Characterization of the inflammatory cells in progressing tumor-like alveolar hydatid cysts: 1. Kinetics and composition of inflammatory infiltrates.

The kinetics and composition of leukocytic infiltrates from the biphasically growing parasite biomass and the peritonea of C57BL/6J mice infected intraperitoneally with Echinococcus multilocularis cysts were studied. During the first 6 to 8 weeks postinfection (p.i.) the larval cyst masses (LCM) grew slowly, weighted 1 g and contained 3 to 4 X 10(6) leukocytes/100 mg of LCM. Subsequently, (8 to 16 weeks p.i.) the growth of the LCM was rapid and was accompanied by 3 to 4-fold reduction in the absolute leukocyte count; monocytoid cells, neutrophils, eosinophils and T-lymphocyte significantly decreased during the progressive growth phase of the LCM. The cumulative data show a strong inverse relationship between the mean LCM weights and the absolute or relative counts of intra-LCM leukocytes. The data suggest that high concentrations of intra-LCM leukocytes, especially monocytoid cells and to a lesser degree eosinophils, regulate the growth of the LCM in C57BL/6J mice.