Serial killing of tumor cells by cytotoxic T cells redirected with a CD19-/CD3-bispecific single-chain antibody construct

Int J Cancer. 2005 May 20;115(1):98-104. doi: 10.1002/ijc.20908.


Certain bispecific antibodies exhibit an extraordinary potency and efficacy for target cell lysis by eliciting a polyclonal T-cell response. One example is a CD19-/CD3-bispecific single-chain antibody construct (bscCD19xCD3), which at femtomolar concentrations can redirect cytotoxic T cells to eliminate human B lymphocytes, B lymphoma cell lines and patient-derived malignant B cells. Here we have further explored the basis for this high potency. Using video-assisted microscopy, bscCD19xCD3 was found to alter the motility and activity of T cells from a scanning to a killing mode. Individual T cells could eliminate multiple target cells within a 9 hr time period, resulting in nuclear fragmentation and membrane blebbing of target cells. Complete target cell elimination was observed within 24 hr at effector-to-target cell ratios as low as 1:5. Under optimal conditions, cell killing started within minutes after addition of bscCD19xCD3, suggesting that the rate of serial killing was mostly determined by T-cell movement and target cell scanning and lysis. At all times, T cells remained highly motile, and no clusters of T and target cells were induced by the bispecific antibody. Bystanding target-negative cells were not detectably affected. Repeated target cell lysis by bscCD19xCD3-activated T cells increased the proportion of CD19/CD3 double-positive T cells, which was most likely a consequence of transfer of CD19 from B to T cells during cytolytic synapse formation. To our knowledge, this is the first study showing that a bispecific antibody can sustain multiple rounds of target cell lysis by T cells.

MeSH terms

  • Antibodies, Bispecific / chemistry
  • Antigens, CD19 / biosynthesis*
  • B-Lymphocytes / immunology
  • CD3 Complex / biosynthesis*
  • Cell Line, Tumor
  • Cell Membrane / metabolism
  • Cell Nucleus / metabolism
  • Cytotoxicity, Immunologic
  • Dose-Response Relationship, Drug
  • Flow Cytometry
  • Humans
  • Immunoglobulin Fragments / chemistry*
  • Immunotherapy / methods*
  • Interleukin-2 / metabolism
  • Kinetics
  • Lymphocyte Activation
  • Microscopy, Video
  • Neoplasms / immunology*
  • T-Lymphocytes / immunology
  • T-Lymphocytes, Cytotoxic / immunology*
  • Time Factors


  • Antibodies, Bispecific
  • Antigens, CD19
  • CD3 Complex
  • Immunoglobulin Fragments
  • Interleukin-2