| 1. |
- Nilsson, Bo, et al.
(författare)
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Distinctive expression of neoantigenic C3(D) epitopes on bound C3 following activation and binding to different target surfaces in normal and pathological human sera
- 1989
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 26:4, s. 383-390
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Tidskriftsartikel (refereegranskat)abstract
- Binding of C3 to sheep erythrocytes in a serum-free milieu (EAC14oxy2, EAC142) has previously been shown to mimic the antigenic change that occurs upon denaturation of C3 in sodium dodecyl sulphate (SDS), whereby neoantigenic C3(D) epitopes are exposed. The present paper deals with C3 bound to various target surfaces which are known to modulate the functional properties of C3 in different ways. Bound C3 fragments on serum-treated human aggregated gammaglobulin, zymosan, rabbit and sheep erythrocytes, and on circulating immune complexes isolated from sera of patients with rheumatoid arthritis and systemic lupus erythematosus, were shown to be mainly in the iC3b form. By RIAs, employing polyclonal antibodies, the range of C3(D) antigenic epitopes of 125I-labelled SDS denatured C3 expressed by the particle-bound iC3b was monitored. The physiologically bound iC3b on all tested particles expressed wide ranges of C3(D) epitopes and each type of particle-bound C3 exposed its individual range. By competition ELISA specific C3(D)α epitopes were monitored, employing monoclonal antibodies. A distinct difference in the expression of these epitopes was observed in iC3b bound to various test particles in the presence of normal serum and in iC3b present on circulating immune complexes from pathological sera. Considering that the neoantigenic C3(D) epitopes have been shown to be associated with different functions of C3, the distinctive antigenic expression of each type of serum-treated particle might reflect different functional forms of the protein.
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| 2. |
- Nilsson, B, et al.
(författare)
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Production of mouse monoclonal antibodies that detect distinct neoantigenic epitopes on bound C3b and iC3b but not on the corresponding soluble fragments.
- 1987
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Ingår i: Molecular Immunology. - 0161-5890 .- 1872-9142. ; 24:5, s. 487-494
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Tidskriftsartikel (refereegranskat)abstract
- Polyclonal antibodies raised in rabbits against sodium dodecyl sulphate (SDS)-denatured and reduced human complement factor C3 have in recent studies been shown to lack any reactivity towards native C3 but to react with antigens distinctly expressed by SDS-denatured C3 (C3(D) antigens). These antigens are also neoantigens specific for physiologically bound C3 and appear to be involved in the interaction of C3 with other complement components. The present investigation deals with production of mouse monoclonal antibodies against C3(D) antigens. To accomplish this two different immunization and screening procedures employing C3 preparations of known C3(D) expression were tested. From each group 14 clones were randomly selected and the reactivity of these and of a control group of 14 additional monoclonal anti-human C3 antibody preparations raised against native soluble C3 and C3b, was investigated in ELISA and immunoblotting. The procedure which employed denatured reduced C3 as both immunogen as well as screening antigen was shown to be superior for obtaining anti-C3(D) antibodies. Altogether 16 clones producing antibodies against C3(D) antigens were found. All of them bound to the C3 alpha-chain, 14 to C3c and one to C3d, and eight monoclonal antibodies specific for neoantigens of C3(D) type on bound C3b and/or iC3b were obtained. The majority of these detected neoantigenic epitopes in the 25,000 N-terminal fragment of the C3 alpha-chain specifically exposed by bound iC3b, but one monoclonal antibody was specific for the 36,000 C-terminal alpha-chain fragment and for both bound C3b and iC3b.
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