An estimated 1.3 million people in the United States suffer from rheumatoid arthritis. The causes behind this chronic disease — which can exhibit itself as pain, swelling, stiffness, deformation, and loss of function in the joints — have eluded scientists for centuries. A new study by UNC researchers offers tantalizing glimmers about the roles of a gene called CCR2, an immune system cell called Th17 cell, and a missing monocyte.