Coffee doesn't just wake you up — a biological pathway sheds light on its health effects | Hacker News

Caffeine may affect immune cells through two dose-dependent pathways: blocking adenosine A2A receptors and inhibiting phosphodiesterase.

These mechanisms can push immunity in opposite directions—one may stimulate immune activity, while the other may suppress it.

The discussion links caffeine’s immune signaling effects to possible relevance in cancer biology and the tumor microenvironment.

However, the real-world impact of caffeine in tumors has not yet been proven.