B cells are the immune cells responsible for creating antibodies, and most B cells, known as B2 cells, produce antibodies in response to a pathogen or a vaccine, providing defense and immunity against infections. But a small subset of long-lived B cells, known as B1 cells, are quite different from their short-lived cousins, the B2 cells. Instead of producing antibodies in response to invaders, they spontaneously make antibodies that perform vital housekeeping functions, such as removing waste like oxidized LDL cholesterol from the blood.