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Complement‐Fixing Properties of Human IgA Antibodies Alternative Pathway Complement Activation by Plastic‐Bound, But Not Specific Antigen‐Bound, IgA
Author(s) -
RUSSELL M. W.,
MANSA B.
Publication year - 1989
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1989.tb01199.x
Subject(s) - antibody , complement system , antigen , polyclonal antibodies , classical complement pathway , alternative complement pathway , immunology , monoclonal antibody , biology , chemistry
The complement‐fixing properties of human IgA antibodies bound lo specific antigen, or coated directly on plastic surfaces, were examined in comparison with those of IgG antibodies. Use was made of antigen‐binding (anti‐staphylococcal α‐toxin) IgA and IgG monoclonal antibodies and normal polyclonal IgA and IgG, purified >99.9% by avoidance of denaturing processes. Complement‐fixation ELISA was used, with a high density of biotin‐conjugated staphylococcal α‐toxin bound to avidin‐coated plates for the efficient capture of antibodies, and conditions were adjusted for the assessment of classical and alternative pathways of complement activation. Although IgA coated directly on plastic surfaces activated the alternative complement pathway in a dose‐dependent manner, IgA antibodies bound to antigen failed to fix complement by either classical or alternative pathways. In contrast, IgG antibodies, either bound to antigen or coated directly on plastic, activated complement mainly by the classical pathway. It was concluded that the complexation of IgA antibodies with antigen is insufficient to elicit complement actuation: rather a degree of denaturation seems to play a part in the expression of alternative complement pathway‐activating properties by IgA.