and Characterization of Poa p I Allergens of Kentucky Bluegrass Pollen with a Murine Monoclonal Anti-Lol p I Antibody

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Abstract
The Poa p I allergens were isolated from the retentate fraction of a dialyzed preparation of an aqueous extract of Kentucky bluegrass pollen by means of a reverse immunosorbent prepared with a murine anti-Lol p I monoclonal antibody, Mab 290-A-167. By sodium dodecyl sulphate-polyacrylamide gel electrophoresis and preparative isoelectrofocusing, Poa p I was found to consist of a 35.8-kD component with an iso-electric point of 6.4 and a 33-kD component with one of 9.1 and designated as Poa p la (acidic) and Poa p lb (basic), respectively. The relative protein content of these components was estimated from the intensity of the stained bands following sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Thus, Poa p la appeared to be the major protein constituent, and on Western immunoblot it also bound the monoclonal antibody to a greater extent than Poa p lb. On the other hand, Poa p lb was shown by Western immunoblot and autoradiographic analysis, to bind to a greater extent the IgE antibodies present in a pool of sera from grass-allergic individuals. Therefore, Poa p lb was considered as the major allergenic component of Poa p I. By competitive inhibition of the radioallergosorbent test, it was demonstrated that the Mab inhibited the binding of Poa p I allergens to human IgE antibodies to the extent of 70%. Hence, it is suggested that Mab and human IgE antibodies recognize identical or closely related determinants of Poa p I allergens.