Prolonged Culture of Vaccine-Primed Lymphocytes Results in Decreased Antitumor Killing and Change in Cytokine Secretion

Abstract

Adoptive transfer of effector T cells has been used successfully to eliminate metastases in animal models. Because antitumor activity depends on the number of effector cells transferred, some human trials have used in vitro-repetitive activation and expansion techniques to increase cell number. We hypothesized that the prolonged culture period might contribute to the lack of human trial success by decreasing the potency of the effector T cells. Lymph nodes draining a progressively growing murine melanoma tumor transduced to secrete granulocyte/macrophage colonystimulating factor were harvested and activated in vitro with anti-CD3 monoclonal antibody followed by expansion in IL-2 for a total of 5 days in culture. Some lymphocytes were reactivated and further expanded for a total of 9 days in culture. In vivo activity of the effector T cells was measured by the reduction in lung metastases and is shown to be dose dependent. The prolonged culture period resulted in nearly 3-fold more T cells but at least 8-fold less antitumor activity. This was accompanied by decreased secretion of the proinflammatory cytokine, IFN-␥, and increased secretion of the anti-inflammatory cytokine, IL-10. Thus, although increased cell number is important to maximize the effectiveness of adoptive immunotherapy, some culture conditions may actually be counterproductive in that decreases in cell potency can outweigh the benefits of increased cell numbers. The T-cell cytokine secretion pattern predicts decreased effector cell function and may explain the decreased antitumor effect.

Long-Lived Antitumor CD8+ Lymphocytes for Adoptive Therapy Generated Using an Artificial Antigen-Presenting Cell

“…Consequently, the most fit antitumor CTL could be selected in vivo following adoptive transfer. In murine tumor models, prolonged culture of T cells decreases their effectiveness in eradicating tumors (44,45). This is also in agreement with recent observations in the adoptive transfer of ex vivo activated tumor-infiltrating lymphocytes (6,46).…”

Spontaneous Mammary Tumors Differ Widely in Their Inherent Sensitivity to Adoptively Transferred T Cells

“…The complete regressions we observed could be attributable to several factors, including the use of naive T cells, the use of a high-affinity T-cell epitope (SIINFEKL) linked to an essential oncogene, or the use of spontaneously arising tumors rather than implanted cell lines. Previous studies have assessed whether naive or activated CD8 + T cells have greater antitumor activity (33,34). In general, the evidence favors the use of naive T cells, which have a greater proliferative and tumor killing capacity than previously activated T cells.…”

A safeguard eliminates T cell receptor gene-modified autoreactive T cells after adoptive transfer

“…Hence, peripheral blood lymphocytes (PBLs) will have to be independently transduced with a TCR and a second gene-encoding vector, increasing the number of retroviral integrations into the host cell genome and, thus, the risk of insertional mutagenesis (25). Also, the purification and analysis steps needed to ensure that all TCR-redirected cells express the safety modality will prolong the in vitro culture time and decrease their functionality (26).…”