Human α-fetoprotein epitopes as revealed by monoclonal antibodies

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Thirty monoclonal antibodies (MoAbs) to human α-fetoprotein (AFP) were compared with one another by two methods: Immunoaffinity electrochromatography or additive ELISA. The first method permitted to analyse the epitopes of native AFP in solution [Abelev et al., Immunol Lett 1994;40:133–138] while the other approach also detects the epitopes of conformationally modified (partly denatured) AFP fixed on the plastic [Yazova et al., Immunol Lett 1990;25:325–330]. Competitive analysis of all MoAbs revealed 10 epitopes, 9 expressed on native AFP and 1 only on the partly denatured molecule. The cross-reactions between separate MoAbs allowed to include them into 6 distinct epitope clusters, or immunodominant groups with the characteristic patterns of reactivity. The obtained epitope map of AFP is necessary for the construction of AFP detection kits as well as for the identification of its antigenic and functional subfractions.

Section: Discussionmentioning

confidence: 51%

Section: Additive Test In Elisamentioning

confidence: 99%

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Epitope Mapping of Human Alpha-Fetoprotein

Yakimenko¹,

Karamova²,

Goussev³

et al. 1998

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“…MAbs to AFP were prepared in our laboratory as described earlier [13] or were obtained from the anti-AFP MAb collection of the TD-2 workshop of the International Society of Oncodevelopmental Biology and Medicine [14]. The MAbs used in this work were categorized into 5 discrete groups (A, B, C, D, and E) based on their respective epitopes.…”

Section: Monoclonal Antibodiesmentioning

confidence: 99%

New Approaches for the Detection and Characterization of Alpha-Fetoprotein Epitope Variants

Karamova¹,

Yazova²,

Yakimenko³

et al. 2003

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Alpha-fetoprotein (AFP) is an embryo-specific protein of mammalian sera that consists of a single glycosylated polypeptide chain (∼70 kD) with 5–6 epitope clusters located on the native molecule. We have elaborated three approaches for the separation of AFP into fractions (variants) that are different in the distinct epitope expression on the native molecule. For this, we have used three technologies largely based on immunoaffinity electrochromatography and electrophoresis/immunoblotting. The separation of these variants was facilitated using monoclonal antibodies previously characterized to the 5 epitope clusters and two individual epitopes on AFP in the ISOBM international workshop. We have shown that these approaches facilitate the identification of cryptic epitopes in AFP, and the relevance of these findings is discussed.

“…MoAbs to hAFP were obtained by Yazova et al [14], characterized and mapped to the AFP molecule [12]. The MoAbs D 10 , F 5 and F 2 , directed to three noncross-reacting epitopes, were used in that work.…”

Section: Monoclonal Antibodiesmentioning

confidence: 99%

Conformational Variants of Human Alpha-Fetoprotein

Karamova

Yazova²,

Goussev³

et al. 1998

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The immunological heterogeneity of human α-fetoprotein (AFP) was demonstrated using immunoaffinity electrochromatography on monoclonal antibodies (MoAbs) to 3 non-cross-reacting epitopes of this protein. At least 4 subfractions expressing different epitopes were found in the native AFP. These subfractions demonstrated molecular weights similar to the major component of the original AFP. The difference between epitope F₅-positive and F₅-negative subfractions disappeared when epitope-negative subfraction was conformationally changed after fixation onto nitrocellulose membrane (NCM). Thus, the epitope under study exists in two forms on the native human AFP molecule: an open and a cryptic form. The cryptic form could be revealed after partial denaturation by fixation on NCM. The epitope variants of AFP could possess different functions in multifunctional AFP. The AFP epitope heterogeneity found in this work should be taken into account when constructing diagnostic AFP kits and when isolating purified AFP using anti-AFP MoAbs.