[Phenotypic expression and functional manifestation of fetal and maternal natural killer (NK) cells]

The NK cells, considered to play an important role in host defense, are reported to show heterogeneity during the cellular development. To document the heterogeneity, studies were carried out on the phenotypic expressions, the cytolytic activities, the responsiveness to recombinant interleukin 2 (rIL-2) and on the ultrastructure of the NK cells of the blood obtained at the time of delivery from 24 pairs of mothers and umbilical cords. The phenotypic expressions were Leu7+-11-(6.2 +/- 2.1%, SD), Leu7+-11+(5.6 +/- 1.8), and Leu7--11+(5.5 +/- 2.1) in the maternal NK cells, whereas the cord blood NK cells expressed only Leu7--11+(8.2 +/- 2.4). The cytolytic effect of the NK cells on K562 target cells was assayed by a method to determine ATP release. The activity of the maternal blood NK cells was 80.4 +/- 10.5%, SD whereas the cord blood samples showed only 40.5 +/- 8.5, after 4-hour incubation; the difference between the maternal and cord NK cells was statistically significant (p less than 0.01). The NK cells were incubated with rIL-2 (10 units), and the cytolytic activity was determined. The activity of the cord blood NK cells was significantly enhanced already after incubation for 2 hours and it lasted until incubation had continued for 4 hours. However, the rIL-2 effect was not significant after incubation for 5 hours. On the other hand, the activity of the maternal blood NK cells was not influenced significantly by rIL-2.(ABSTRACT TRUNCATED AT 250 WORDS)