A cohort study is performed involving healthy adult men and women born 20 years ago. They are followed to assess the development of atherosclerotic cardiovascular diseases. Multiple laboratory tests are performed yearly during this study. An increase in which of the following is most likely to indicate the greatest relative risk for the development of one of these diseases?

CRP is an acute-phase reactant that increases in response to inflammation. It causes endothelial cell activation, promotes thrombosis, and increases leukocyte adhesiveness in developing atheroma. Because atherogenesis is partly an inflammatory process, CRP is an independent predictor of cardiovascular risk. PR3 is one type of anti-neutrophil cytoplasmic autoantibody (ANCA) associated with some vasculitides such as microscopic polyangiitis. Cryoglobulins may be found with some forms of immune complex-mediated vasculitis. The ESR ("sed rate") is a nonspecific indicator of inflammation and therefore the internist's least favorite test; the ESR is best known to be markedly elevated with giant cell arteritis. Though platelets play a role in atheroma formation, the actual number of platelets is not a predictor of atherogenesis.