Our immune system has specialized cellular soldiers—like T-cells and B-cells—ready to fight off bacterial invasions. However, non-immune cells aren’t entirely defenseless. Research published in Science in July 2021 found certain proteins literally have a detergent-like ability to wipe out bacteria like a grease stain. “This is a case where humans make their own antibiotic in the form of a protein that acts like a detergent,” says study author John MacMicking, an immunobiologist at Yale University, in a statement, “We can learn from that.” First, the team infected non-immune cells with Salmonella, a rod-shaped bacteria that affects the intestines. Then, they screened the cell’s genes for protective proteins and found a match: APOL3. This protein has parts drawn to water and other parts drawn to fats—just like laundry detergent. APOL3 attacks the greasy lipids lining the inner bacterial membrane with precision, never mistaking a human cell membrane for the invader. As resistance to antibiotics surges, an alternative option is needed. Pathogens may have their own proteins that interfere with APOL3’s counterattacks, but researchers could design a new antibiotic that targets those pesky proteins so APOL3 can do its thing. The research team also suggests designing small molecules that mimic APOL3’s actions using what’s called host-directed therapy, which creates a harsh environment for the pathogen instead of directly disarming it. But first, the scientists have to understand the breadth of infections controlled by APOL3 and other immune defense proteins. “That will incentivize the research effort in tackling important human bacterial, viral, and parasitic pathogens, especially if antibiotic resistance is already prevalent for those microbes and we need new drugs,” MacMicking says via email. “Inventions that mimic host protein activities are still relatively understudied,” MacMicking explains. “This could be fertile ground since our immune defenses are largely indifferent to whether pathogens are currently sensitive or resistant to known antibiotics.”