Role of perforin, granzymes and the proliferative state of the target cells in apoptosis and necrosis mediated by bispecific-antibody-activated cytotoxic T cells

Abstract

Bispecific monoclonal antibodies (bi-mAb), directed against a tumor-associated antigen and the CD3 or CD28 antigen on T lymphocytes, induce activation of resting T lymphocytes and target-specific tumor cell lysis. We now show that both necrosis and apoptosis contribute to T-cell-mediated tumor cell destruction. Even though T cells up-regulate FAS/APO-1 expression upon bi-mAb stimulation, FAS/APO-1-mediated apoptosis does not contribute to bi-mAb-mediated destruction of Hodgkin's cells. CD8+ lymphocytes were the most potent effectors of bi-mAb-mediated cytotoxicity and had the highest levels of mRNA coding for perforin and granzyme A and B. Ca2+-complexing agents, which abrogate perforin activity, led to decreased levels of necrosis, while inhibition of granzyme activity in effector or target cells had a similar effect on apoptosis. Granzyme-mediated apoptosis critically dependent on the proliferative state of the target cells, while perforin-induced necrosis was not cell-cycle-dependent. Our results underline the importance of the expression levels of perforin and granzymes in the effector T cells and of the proliferative state of the target cells in bi-mAb-mediated apoptosis and necrosis of tumor cells.

Taxanes Synergize with the Bispecific Antibody MDXH447 to Enhance Antibody-Dependent Cell-Mediated Cytotoxicity

“…This mechanism of target cell death may be especially relevant in monocytemediated ADCC 17,18 . Several investigators showed that lysis of target cells by both T-cells 19 and monocytes 20 via ADCC is associated with activation of apoptotic pathways. Paclitaxel was shown to impact on Raf-dependent tumor apoptosis that is also a signaling pathway modulated by ADCC 21 .…”

Murine hypodense eosinophils induce tumour cell apoptosis by a granzyme B-dependent mechanism

“…Intracellular aprotinin inhibits cytotoxicity by CTL, perforin and granzyme A-transfected mast cells [20], and antibody-activated T cells [35], and inhibits enzymatic activity of puri®ed granzyme A and B in vitro [36]. Although aprotinin also inhibits other serine proteases [21], the reduction in cytotoxicity with a competitive substrate for granzyme B corroborates a role for granzyme B in the killing mechanism.…”

Exogenous IL-10 overexpression reduces perforin production by activated allogenic CD8+cells and prolongs cardiac allograft survival

“…Two proteins, perforin and granzyme B, are integral components of the lytic machinery of cytotoxic cells (19), and cytotoxic cells are often present in allografts that are undergoing acute rejection (25). In addition, inhibition of perforin expression by antisense perforin oligonucleotides in T lymphocytes activated in vitro results in a proportional decrease of CTL cytotoxicity in mice (1).…”