Percentage of monocytes and NK cells in PBMC after ML29 vaccination. A) In the 8 SIV-infected, ML29-vaccinated monkeys there is a significant reduction of the percentage of circulating NK (CD16+) cells one week after vaccination. B) Reduction of the NK (CD16+) population in four healthy (non-SIV-infected) animals one week after ML29 vaccination. C) In the 11 SIV-infected, arenavirus-vaccinated monkeys there is a slight increase in monocytes a week after ML29 vaccination. D) This increase is also observed in non-SIV-infected control monkeys.