Enhanced group A Streptococcus (GAS) clearance by whole blood in the presence of interferon α (IFN-α). A, GAS clearance of blood from patients before, during, and after IFN-α therapy was assessed ex vivo. Patients were followed throughout the course of IFN-α therapy, with some time points missing owing to variable schedules of a few individuals. Open circles indicate untreated patients, and closed circles indicate samples obtained during IFN-α treatment. GAS survival in blood during therapy was compared to survival before therapy start. B, GAS clearance by blood taken from healthy volunteers (closed bars) or from patients 8 weeks after IFN-α therapy (open bars) after addition of IFN-α ex vivo. C and D, Absolut monocyte (C) and neutrophil (D) counts of patients before (open bars) and during (closed bars) IFN-α therapy are shown as box plots, with whiskers denoting 5th–95th percentiles. Experiments show data from a cohort of 8 patients, with 1 sample per patient per time point, or from 5 healthy volunteers. The experiment shown in panel B was repeated at least 3 times in triplicate with 3 individual healthy volunteers or 3 patients (data are means ± standard errors of the mean). Groups in panel A were compared by using the unpaired 2-tailed t test. Data in panel B were analyzed by using 1-way analysis of variance with the post hoc Dunnett multiple comparisons test. *P < .05 and **P < .01.