Immunological studies on Crohn's disease. VIII. Diminished phagocytic activity in peripheral blood monocytes.

We have been examining superoxide production activity in patients with Crohn's disease and we noted an increase in this activity in peripheral whole blood and monocytes, determined by a luminol-dependent chemiluminescence. However, superoxide production and phagocytosis are different phenomena. To search for the "real" phagocytic capacity, we examined the phagocytic activity of peripheral blood monocytes and neutrophils in 20 Japanese patients with Crohn's disease, using automated laser flow cytometry. In contrast to the results obtained with the chemiluminescence assay, we found a decrease in the "real" phagocytic function in monocytes, yet there was no difference in the phagocytic ability in neutrophils. The phagocytic activity in patients with an active form of the disease was lower than that in patients with inactive form of the disease. These results provide pertinent information on the role of monocytes in Crohn's disease. The depressed phagocytic activity in monocytes from these patients may play some role in the pathogenesis of this disease.