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E Sommaruga

Publications and source records attributed to E Sommaruga.

10 recordsLinked to original sources
PubMed1993

Nationwide quality control trial on lymphocyte immunophenotyping and flow cytometer performance in Italy.

The Italian Society for Cytometry (Gruppo Italiano di Citometria, GIC) promoted this nationwide large-scale quality control trial on cellular immunophenotyping and flow cytometer performance in 1991. The aim of this independent study was to evaluate instrument performance with calibrated fluorescence microbeads (minimum threshold for FITC, linearity, coefficients of variation and resolution indexes for fluorescence), and to correlate it to the measurement of lyophilized lymphocyte surface immunofluorescence staining with a wide spectrum of antibodies (percentage of positive cells and fluorescence mean intensity). A single send-out was made to 306 laboratories with 350 instruments throughout Italy. Each kit included anonymous vials containing premixed calibrated microbeads, lyophilized human lymphocytes and small aliquots of conjugated monoclonal antibodies, for both single FITC and double FITC/PE staining. Participants were also asked to use their own anti-CD4 monoclonal. A valid answer was returned by 209 laboratories with 221 instruments. Gating was not an assay variable. The minimum sensitivity threshold for FITC ranged from 26.6 to 11,293 MESF, with marked instrument heterogeneity as far as the relationship between FITC threshold and coefficients of variation for fluorescence was concerned. A low FITC threshold also correlated with a good resolution index for low intensity stainings. No performance comparisons among instrument brands and models were made. The lyophilized lymphocyte analysis showed an overall frequency of outliers ranging from 3.2% to 19.7%, with a maximum for CD2 FITC (19.7%) and CD3 + HLA-DR + (12.1%). A strongly negative relationship was evident between the FITC threshold and the number of CD2+ cells, whereas the sensitivity threshold had virtually no effects on the measured level of higher antigen density markers like CD4 and many others. Absolute fluorescence intensity measurements of CD4+ and CD19+ were also made. This study design proved valid and suitable for a large-scale evaluation of both instrument performance and cytometer operators' skill. A number of practical problems were identified among participants, thus stressing the need for more effective educational programmes and technical guidelines.

Flow Cytometry↗
PubMedDate not supplied

Polymorphonuclear cell phagocytosis and surface receptor modulation after extracorporeal circulation.

Polymorphonuclear cells (PMN) from patients treated with hemodialysis (HD) or plasma exchange (PE) were analyzed by flow cytometry to determine modulation in phagocytic capacity and Fc-gamma and C3bi receptor expression following extracorporeal circulation (EC). Fluorescent microbeads (phi 2.02 m) were used in the evaluation of phagocytosis, and phycoerythrin conjugated Leu11c and Leu15 monoclonals identified Fc-gamma and C3bi receptors respectively. The percentage of positive cells and mean receptor density on PMN surfaces were calculated for each antibody before and after the procedures. Fc-gamma receptor expression was reduced overall in HD and PE cases, but unaffected after EC even with specific paraprotein removal. C3bi receptor was normally expressed on PMNs before and after EC, but receptor density on the cell surface increased, and phagocytosis was qualitatively and quantitatively depressed after EC. The resulting effect of EC on PMNs was therefore a temporary increase in C3bi receptor density after the procedure, which was independent of HD or PE technique, of the primary disease, and of the quality of the PE reinfusion solutions, suggesting a procedure-related effect, and a down-regulation of PMN phagocytic activity. Both effects may be related to membrane biocompatibility.

Antigens, Differentiation↗
PubMedDate not supplied

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.

Adult↗