High Light Scatter by Neutrophils in the Bayer-Technicon H*2 Analyzer: A Screening Test of Morphologically Defective Responsiveness to in vitro Chemotactic Stimulation

Abstract

Summary:The Bayer-Technicon H*2 haematological analyser provides differential white blood cell count, including the assay of polymorphonuclear leukocytes by light scattering and the absorbance increase following the cytochemical reaction for myeloperoxidase. The mean value of polymoφhonucleaΓ leukocytes scatter, which reflects polymorphonuclear leukocytes volume, is printed in a separate report "for laboratory use only" s a ybar value in arbitrary units.In certain patients neutrophils displayed an unreported correlation between polymbiphonuclear leukocytes high ybar basal values (^ 37.00 arbitrary units) (determined on the H*2) and a defective response in vitro to the chemoattractant, formyl-methionyl-leucyl-phenylalanine (determined by microscopic evaluation of polymorphonuclear leukocytes shape change (polarization)). The patients showing no polymorphonuclear leukocyte response or a defective one to formyl-methionyl-leucyl-phenylalanine were all affected by "Systemic Inflammatory Response Syndrome (SIRS)". Therefore the predictive value of the positive test for SIRS is 100%. On the other hand 8.8% of SIRS patients had polymorphonuclear leukocytes < 37.00 arbitrary units of ybar basal value and a "normal" response to formyl-methionyl-leucyl-phenylalanine; the predictive value of the negative test being 90%.Since we demonstrated in vitro a dose-dependent deactivation of endotoxin or lipopolysaccharide-pretreated polymorphonuclear leukocytes, the "normal" response to formyl-methionyl-leucyl-phenylal nine of the "false negative" cases may occur because the endotoxaemia in these patients is too low to prevent it. Thus, high polymorphonuclear leukocyte scatter values on the H*2 allows the identification of a group of critically ill patients in whom activated neutrophils do not respond to umher Stimulation by polymorphonuclear leukocyte polarization, a shape change that is characteristic of migrating cells and essential for chemotaxis. Introductionlight scattermg with aggregometry (2), using a spectrofluorometric test (3), or the microscopic count of polarIn eertain patients with a depressed white blood cell ^ bipolar cells (lj 4)i Microscopic evaluation of forcount, it has been shown that the polymorphonuclear myl-methionyl-leucyl-phenylalanine-induced polymorleukocytes display a defective response to the chemoat-phonuclear leukocyte bipolar shape formation on smears tractant, formyl-methionyUeucyl-phenylalanine (1). frorn whole blood is easier, more rapid to perform and This response can be evaluated in vitro by treating poly-the percentage of biplar cells correlates very well with morphonuclear leukocytes with formyl-methionyl-polymoφhonuclear leukocyte migration assay (l, 4).

Phagocytic Activity and Oxidative Burst of Granulocytes in Persons with Myeloperoxidase Deficiency

“…Normal blood controls of 5 healthy persons, aged between 25-45 years, were selected, based on their myeloperoxidase activity. Founded on measurements of several thousand healthy donors, the mean peroxidase index was arbitrarily set as "zero" by the manufacturer (5,6) and the values of the mean peroxidase index between -1-10 and -10 were considered as 'normal'. The mean peroxidase index of an individual sample was calculated by the H3 according to the equation:…”

“…2 ) Enzymes: Catalase,EC 1.11.1.6 Eosinophil peroxidase, EC 1.11.1.-Myeloperoxidase, EC 1.11.1.7 NADPH-oxidase, EC 1.6.99. 6 Superoxide dismutase, EC 1.15.1. 1 an automatic blood cell counter, the Bayer/Technicon H3.…”