The Download: mysteries of the immunome, and how to choose a climate tech pioneer

How healthy am I? My immunome knows the score. Made up of 1.8 trillion cells and trillions more proteins, metabolites, mRNA, and other biomolecules, every person's immunome is different, and it is constantly changing. It's shaped by everything we have ever been exposed to physically and emotionally, and powerfully influences everything from our vulnerability to viruses and cancer to how well we age to whether we tolerate certain foods better than others. Yet as critical as the immunome is to each of us, it has remained largely beyond the reach of modern medicine. Now, thanks to a slew of new technologies, understanding this vital and mysterious system is within our grasp, paving the way for powerful new tools and tests to help us better assess, diagnose and treat diseases. On Monday, we published our 2025 edition of Climate Tech Companies to Watch .