Provided are a therapeutic agent, a treatment method and a test method for diseases associated with the activation of neutrophils. More specifically, the present invention relates to a neutrophil activation regulator comprising a histidine-rich glycoprotein (HRG) as an active ingredient, and provides: a therapeutic agent for diseases associated with the activation of neutrophils, which comprises the neutrophil activation regulator； a method for treating a disease associated with the activation of neutrophils； and a method for testing for diseases associated with the activation of neutrophils. A neutrophil activation regulator comprising a HRG as an active ingredient. The present invention also provides: a neutrophil-vascular endothelial cell interaction inhibitor comprising the HRG according to the present invention as an active ingredient； and a method for treating diseases associated with the activation of neutrophils and/or inflammatory diseases accompanied by the activation of neutrophils. The present invention further provides a method for testing for inflammatory diseases accompanied by the activation of neutrophils by measuring a HRG level in blood.L'invention concerne un agent thérapeutique, une méthode de traitement et un procédé d'essai pour des maladies associées à l'activation de granulocytes neutrophiles. Plus particulièrement, la présente invention concerne un régulateur de l'activation des granulocytes neutrophiles comprenant une glycoprotéine riche en histidine (HRG) en tant que principe actif, et fournit : un agent thérapeutique pour des maladies associées à l'activation de granulocytes neutrophiles, lequel comprend le régulateur d'activation de granulocytes neutrophiles ； une méthode de traitement d'une maladie associée à l'activation de granulocytes neutrophiles ； et un procédé d'essai pour des maladies associées à l'activation de granulocytes neutrophiles. L'invention concerne un régulateur d'activation des granulocytes neutrophiles comprenant un
