IFN-I signaling is involved in connected recruitment and activation of NK cells to CD11b⁺Ly-6C^hi monocytes.

<p><b>(A)</b> NK cell infiltration of infected BL/6 or <i>IFNAR</i> KO mice. <b>(B)</b> Total accumulated NK cell number. Cells were prepared from vaginal tract (VT) and iliac LN (ILN) by collagenase digestion at 24, 48, and 72 h pi and used for analysis of NK cells. Values in dot-plots denote the average percentages of NK1.1⁺DX5⁺ NK cells derived from four independent samples after gating on CD3-negative cells at 48 h pi. <b>(C)</b> Frequency of IFN-γ or granzyme B-producing cells among NK cells. The production of IFN-γ and granzyme B by CD3⁻NK1.1⁺DX5⁺ NK cells was determined by intracellular staining after stimulation of vaginal NK cells with PMA plus ionomycin at 48 h pi. Values in histograms represent the average percentages of IFN-γ or granzyme B-producing cells among CD3⁻NK1.1⁺DX5⁺ NK cells. <b>(D)</b> Absolute number of IFN-γ or granzyme B-producing NK cells. Total number of IFN-γ or granzyme B-producing CD3⁻NK1.1⁺DX5⁺ NK cells in vaginal tract was enumerated by flow cytometric analysis using intracellular and surface staining at 48 h pi. <b>(E)</b> Secreted IFN-γ levels in vaginal tract. Secreted IFN-γ levels were determined by ELISA at 48 h pi using vaginal lavages. Data in bar chart represent the average ± SD of values derived from three individual experiments (<i>n</i> = 4–5). **, <i>p</i><0.01; ***, <i>p</i><0.001 compared with the levels of <i>IFNAR</i> KO mice.