STUDY OF SOME PHAGOCYTE MEMBRANE-RECEPTORS IN PATIENTS RECEIVING INTRAVENOUS POLYVALENT IMMUNOGLOBULINS AS ADJUNCT TREATMENT FOR NOSOCOMIALPNEUMONIA

Purpose: Phagocytosis is a major mechanism of defense against bacteria l infections. The ingestion of bacteria by phagocytes involves a varie ty of cell membrane recognition structures and, among them, immunoglob ulin receptors. The aim of this study was to test the phagocytic activ ity of granulocytes and monocytes of intensive care unit (ICU) patient s, and to evaluate the effects of intravenous polyvalent immunoglobuli ns (IVIG) used as adjunct treatment of nosocomial pneumonia on some ph agocyte membrane receptors of these patients. Materials and Methods: T he phagocytic activity of granulocytes and monocytes of 41 mechanicall y ventilated patients with nosocomial bacterial pneumonia was studied during the acute phase of infection. These ICU patients were compared with 21 hospitalized, noninfected volunteer patients hospitalized in a medical ward. Peripheral blood granulocytes and monocytes were studie d. Of the 41 ICU patients, after randomization, 21 received IVIG at a dose of 1 g/kg for 3 days. The 41 ICU patients were compared with the 21 non-ICU, noninfected hospitalized controls. The 21 ICU patients who received 3 days of IVIG were also compared with the 20 ICU patients n ot receiving IVIG. Cells were tested in standard immunoglobulin-free m edium (fetal calf serum) and in the presence of patients' serum, Blood granulocytes and monocytes were purified and separately exposed to th ree types of particles: antibody-coated erythrocytes (to test immunogl obulin receptors), opsonized zymosan (to test C3 receptors), and gluta raldehyde-treated erythrocytes (to test lectinlike or other nonspecifi c binding sites). Phagocytosis and superoxide anion production (oxydat ive burst) were measured. Results: Granulocytes of ICU patients compar ed with those of non-ICU, noninfected patients exhibited a substantial decrease of zymosan ingestion (P < .05), whereas phagocytosis of othe r particles was normal. Monocytes from the ICU patients, compared with those of the non-ICU, noninfected patients, displayed an unselective overall decrease of phagocytic ability for the three particle types (P < .05). The phagocytosic activity of the three membrane receptor spec ies of blood monocytes and granulocytes of ICU patients was not signif icantly modified by the IVIG infusion. For both monocytes and granuloc ytes, no significant improvement was observed in the fraction of cells that ingested at least one foreign particle and the mean number of pa rticles per cell having phagocytized at least one foreign particle. Gr anulocyte and monocyte functions were also tested by the production of reduced ferricytochrome and no significant improvement in the oxydati ve burst was observed after infusion of IVIG. Conclusion: Infected ICU patients display a deficiency of phagocytosis membrane receptors of b lood granulocytes and monocytes. The addition of IVIG to standard ther apy does not improve the phagocytic activity of ICU patients with noso comial pneumonia. (C) 1997 by W.B. Saunders Company.