Enhancement of the increase in intracellular calcium concentration in stimulated neutrophils by Mycoplasma hyopneumoniae.

Neutrophils isolated from the peripheral blood of pigs free of infection with Mycoplasma hyopneumoniae were loaded with a fluorescent indicator (Fura-2) for detection of cytosolic free calcium concentration. The kinetics of the intracellular calcium flux were examined after incubation with or without a pathogenic or a non-pathogenic strain of M. hyopneumoniae. The basal intracellular calcium concentration was not altered by incubation with M. hyopneumoniae. However, the relative increase in cytoplasmic calcium concentration caused by the addition of opsonized zymosan was significantly (p < 0.05) higher in neutrophils incubated with M. hyopneumoniae as compared to neutrophils not incubated with M. hyopneumoniae. Additionally, after zymosan stimulation, the intracellular calcium concentration was greater in neutrophils incubated with a pathogenic strain of M. hyopneumoniae than in those incubated with a non-pathogenic strain. This suggests that M. hyopneumoniae alters the signal transduction mechanisms in neutrophils and that this alteration may be related to virulence.