Purified Anti-Rat Crry monoclonal antibody (Clone: 5I2) is a rat-specific membrane complement regulator that can inhibit both antibody-induced classical pathway and alternative pathway complement activation. Crry plays a more dominant role than DAF in regulating the alternative pathway of complement and in preventing spontaneous complement damage of rat erythrocytes, whereas DAF and Crry are both expressed and are equally effective in preventing antibody-induced runaway complement activation on rat erythrocytes.