Targeting CMV Infection Post-Allogeneic Stem Cell Transplantation With Anti-CD3 (OKT3) × Anti-CMV (Cytogam®) Bispecific Antibody Armed Activated T Cells
Year: 2011
Type: article
Abstract: Reactivation of cytomegalovirus (CMV) is a major barrier to the success of organ and allogeneic stem cell transplantation (alloSCT). Current management strategies are suboptimal and associated with significant adverse effects. Patients undergoing alloSCT are profoundly immunocompromised and do not respond to vaccination with CMV antigens. Immunotherapy (IT) with CMV specific donor-derived cytotoxic T lymphocytes (CTL) is effective after alloSCT, but is expensive, labor intensive, and difficult to replicate. Non-toxic strategies are needed to improve outcomes. In earlier studies, we showed that ex vivo expanded activated T cells (ATC) armed with anti-CD3 × anti-Her2/neu bispecific antibody (Her2Bi) exhibit high levels of specific cytotoxicity directed at breast cancer cell lines. Using this strategy, we tested ATC armed with anti-CD3 (OKT3) × anti-CMV (Cytogam®) bispecific antibodies (CMVBi) to target and lyse CMV-infected fibroblasts. Normal donor ATC were generated and armed with CMVBi. Specific cytotoxicity was tested by 51Cr release using CMV-infected or uninfected human fibroblasts. CMVBi alone, CMVBi-armed ATC (aATC), and ATC alone were tested for their ability to kill. ATC were armed with 0.001 to 500 ng of CMVBi/106ATC at effector:target (E:T) from 3.125:1 to 25:1. IFNγ EliSpot was used to assess IFNγ secreting cells in ATC and aATC after exposure to CMV-infected and uninfected fibroblasts. ATC armed with CMVBi as little as 0.001 ng/106 ATC was significantly more cytotoxic than unarmed ATC. There was higher cytotoxicity mediated by aATC as the multiplicity of infection (MOI) increased in target cells. At all E:T, CMVBi arming at a dose of 50 ng/106 ATC exhibited dramatically higher lysis of CMV-infected targets (MOI 1) than that exhibited by ATC alone. Cytotoxicity mediated by unarmed and armed ATC was background in uninfected targets. Immunofluorescent studies showed that aATC aggregated around GFP fluorescence-marked CMV-infected fibroblasts. Cytokine secretion analyzed by IFNγ EliSpot confirmed immune responses. The lack of MHC restriction in the mediation of cytotoxicity, polyclonal targeting of multiple CMV antigens and the simplicity of expanding donor T cells makes it easy to adapt this effective strategy against CMV infection post alloSCT.
Language: English
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $3,650
OpenAlex ID: W2072420381