Isolation and characterization of growth factor(s) from a human B-cell lymphoma.
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.
Sahasrabuddhe
C G
CG
Department of Molecular Pathology, University of Texas System Cancer Center, Houston 77030.
Sekhsaria
S
S
Yoshimura
L
L
Ford
R J
RJ
D000328:Adult; D000906:Antibodies; D001402:B-Lymphocytes / Q000032:analysis* / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D006801:Humans; D007164:Immunosorbents; D015847:Interleukin-4; D007378:Interleukins / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D008228:Lymphoma, Non-Hodgkin / Q000032:analysis* / Q000378:metabolism; D008297:Male; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen / Q000032:analysis
D000906:Antibodies; D007164:Immunosorbents; D007378:Interleukins; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen; D015847:Interleukin-4