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Mapping of Epitopes on <i>Poa </i><i>p</i> I and <i>Lol </i><i>p</i> I Allergens with Monoclonal Antibodies

1990; Karger Publishers; Volume: 91; Issue: 3 Linguagem: Inglês

10.1159/000235120

1423-0097

Zhengwei Lin, A.K.M. Ekramoddoullah, Kuldeep S. Jaggi, Jacqie Dzuba-Fischer, Edward S. Rector, F.T. Kisil,

Food Allergy and Anaphylaxis Research

Allergen <i>Poa p</i> I isolated from the dialysed aqueous extract of Kentucky blue grass pollen by affinity chromatography with an anti-<i>Lol p</i> I murine monoclonal antibody (MAb) 290A-167 was previously shown to consist of a 35.8-kilodalton (kD) component with a pI of 6.4, designated as <i>Poa p</i> Ia, and a 33-kD component with a pI of 9.1, designated as <i>Poa p</i> Ib. The present study reports on the comparative antigenic analyses of these two components, using MAbs produced separately against <i>Poa p</i> I and <i>Lol p</i> I. Thus, anti-<i>Poa p</i> I MAbs 60 and 61 and anti-<i>Lol p</i> I MAb 290A-167 recognized <i>Poa p</i> Ia and <i>Poa p</i> Ib whereas anti-<i>Poa p</i> I MAbs 62, 63 and 64 and anti-<i>Lol p</i> I MAb 348A-6 recognized only <i>Poa p</i> Ia. The specificities of the MAbs were further resolved by comparing their respective abilities to inhibit the binding of ¹²⁵I-<i>Poa p</i> I or ¹²⁵I-<i>Lol p</i> I to the different MAbs prepared in the form of solid phase. These studies revealed that at least 4 distinct epitopes (designated as E₁, E₂, E₃ and E₄) were shared by both <i>Poa p</i> I and <i>Lol p</i> I. All 4 epitopes were present on <i>Poa p</i> Ia whereas only E₁ and E₃ were detected on <i>Poa p</i> Ib. E₁ was recognized by MAbs 60 and 61, E₂ by MAbs 62, 63 and 64, E₃ by MAb 290A-167 and E₄ by MAb 348A-6. The observations that MAb 290A-167 inhibited significantly the binding of human IgE antibodies to <i>Poa p</i> I and <i>Lol p</i> I were interpreted to indicate that epitope E₃ may also constitute an allergenic site on both <i>Poa p</i> I and <i>Lol p</i> I. These studies revealed that <i>Poa p</i> I and <i>Lol p</i> I share extensive antigenic and allergenic cross-reactivities with one another.