Isolation of lymphocyte membrane complement receptor type two (the C3d receptor) and preparation of receptor-specific antibody

Proc Natl Acad Sci U S A. 1981 Mar;78(3):1828-32. doi: 10.1073/pnas.78.3.1828.


A glycoprotein binding complement component C3d was isolated from media used for culture of Raji human lymphoblastoid cells. Analysis by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and gas/liquid chromatography indicated that the C3d-binding glycoprotein consisted of a single polypeptide chain with extensive intrachain disulfide bonds, a molecular weight of 72,000, and several different bound carbohydrates. Several lines of evidence indicated that this medium-derived C3d-binding protein originated from membrane complement receptor type two (CR2, the C3d receptor), presumably shed during membrane turnover. The C3d-binding protein bound to sheep erythrocytes coated with C3d (EC3d) but not to sheep erythrocytes coated with C3b (EC3b). Antisera, prepared by immunization with the purified C3d-binding glycoprotein, inhibited lymphocyte rosette formation with EC3d but not with EC3b. Analysis by sodium dodecyl sulfate gel electrophoresis of the radiolabeled and solubilized lymphocyte antigens reactive with the anti-C3d-binding protein sera revealed a single-chain cell-surface protein of molecular weight 72,000 that was apparently identical to the isolated C3d-binding protein. Parallel assay of lymphocytes for Cr2 by direct immunofluorescence with F(ab')2 anti-C3d-binding protein (anti-CR2) and rosette formation with EC3d indicated that both assays had the same specificity and nearly the same sensitivity. With both systems CR2 expression was limited to B cells, and was undetectable on T cells, monocytes, or neutrophils.

Publication types

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

MeSH terms

  • Animals
  • Antibodies
  • Antigen-Antibody Complex
  • B-Lymphocytes / immunology*
  • Cell Line
  • Cell Membrane / immunology
  • Humans
  • Leukemia, Lymphoid / immunology
  • Molecular Weight
  • Rabbits / immunology
  • Receptors, Complement / immunology*
  • Receptors, Complement 3d
  • Rosette Formation


  • Antibodies
  • Antigen-Antibody Complex
  • Receptors, Complement
  • Receptors, Complement 3d