CD300a/c modulates TCR mediated Ca2+ flux. CD4+ T cell lines were generated from healthy donors. Cells were loaded with Fluo-4 and Fura-Red. Then, cells were acquired in a flow cytometer, and after a baseline reading of 30 s, anti-CD3 plus anti-CD300a/c mAb or anti-CD3 plus isotype control mAb (black arrows) were added. Goat anti-mouse Ab was added 30 s later to cross-link the primary mAb (grey arrows). Intracellular Ca2+ concentration was measured by the ratio of Fluo-4/Fura Red as a function of time.