Isolation and characterization of growth factor(s) from a human B-cell
lymphoma
CG Sahasrabuddhe, S Sekhsaria, L Yoshimura and RJ Ford
Department of Molecular Pathology, University of Texas System Cancer
Center, Houston 77030.
We demonstrate that human neoplastic B cells (Br cells) contain a
cytoplasmic protein of molecular mass 60 Kd that exhibits B-cell growth
factor (BCGF) activity on growth factor-dependent long-term human B cells
as well as on autochthonous tumor cells. This 60-Kd protein is recognized
by antibodies against a similar intracellular 60-Kd protein derived from
normal human lymphocytes. These results demonstrate that the two proteins
share epitope homology. Microculture bioassays indicate that neoplastic and
normal 60-Kd proteins are capable of driving neoplastic B cells through
S-phase. Western immunoblot analysis indicates that neoplastic B cells
secrete 60- as well as 14-Kd protein. Immunoaffinity-purified proteins
secreted by Br cells exhibit BCGF activity in anti-IgM or dextran
sulfate-preactivated human B cells. In addition, a double-antibody
immunofluorescence staining technique was used to demonstrate that Br cells
express cell surface receptors for BCGF molecule(s). These studies provide
support for the autocrine growth model for neoplastic human B cells and
suggest that the autocrine growth factor derived from such tumor cells is
similar if not identical to normal BCGF molecules.
Volume 73,
Issue 5,
pp. 1149-1156,
04/01/1989
Copyright © 1989 by The American Society of Hematology