Problem: Our previous study indicated that meconium-stained amniotic fluid (turbid AF) possessed a potent chemotactic activity for leukocytes, which may be dependent on interleukin-8. It is not known, however, whether meconium itself possesses this chemotactic activity.
Method of study: Meconium samples were collected from mature neonates with and without turbid AF. A 5% meconium suspension in phosphate buffered saline was prepared and measured for its chemotactic activity for leukocytes using the blind well chamber technique. Concentrations of IL-8, TNFalpha and IL-1beta were also measured with ELISA.
Results: The number of leukocytes that migrated to the meconium suspension (35 +/- 27) was comparable with that of the clear AF (31 +/- 37), but was significantly lower than that of the turbid AF (184 +/- 62, P < 0.0001). The meconium suspension contained much lower levels of IL-8, TNFalpha and IL-1beta than the turbid AF.
Conclusions: Meconium itself exhibits a lower chemotactic activity for polymorphonuclear leukocytes than turbid AF in vitro. The leukocyte chemotactic activity of turbid AF does not originate from meconium itself.