Stimulated intraphagosomal release of eosinophil peroxidase and acid phosphatase in the rats spontaneously infected with Mycoplasma pulmonis: a cytochemical study.

In this study we performed a cytochemical comparison of peroxidase and acid phosphatase activities in peritoneal eosinophils from specific pathogen-free (SPF) and Mycoplasma pulmonis-infected rats. When eosinophils ingested polystyrene particles for 120 min, peroxidase- and acid phosphatase-positive specific granules, as well as small granules, fused to phagosomes. Unusual peroxidase activity was detected in some particle-containing phagosomes in 6.8% of eosinophils from control SPF rats and 31% of those from infected rats. Intense acid phosphatase activity was also demonstrated in some phagosomes in 4 and 20% of eosinophils from control and infected rats, respectively. The rate of peroxidase-positive and acid phosphatase-positive phagosomes to all ingested phagosomes was 8.1 and 7.3% in control rats and rose to 41.3 and 31.1% in those infected, respectively. The population of eosinophils (18%) in the control peritoneal cells did not change after infection (16.6%). These results suggest that the intraphagosomal release of lysosomal enzymes was significantly stimulated in peritoneal eosinophils of the rats spontaneously infected with M. pulmonis.