Impact on T-cell compartment in the lungs of neonatal mice following influenza A or house dust mite exposure. Groups of 8-day-old mice were either infected with influenza A, PBS treated, or exposed to HDM for 7 consecutive days and T cells evaluated by flow cytometry at day 7 p.i. or 24 h after last HDM exposure. (a, b) Absolute number of CD4+ and CD8+ T cells (CD3+), their activation states (CD69+), and expression of Th2 cell surface marker, T1/ST2. (c) Absolute number of DX5+ (CD3+) NK-T cells. For all data, n=5–6 mice per group. One of two representative experiments is shown. Data represent mean±s.e.m. P<0.05 compared with *PBS; ‡Flu; §HDM, respectively. H&E, hematoxylin and eosin; HDM, house dust mite; PBS, phosphate-buffered saline; p.i., post infection.