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Anaphylatoxin formation by contact activation of plasma. II. Implication of properdin and an unknown plasma factor in activation by zymosan
Author(s) -
Brade V.,
Vogt W.
Publication year - 1971
Publication title -
european journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 201
eISSN - 1521-4141
pISSN - 0014-2980
DOI - 10.1002/eji.1830010416
Subject(s) - zymosan , properdin , anaphylatoxin , complement system , alternative complement pathway , incubation , opsonin , chemistry , biochemistry , immunology , biology , in vitro , antibody
Abstract During incubation with human serum at 37°C zymosan is coated with factors which liberate anaphylatoxin (AT) from its precursor, anaphylatoxinogen. Serum free of properdin (RP), prepared by previous absorption with zymosan at 17°C, does not generate an AT‐forming system when subsequently incubated with fresh zymosan, at 37°C. Only after addition of properdin to RP does the mixture fix an effective system onto zymosan. Serum pretreated with zymosan at 37°C (zymosan‐R3) is unable to subsequently coat fresh zymosan with an AT‐forming system even when properdin is added. It is concluded that in addition to properdin and possibly complement factors C1, C4 and C2 an unknown serum factor (UF) is essential for the generation of AT forming activity on zymosan. UF is present in RP and in cobra venom‐treated serum (cobra‐R3) but absent from zymosan‐R3. It is subject to decay once fixed to zymosan. Decayed zymosan complexes can be regenerated by incubating them with an appropriate source of UF, e. g. RP or cobra‐R3, whereas reagents containing only early complement components and/or properdin d o not reactivate them. The results indicate that AT formation in serum by zymosan and probably other polysaccharides proceeds by a pathway different from the classical complement reaction.