THE DETECTION AND CHARACTERIZATION OF A MEMBRANE-PROTEIN WITH FACTOR-B-LIKE ACTIVITY ON HUMAN LYMPHOID-CELLS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 44  (3) , 629-639
Abstract
Clones of B cells from patients with chronic lymphatic leukemia (CLL) and lymphoblastoid Raji cells were used to study Factor B-like activity. The surface of these cells was labeled with 125I by the lactoperoxidase technique and the cell membrane proteins solubilized with the detergent NP40. A single polypeptide chain of MW 103,000 was precipitated with F(ab'')2 anti-serum Factor B and not with a control antibody. This 103,000 MW protein was also found if Raji cells were biosynthetically labelled with [14C]-leucine. When the radiolabeled cells were incubated with cobra venom factor (CVF) and Factor D, 2 specific polypeptides were precipitated by F(ab'')2 anti-Factor B. The larger fragment forms a complex with CVF since it could be precipitated by anti-CVF. These events are similar to those involving serum Factor B and CVF.