Strategic use of an adenoviral vector for rapid and efficient ex vivo-generation of cytomegalovirus pp65-reactive cytolytic and helper T cells.

Cytomegalovirus (CMV) reactivation can cause severe complications for transplant patients. Such patients can be protected against CMV-associated diseases through reconstitution of donor-derived CMV-reactive cytolytic and helper T cells. We have developed a strategic protocol for efficient simultaneous generation of CMV-reactive CD8+ and CD4+ T cells ex vivo. The protocol uses peripheral blood lymphocytes (PBLs), antigen-modified mature dendritic cells (DCs) generated in only 3 d and an adenoviral vector encoding the CMV pp65 antigen (Adpp65) both as an endogenous and exogenous source of antigen. PBLs stimulated once with Adpp65-transduced DCs (endogenously expressed pp65) resulted in preferential activation and expansion of pp65-specific CD8+ T cells while PBLs stimulated with DCs pulsed with cell lysate from Adpp65-transduced autologous monocytes (exogenously expressed pp65) yielded pp65-specific CD4+ T cells. Stimulation with double-modified DCs efficiently activated and expanded cytolytic and helper T cells simultaneously. The frequency of T cells producing interferon-gamma in response to pp65 increased after one stimulation on average 9.6-fold to 4.3% for CD8+ T cells and 25.8-fold to 6.5% for CD4+ T cells. This implies that sufficient number of pp65-specific cytolytic and helper T cells for adoptive transfer may be obtained in only 2 weeks.