Protection against reticuloendotheliosis virus-strain T tumours is associated with JMV-1 culture supernatant-enhanced natural killer cell activity.
One-day-old chicks were inoculated intraperitoneally with cell-free JMV-1 culture supernatant and were subsequently challenged with a lethal dose of RECC-CU60 tumour cells at either 7 or 12 days of age. A significant reduction in mortality was evidenced in chicks that had been inoculated with JMV-1 culture supernatant prior to RECC-CU60 tumour cell challenge at 12 days of age, compared with all other treatment groups. Reducing the serum content of JMV-1 culture medium or changing the base medium in which the JMV-1 cells were grown did not affect the reduction in mortality, demonstrating that the protective effects against RECC-CU60 tumour cell challenge were a result of factors secreted into the culture medium by JMV-1 cells. Development of natural killer (NK) cell activity correlated with findings in the RECC-CU60 tumour cell challenge studies. Inoculation of 1-day-old chicks with JMV-1 culture supernatant resulted in a significant increase in NK cell activity in spleens taken from JMV-1 inoculated chicks 12 days later, when compared with spleens taken from chicks in all other treatment groups. Inoculation of chicks with RECC-CU60 tumour cells caused a suppression of their NK cell activity. Treatment of chicks with JMV-1 supernatant at day of age, prior to RECC-CU60 tumour cell challenge restored and significantly enhanced their NK cell activity. These results suggest that the JMV-1 cell line secretes lymphokines that protect against RECC-CU60 tumour cell challenge by directly or indirectly stimulating NK cell activity.
Keller
L H
LH
Laboratory of Avian Medicine and Pathology, New Bolton Center, University of Pennsylvania, School of Veterinary Medicine, Kennett Square, PA, USA.