Serial killing of tumor cells by cytotoxic T cells redirected with a CD19-/CD3-bispecific single-chain antibody construct.
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.
Hoffmann
Patrick
P
Micromet AG, Munich, Germany.
Hofmeister
Robert
R
Brischwein
Klaus
K
Brandl
Christian
C
Crommer
Sandrine
S
Bargou
Ralf
R
Itin
Christian
C
Prang
Nadja
N
Baeuerle
Patrick A
PA
D018033:Antibodies, Bispecific / Q000737:chemistry; D018941:Antigens, CD19 / Q000096:biosynthesis*; D001402:B-Lymphocytes / Q000276:immunology; D017252:CD3 Complex / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003602:Cytotoxicity, Immunologic; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry*; D007167:Immunotherapy / Q000379:methods*; D007376:Interleukin-2 / Q000378:metabolism; D007700:Kinetics; D008213:Lymphocyte Activation; D018715:Microscopy, Video; D009369:Neoplasms / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D013997:Time Factors
D018033:Antibodies, Bispecific; D018941:Antigens, CD19; D017252:CD3 Complex; D007128:Immunoglobulin Fragments; D007376:Interleukin-2