In vitro activation up-regulates BLT1 surface expression on T cells. (A) Dendritic cell (DC) primed naive CD4⁺ T cells up-regulate surface BLT1 expression, and this expression is first seen on day 6 of activation. Representative data showing scatter plot (top left panel), differentiation and activation markers (top right panel), histogram plot of BLT1 expression (bottom left panel), and CFSE labeling demonstrating BLT1 expression on divided cells at day 6 (bottom right panel). These data are representative of 3 to 6 different experiments. (B) DC primed CD8⁺ T cells also up-regulate surface BLT1 expression; shown is 1 representative experiment of 4. (C-D) In vitro–activated human effector T cells chemotax to LTB₄ and are inhibited by CP-105696. These data are representative of at least 3 separate experiments. (E) PHA-activated γδ and Vα24 cells up-regulate surface BLT1 expression. γδ and Vα24 cells were isolated from PBMCs and activated with PHA as described in “Patients, materials, and methods” (top and bottom rows, respectively). Representative examples of preactivation ex vivo BLT1 surface expression in PBMCs (panels), and postactivation in vitro BLT1 surface expression (right panels) are shown. These data are representative of 4 (γδ) and 6 (Vα24) separate experiments. (F) NKT cell clones flux calcium when stimulated with LTB₄. These data are representative of experiments on 4 separate NKT cell clones.