Simulated microgravity-mediated reversion of murine lymphoma immune evasion.

No human has returned to the moon since the end of the Apollo program 47 years ago, however, new missions are planned for an orbital outpost. Space radiation and the potential for cancer remain as important issues to the future of human space exploration. While improved shield technologies and protective biologicals are under development, little is known concerning the interaction between cancer cells and host immunity in microgravity.

Prolonged exposure to simulated microgravity diminishes dendritic cell immunogenicity.

Immune dysfunction due to microgravity remains a hurdle in the next step of human space exploration. Dendritic cells (DC) represent a critical component of immunity, given their role in the detection of invaders and the subsequent task of activating T cells to respond and eliminate the threat. Upon encounter with microbes, DC undergo a process of maturation, whereby the cells upregulate the expression of surface proteins and secrete cytokines, both required for the optimal activation of CD4 and CD8 T cells.

T cell resistance to activation by dendritic cells requires long-term culture in simulated microgravity.

Immune impairment mediated by microgravity threatens the success of space exploration requiring long-duration spaceflight. The cells of most concern, T lymphocytes, coordinate the host response against microbial and cancerous challenges leading to elimination and long-term protection. T cells are activated upon recognition of specific microbial peptides bound on the surface of antigen presenting cells, such as dendritic cells (DC).