Red blood cells (RBCs) are emerging as an important regulator of cell function and survival. A small, but important body of literature has now demonstrated that the inclusion of RBCs in culture with other cell types can initiate changes in what proteins are secreted from those cells. We have conducted further research into this area and have discovered that RBCs are capable of both binding and releasing cytokines in response to their local environment. This investigation demonstrated that:
RBCs can bind and release proteins
The cytokine profile of RBCs can be manipulated by incubating RBCs in protein solutions
The cytokine profile of RBCs can be manipulated by incubating RBCs with a variety of human cells (including mesenchymal stem cells, lung cancer cells, and fibroblasts) to produce ‘primed’ RBCs and the cytokine profile of these RBCs varies according to the chosen cell line (Figure 1)
Cell-primed RBCs can subsequently alter the activity of T-cells (Figure 2)
Importantly, this study highlights that RBCs and their influence on the immune system can be altered. In disease, RBCs function differently and their control on immune cells is impaired. We have now also observed this by intentionally altering RBCs and their cytokine profile by exposing them to a lung cancer cell line (Figure 1). Following incubation with these cancer cells, these primed RBCs were loaded with a variety of pro-tumorigenic cytokines including bFGF, IL-8, and VEGF. Then, in the presence of these altered RBCs, T-cells were stimulated to proliferate to a greater degree (Figure 2), were no longer protected from stimulant-driven activation, and were driven to release a variety of cancer-related cytokines. In other experiments, RBCs incubated with a regenerative cell type (mesenchymal stem cells) produced a different, yet notable, cytokine profile indicating that this profile can be controlled.
Since RBCs are considered to be inert, they have been advocated as optimal biological carriers of antigens or drugs for cancer immunotherapy. Loading red blood cells with tumour specific antigens has been demonstrated to stimulate an extended T-cell response in mice. Our results demonstrate that unlike previous studies, without the addition of antigens or drugs, RBCs can be modified to become more immunogenic or to selectively activate populations of immune cells (Figure 2). Primed RBCs could be valuable in the future as personalised immunotherapies. Sangui Bio is now in the process of exploring the effect of RBC based immunotherapeutics in animal models of disease.