Previous work has shown macrophages in close association with rupturing cysts [17, 31] and the presence of an active chitinase could point to a role for these cells in the breakdown of cysts within the brain. Recognition of chitin by macrophages is size dependent and likely contact dependent [49, 58, 67] . To test this, we cocultured cysts separated from macrophages using 5 mm transwell inserts and assayed for urea and chitinase activity as previously described ( Fig. 2A, 2D ). Our results show no increase in either urea production or chitinase activity from macrophages that have been separated from cysts, confirming that the observed alternative activation is dependent on contact with cysts or cyst antigen.