Peripheral granulocytes of patients with Crohn's disease express increased numbers of functional IgG Fc receptor I.

Activated phagocytes are involved in the pathogenesis of Crohn's disease (CD). To clarify the activation of polymorphonuclear leukocytes (PMN) from CD patients in relationship with the clinical status, we investigated not only the expression of Fc receptor for IgG (huFc gamma R) but also the ability of the PMN to produce free oxygen radicals on stimulation of these receptors by using chemiluminescent techniques. The PMN obtained from the patients with active disease showed an enhanced chemiluminescence (CL) in response to huFc gamma RI stimulation, and an increased expression of huFc gamma RI. Moreover, PMN with huFc gamma RI were recognized in the colonic inflammatory lesions. After a successful treatment, however, we could hardly detect both the CL production and the expression of huFc gamma RI. Thus, it is suggested that the measurement of CL production through huFc gamma RI and the evaluation of the expression of huFc gamma RI are useful to evaluate the clinical status of the CD patients in a more accurate manner. The involvement of huFc gamma RI positive PMN in tissue destruction has been discussed.