Granulocyte Colony—Stimulating Factor Multiplies Normal Blood ROS Generation at Less than 1 µg/l

Abstract

Background: The neutrophils (PMN) are our main blood cells to combat fungi, bacteria, and fibrin. For normal function, an activated PMN generates a certain concentration of reactive oxygen species (ROS). If the generated blood ROS concentration is too low, then fungi, bacteria or fibrin might threaten the life of the patient, and it could be of great medical interest to stimulate PMN by physiologic drugs. Granulocyte-Colony Stimulating Factor (G-CSF) is a cell hormone that increases the cell number of PMN and that stimulates the individual PMN. The blood ROS generation assay (BRGA) is an innovative physiologic test to monitor the ROS generation of PMN in blood. Here the ROS generating action of G-CSF on normal PMN is quantified. Material and Methods: 40 μl 0 - 10.3 ng/ml (final conc.) G-CSF (in 5% human albumin) in black Brand? 781608 high quality polystyrene F-microwells was incubated in triplicate with 125 μl Hanks’ balanced salt solution (HBSS; modified without phenol red) and 10 μl normal citrated blood. Immediately (BRGA) or after 60 min (BRGA-60-) 10 μl 5 mM luminol sodium salt in 0.9% NaCl and 10 μl 0 or 36 μg/ml zymosan A in 0.9% NaCl was added. The photons were counted within 0 - 318 min (37°C) in a photons-multiplying microtiter plate luminometer. At about 0.5 t-maxn (0.5 fold the time to normal maximum) the approx. SC200 of G-CSF was determined. Results and Discussion: The approx. SC200 of G-CSF on normal blood ROS generation was 0.2 μg/l (=20 IU/ml). In clinical situations where an increased blood ROS generation is pharmacologically required, few micrograms of G-CSF could be a sufficient dosage for an adult patient. The BRGA helps to find out the correct stimulating G-CSF dosage for each individual. An enhanced PMN function could favor a better clinical outcome in situations of wanted increase of the innate immunology or in cellular fibrinolysis. G-CSF plasma concentrations of 0.1 - 1 μg/l might favor singlet oxygen generation without immunosuppression or cell fragment-induced thrombin generation.