Flow cytometric study of immunocompetent cell phenotypes and phagocytosis in CAPD effluent

The immunocompetent cells from peritoneal effluent in 22 stable CAPD patients were studied for surface phenotype distribution and for phagocytic properties by flow cytometry. The following monoclonal antibody couples were employed with direct dual color immunofluorescence: HLA-DR/CD 4, CD 8/CD 11c, Leu 7/CD 16, CD 14/CD 13, and Anti-Leucocyte/CD33. The phagocytic properties of peritoneal macrophages and polymorphs (PMN) were evaluated by the ingestion of 2.02 microns O fluoresceinated microspheres. The same analyses were also performed in peripheral blood. A FACStar laser-operated flow cytometer was employed. A remarkable heterogeneity of CAPD fluid cells was demonstrated, even in the absence of any obvious infection, suggesting the possible occurrence of aborted inflammatory processes. Activated T helper cells, T suppressors (CD8+/CD11+) and Fc gamma+ cells prevailed among lymphocytes, whereas variable amounts of monocytes and PMNs were present. The phagocytic activity of CAPD fluid phagocytes ranged from very depressed to normal values, whereas it was only moderately reduced in blood, suggesting local blocking phenomena, possibly due to interfering metabolites. Flow cytometry is the method of choice for a rapid and accurate analysis of phenotypic and functional properties of cells recovered from various body fluids. This study may be helpful in evaluating local immune response mechanisms in CAPD patients.