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Intestinal Glycoprotein Activates the Alternative Complement Pathway by Reacting with Factor H
Author(s) -
WINSNES R.,
LACHMANN P. J.
Publication year - 1982
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.1365-3083.1982.tb00661.x
Subject(s) - glycoprotein , alternative complement pathway , complement factor b , chemistry , antiserum , orosomucoid , complement system , albumin , biochemistry , classical complement pathway , immunoelectrophoresis , serum albumin , properdin , blood proteins , antibody , microbiology and biotechnology , biology , immunology
Previous observations indicating complement activation via the alternative pathway of chelaled human serum by a rat intestinal glycoprotein fraction were substantiated by using C2‐deficient serum. Some inactivation of C6 by the glycoprotein was observed both in normal and C2‐deficient serum. As estimated by conglutination, the glycoprotein largely abolished the ability of serum to convert EAC3b to EA3Cbi, indicating inhibition of the control factors H (β1H globulin) and I (C3bINA), or inhibition of C3b deposition on the cells. The glycoprotein caused no change in the electrophoretic mobility of factors H or I. By immunoelectrophoresis the glycoprotein interfered with the precipitation line of plasminogen and β‐lipoprotetn and some other serum proteins. The absence of plasminogen or β‐lipoprotein in serum seemed unimportant for the C3 conversion by the glycoprotein. Factor H was retained when heal‐inactivated serum, heat‐inactivated serum depleted of 99% albumin or 85% IgG, or heat‐inactivated hypogammaglobulinaemic serum was eluted through a column of the intestinal glycoprotein coupled to epoxy‐activated Sepharose 6B. Presence of EDTA abolished factor H retention. Factor H from methylamine‐treated serum was also adsorbed to the glycoprotein. When serum depleted at 5°C of 31% of the factor H content was healed, the alternative pathway was activated spontaneously. Addition of some of the previously removed factor H reduced the O and factor B conversion rate.