Abnormalities of some phagocyte membrane receptors during nosocomial infections

The frequent and severe nosocomial infections in ICU patients suggest that these patients are immunodeficient. We studied the phagocytic activity of granulocytes and monocytes isolated from the blood of 32 ICU patients with nosocomial pneumonia (19 male, 13 female; age 41 +/- 4 yr). Cells were tested in standard medium and in the presence of patients' serum. Blood granulocytes and monocytes were purified and separately exposed to opsonized zymosan (to test C3 receptor function), immunoglobulin-coated erythrocytes (to test Fc receptor function), and glutaraldehyde-treated erythrocytes (to test nonspecific binding structures). Phagocytosis and superoxide anion production were measured. Granulocytes of patients exhibited a substantial decrease of zymosan ingestion (p less than .05), whereas phagocytosis of other particles was normal. Monocytes from the patients displayed an unselective overall decrease of phagocytic ability for the three particle types (p less than .05). Patients' sera were at least as efficient as a pool of normal sera in opsonizing zymosan. Further, no phagocytic inhibitor was found in the tested patients. In conclusion, we point out a deficiency of membrane receptors of neutrophils and monocytes in ICU patients with nosocomial infection.