Trichinella spiralis reinfection: macrophage activity in BALB/c mice.

The role of macrophages and their products--nitric oxide (NO) and superoxide anion (O(2) (-))--were examined in BALB/c mice reinfected with Trichinella spiralis. Mice were infected twice with 400 T. spiralis larvae; the secondary infection was performed 60 days after the primary one. Adult T. spiralis in intestines were detected from 5 to 20 days postprimary infection (dpi), and postreinfection (dpri), but the intensity of worm expulsion was greater and quicker after the reinfection. The highest muscle larvae numbers were detected from 60 dpi till 90 dpi (30 dpri), and thereafter, a great reduction was noted. The high numbers of macrophages in the peritoneal cavity of infected mice were obtained at 20 dpi, but the highest numbers of these cells from 10 to 30 dpri were observed. The production of NO by macrophages in infected mice was suppressed at 5 dpi, and then, NO release increased until 60 dpi. On the contrary, the long-lasting (5-30 dpri) suppression of NO production after T. spiralis reinfection was observed. The levels of NO in plasma and urine were lower in infected mice till 20 dpi; there were no differences in plasma and urine NO level after the reinfection in comparison to control uninfected animals. The production of O(2) (-) in peritoneal macrophages was inhibited during the first 2 weeks after infection, but the reinfection caused great increase in O(2) (-) production lasting 30 days.