Characterization of the lymphocyte membrane receptor for factor H (beta 1H-globulin) with an antibody to anti-factor H idiotype

J Exp Med. 1982 May 1;155(5):1400-11. doi: 10.1084/jem.155.5.1400.

Abstract

Antibody to the binding site (idiotype) of anti-factor H was shown to have specificity for both B lymphocyte membrane H receptors and C3b. Goat F(ab')(2) anti-human H was purified by absorption and elution from H agarose and used for rabbit immunization to produce anti-anti-H (aaH). After absorption with nonimmune goat IgG, (125)I-labeled aaH bound to B lymphocytes and to sheep erythrocytes coated with C3b (EC3b) but did not bind to T lymphocytes or to EC3d. All B cell- and C3b-specific activities of the aaH were removed and subsequently recovered by absorption and elution of the antibody from either C3-agarose or goat-anti-H-agarose. This indicated that the aaH probably recognized a single common antigenic structure that was shared by anti-H, C3b, and the membranes of B cells. Affinity-purified aaH resembled H in that it bound to B cells, blocked the uptake of H onto B cell H receptors, and triggered B cells to release endogenous factor I (C3b inactivator). In addition, aaH functioned with factor I as either a cofactor for cleavage of fluid-phase C3b or a potentiator for cleavage of bound C3b. This same spectrum of C3 binding functions could not be demonstrated with either sheep anti-C3b or rabbit-anti-C3c. Analysis by sodium dodecyl sulfate- polyacrylamide get electrophoresis of the [(3)H]leucine intrinsically labeled B cell proteins reactive with the purified aaH revealed proteins of 100,000 M(r) and 50,000 M(r) without reduction, and after complete reduction of disulfide bonds, a single protein band of 50,000 M(r). This same protein molecular weight profile was also demonstrated with labeled B cell proteins that were absorbed and eluted from H-agarose. Thus, aaH is apparently specific for both B cell H receptors and C3b. However, because parallel analysis of C3b confirmed its known 115,000- and 75,000-M(r) polypeptide chain structure, the H receptor is probably not C3b and shares only the structure of the H binding site with C3b.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Anti-Idiotypic / immunology
  • Antibody Specificity
  • Binding Sites, Antibody*
  • Binding, Competitive
  • Cell Line
  • Complement C3b / immunology
  • Complement C3b Inactivator Proteins / immunology
  • Complement C3b Inactivator Proteins / pharmacology*
  • Complement Factor H
  • Goats
  • Humans
  • Immunoglobulin Idiotypes / immunology*
  • Membrane Proteins
  • Molecular Weight
  • Rabbits
  • Receptors, Antigen, B-Cell / metabolism*

Substances

  • Antibodies, Anti-Idiotypic
  • Complement C3b Inactivator Proteins
  • Immunoglobulin Idiotypes
  • Membrane Proteins
  • Receptors, Antigen, B-Cell
  • complement factor H, human
  • Complement C3b
  • Complement Factor H