Neutrophil granulocytes (PMN) are our primary defence cells against bacteria, fungi, parasites, or micro-thrombi. Their main weapons and signals are the reactive oxygen species (ROS), H2O2 being mother ROS, radicalic OH and non-radicalic 1ΔO2* being the two daughter ROS. 1ΔO2* is the most important ROS because it is harmful against non-self and harmless against self. 1ΔO2* is highly reactive against S-H, S-S, or C=C groups and releases photons (hν). The activation of the assembly of their NADPH-oxidase, one main trigger (zymosan A) and one main primer (1ΔO2*/hv) are of great physiological and pathophysiological importance in inflammation and in hemostasis. There is photonic communication: the neutrophils generate different types of photons and they can see them in other cells. The approximate 300-400 nm photons are the main signals and the photons of lowest wave length seem to especially alert them in emergency.