Analysis of CD20-dependent cellular cytotoxicity by G-CSF-stimulated neutrophils

Leukemia. 2002 Apr;16(4):693-9. doi: 10.1038/sj.leu.2402424.


Rituximab, a chimeric CD20 monoclonal antibody (mAb), is widely used in the treatment of patients with low-grade non-Hodgkin's lymphoma. Possible anti-tumour mechanisms involve complement-mediated lysis and/or antibody-dependent cellular cytotoxicity (ADCC). Because G-CSF greatly enhances the cytotoxicity of neutrophils (PMN) in ADCC, the clinical efficacy of rituximab might be enhanced by the addition of G-CSF. Therefore, we investigated the neutrophil-mediated CD20-dependent cellular cytotoxicity in B cell lines. In contrast to previous studies by others, we found that G-CSF-primed PMN are capable of functioning as effector cells in CD20-dependent cellular cytotoxicity. However, HLA class II mAbs were far more effective. The differences between HLA class II- and CD20-mediated PMN-ADCC were not due to: (1) the use of chimeric (hIgG1) mAbs vs mIgG2a mAbs; (2) HLA class II-induced apoptosis as an 'ADCC-sensitising' mechanism; (3) CD20-induced inhibition of ADCC; (4) inferior membrane mobility of CD20. Analysis of Fcgammareceptor (FcgammaR) involvement showed that although CD20-induced ADCC was mediated mainly via FcgammaRI, for optimal lysis FcgammaRI and FcgammaRII were both required. In contrast, in HLA class II-dependent ADCC both FcgammaRI and II were capable of independently inducing maximum lysis. The mechanism underlying these differences in FcgammaR-binding and activation remains to be elucidated.

MeSH terms

  • Antibodies, Bispecific / immunology
  • Antibodies, Monoclonal / pharmacology
  • Antibodies, Monoclonal, Murine-Derived
  • Antibody-Dependent Cell Cytotoxicity / immunology*
  • Antigens, CD20 / immunology*
  • Apoptosis / drug effects
  • B-Lymphocytes / immunology
  • Granulocyte Colony-Stimulating Factor / pharmacology*
  • Histocompatibility Antigens Class II / immunology
  • Humans
  • Immunoglobulin Fc Fragments / immunology
  • Monocytes / immunology
  • Neutrophil Activation / drug effects
  • Neutrophils / immunology*
  • Rituximab
  • Tumor Cells, Cultured / cytology
  • Tumor Cells, Cultured / drug effects
  • Tumor Cells, Cultured / immunology


  • Antibodies, Bispecific
  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Murine-Derived
  • Antigens, CD20
  • Histocompatibility Antigens Class II
  • Immunoglobulin Fc Fragments
  • Granulocyte Colony-Stimulating Factor
  • Rituximab