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A monoclonal antibody to C1q which appears to interact with C½C½s 2 ‐binding site
Author(s) -
Hsiung Li-min,
Dodds Alister W.,
Mason Donald W.,
Reid Kenneth B.M.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80789-0
Subject(s) - chemistry , antibody , monoclonal antibody , complement c1q , dimer , binding site , pepsin , microbiology and biotechnology , biophysics , biochemistry , enzyme , complement system , biology , immunology , organic chemistry
A monoclonal antibody (SB‐4) to human C1q was prepared. The equilibrium constant of the antibody for C1q was found to be greater than 10 10 M −1 . It has been shown that the antibody binds to the A‐B chain dimer, probably via the B chain of C1q. Pepsin digestion of C1q at pH 4.5, which fragments the globular regions but leaves the collagenous region intact, allowed the demonstration that the antigenic site is located in the collagenous region of the molecule. The effect of the antibody on haemolytic activity has shown that it is capable of inhibiting the formation of EAC1 cells from EAC1q cells plus C1r and C1s but is incapable of inhibiting the C1 activity of preformed EAC1 cells. This indicates that the binding of the antibody to the collagenous portion of the B chain of C1q probably prevents interaction between C1q and the C1r 2 ‐C1s 2 complex.