FIG. 5.

NK cells from subjects with N. americanus infection secrete IFN-γ. Whole-blood samples from egg-negative individuals from areas of nonendemicity (in the United States), egg-negative individuals from areas of endemicity (in Brazil), and egg-positive individuals from areas of endemicity (in Brazil) was incubated for 24 h with medium alone (A) or with PMA and ionomycin (B) in the presence of brefeldin A. Cells were then stained with antibodies to CD56/CD16 and CD3 and for intracellular IFN-γ. Data show the percentages of NK cells (CD56⁺ CD16⁺ CD3⁻) staining positive for IFN-γ. The boxes represent group means. The dotted lines represent pairwise comparisons between groups by Necator infection status; P values for each pairwise comparison are included where significant.