When one thinks of the cells of the immune system, they immediately get the role of the bodies marines. But new research has shown that there is more than meets the eye. Researchers from Oregon State noticed that mice lacking antibody producing B cells have unusual digestive systems. They noticed that the mice had a troublesome time absorbing fat from their diet which leads to malnutrition. From there the fact that B cells make immunoglobulin A (IgA) must contribute to fat uptake. IgA is found in tears, saliva, milk, mucus, and the lining of the intestines. When a closer look is taken on the intestines, one will notice that the intestines are lines with epithelial cells. Now epithelial cells have two jobs, self defense and metabolism (which includes fat uptake). IgA (which is produced by B cells), is triggered by an unknown, a signal will be sent from the gut microbes to the epithelial cells. From there commands will be made on what to do next. A variety of things could happen. 1) Devote more resources to protecting themselves. 2) Make antimicrobial compounds. Or 3) continue absorbing fat and other nutrients from food. Whatever the outcome is, it would not occur easily without B cells. So be thankful that your bodies “marines” not only have training in combat, but in many other areas as well, because let's face it, you would be malnourished without them.