‘Invisible’ Deep-Sea Bacteria Cause Researchers to Rethink Human Immune Systems Image: Schmidt Ocean Institute Researchers have found microbes in the deep sea that are completely invisible to the human immune system, a somewhat unnerving discovery that suggests our bodies’ seemingly universal ability to recognize bacteria isn’t so all-inclusive. Advertisement The interdisciplinary team’s research was published last week in the journal Science Immunology. Their fundamental conclusion is that the way our mammalian immune systems sniff out trouble—the rules and patterns we follow to protect ourselves—may be defined locally rather than globally, a finding that goes against a long-held belief in immunology. These marine microbes have never been in contact with mammalian life before, not even marine mammals, according to the researchers.