Extremely potent, rapid and costimulation-independent cytotoxic T-cell response against lymphoma cells catalyzed by a single-chain bispecific antibody

Int J Cancer. 2002 Aug 20;100(6):690-7. doi: 10.1002/ijc.10557.


A recent study reported on an anti-CD19/anti-CD3 single-chain bispecific antibody (bscCD19xCD3) exhibiting high activity against human B lymphoma cell lines (Löffler et al., Blood 2000;95:2098-103). In the present study, we have explored in detail the in vitro efficacy, T-cell donor variability, binding characteristics, specificity, kinetics and interleukin-2 (IL-2) dependence of bscCD19xCD3. We found that a majority of human donor T cells tested (n = 86) gave half-maximal B-lymphoma cell lysis (ED(50)) within a range of 10-50 pg/ml bscCD19xCD3, corresponding to sub-picomolar concentrations of the bispecific antibody. Under identical experimental conditions, the anti-CD20 monoclonal antibody rituximab had an at least 100,000-fold lower in vitro efficacy. The extreme potency of bscCD19xCD3 was in sharp contrast to the relatively low affinity of the anti-CD3 and anti-CD19 single-chain Fv portions in K(D) ranges of 10(-7) and 10(-9) M, respectively. Cell lysis by bscCD19xCD3 was predominantly mediated by the population of CD8/CD45RO-positive T cells. Both immortalized CD4- and CD8-positive human T-cell clones were highly active effector cells as well. Cell lysis by bscCD19xCD3 was rapid and specific. The respective parental monoclonal antibodies inhibited cell lysis and CD19-negative cells were not harmed by T cells in the presence of high amounts of bscCD19xCD3. The potent T-cell stimulus IL-2 could not markedly augment the activity of bscCD19xCD3-stimulated T cells. In conclusion, bscCD19xCD3 could redirect unstimulated cytotoxic T cells against CD19-positive cells in an unexpectedly potent, rapid and specific fashion.

MeSH terms

  • Animals
  • Antibodies, Bispecific / metabolism*
  • Antibodies, Monoclonal / therapeutic use
  • Antibodies, Monoclonal, Murine-Derived
  • Antigens, CD19 / metabolism*
  • CD3 Complex / metabolism*
  • CHO Cells
  • Cell Separation
  • Cricetinae
  • Dose-Response Relationship, Immunologic
  • Flow Cytometry
  • Humans
  • Interleukin-2 / metabolism
  • Kinetics
  • Lymphocyte Activation
  • Lymphoma / metabolism*
  • Mice
  • Rituximab
  • T-Lymphocytes, Cytotoxic / metabolism*
  • Time Factors
  • Tumor Cells, Cultured


  • Antibodies, Bispecific
  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Murine-Derived
  • Antigens, CD19
  • CD3 Complex
  • Interleukin-2
  • Rituximab