Effects of ascorbate on leucocytes: Part I. Effects of ascorbate on neutrophil motility and intracellular cyclic nucleotide levels in vitro.

A preliminary series of experiments indicated that ascorbic acid and calcium and sodium ascorbate in the absence of serum had no stimulatory effect on neutrophil motility. However, when neutrophils were pre-incubated with ascorbate at concentrations between 5 X 10(-2)M and 1 X 10(-1)M in the presence of fresh normal autologous serum (5% final concentration) considerable stimulation of random motility and migration towards the leuco-attractants C5a and casein was observed. The serum factor required for ascorbate-mediated enhanced locomotion was heat unstable and was probably not serum albumin since no stimulation of cell migration was observed when serum was replaced with varying amounts of human serum albumin. Calcium ascorbate was the most potent stimulant of neutrophil motility. Concentrations of calcium and sodium ascorbate which increased migration promoted elevation of intracellular cyclic guanosine monophosphate (cGMP) levels, but not of adenosine monophosphate (cAMP). These same concentrations also caused increased glyclytic activity. It is suggested that the enhanced neutrophil motility mediated by ascorbic acid and calcium and sodium ascorbate in the presence of serum may be due to increased cGMP and/or glycolysis.