Early recruitment of Gr1⁺ cells occurs on D12 and precedes accumulation of activated T cells.

<p>B6 mice were infected with ∼100 CFU <i>M.tuberculosis</i> via the aerosol route and at specific times after infection, cells were isolated from the lung and the percentage of Gr1⁺ neutrophils (a) or Gr1⁺ monocytes (b) were determined by flow cytometry. In some B6 <i>M.tuberculosis</i>-infected mice, lungs were fixed in 10% formalin, embedded in paraffin and the accumulation of Gr1⁺ cells (green) and CD3⁺ T cells (red) determined by immunofluorescence (c). The data points represent the mean (±SD) of values from four-five mice (a,b). _*, <i>p</i>≤0.05, _**, <i>p</i>≤0.005. _***, <i>p</i>≤0.0005 over Day 0 samples.