Tissues are continually exposed to reactive oxygen species (ROS) that are produced in tissues from metabolism processes or the inflammatory response of leukocytes or macrophages. These ROS can cause damage to various cellular components. Dinitrophenylhydrazine (DNPH) will react with free carbonyl groups on proteins, leading to adduction of the dinitrophenyl (DNP) group to the carbonyl group. Using an antibody to DNP, it is possible to visualize and localize the sites of oxidative damage by immunodetection of DNP adduction resulting from reaction of the tissue with DNPH.