MONITORING OF POLYMORPHONUCLEAR LEUKOCYTE FUNCTIONS IN DIABETES-MELLITUS - A COMPARATIVE-STUDY OF CONVENTIONAL RADIOMETRIC FUNCTION-TESTS AND LOW-LIGHT IMAGING-SYSTEMS

In this study neutrophil (PMN) phagocytic capacity was investigated us ing a conventional radiometric ingestion assay (IN) in comparison with PMN respiratory burst activity assessed by luminol-enhanced chemilumi nescence (LCL) in response to phorbolesters and LCL induction during p hagocytosis of opsonized Staphylococcus aureus (STLCL) in diabetes mel litus and healthy controls. PMN ingestion was measured with H-3-thymid ine-labelled S. aureus in a kinetic radiometric assay. LCL and STLCL w ere assessed in a parallel detecting microtitre-plate luminometer (MTP -Reader). PMN of diabetic subjects showed a highly significant reducti on of peak LCL in response to PMA as well as during phagocytosis of S. aureus (STLCL) compared to non-diabetic controls (p < 0.001 respectiv ely). PMN ingestion in diabetic patients (51.8 +/- 4.6%) was significa ntly reduced compared to controls (78.3 +/- 6.2%) (p < 0.01). The in v itro data displayed impaired PMN oxidative burst activity at glucose c oncentrations greater than or equal to 13.8 mmol/L, whereas PMN IN was significantly reduced at glucose levels greater than or equal to 27.7 5 mmol/L. The control group showed a positive correlation of peak LCL response and IN (p < 0.05) but not of STCL and IN; in diabetic patient s this was also true, but did not reach statistical significance. The data obtained in this study clearly demonstrated impaired PMN respirat ory burst activity and markedly reduced phagocytic PMN functions in di abetic patients ex vivo and in vitro as measured by LCL and by ingesti on of H-3-thymidine-labelled S. aureus suggesting inhibitory effects o f elevated glucose concentrations on various PMN-functions, which migh t be of clinical importance concerning altered host defence.