Introduction 3 3 1 2 3 4 P2 receptors 5 8 1 2 4 6 11 12 13 14 5 9 10 2+ 1 11 12 13 11 15 2 4 6 16 18 4 6 16 18 14 5 9 19 20 20 23 8 24 25 1 7 + + 2+ 22 26 P2 receptors and migration of neutrophils 27 28 2+ 27 29 33 2+ 34 36 37 103 2 2U 4 6 1 2 38 2 11 39 40 7 41 P2 receptors and recruitment of human eosinophils 1 2 4 6 11 14 1 4 7 23 42 44 23 26 45 2+ 42 44 23 42 44 26 46 46 P2 receptors and mast cells 47 48 1 4 7 47 1 2 11 12 13 48 49 2 50 P2 receptors and lymphocytes 51 53 30 54 57 58 59 2+ 60 61 1 2 4 6 38 7 22 62 63 1 2 4 7 59 1 4 7 22 64 65 + ++ 65 65 1 2 4 6 11 12 13 66 7 67 70 7 71 72 7 73 P2 receptor in monocyte/macrophages 74 30 38 75 78 1 2 4 6 11 12 13 1 4 7 38 66 79 7 22 7 2 4 6 30 80 81 22 30 77 79 82 83 84 38 50 85 46 86 89 P2 receptors in dendritic cells 90 92 93 94 1 4 5 7 1 2 4 6 11 12 13 14 95 99 1 2 4 96 2 1 100 2+ 6 101 i/o 1 2 4 6 11 1 4 7 100 1 2 5 1 7 4 2 12 12 102 11 21 + + + 98 22 10 5 102 6 101 In sum, activation of DCs by extracellular nucleotides leads to multiple cell responses, which results in a direct migration of DCs and also maybe indirect (DC-mediated) recruitment of other immune cells to the site of inflammation. Conclusion Over the last few years, several studies have implied that extracellular nucleotides which are actively released or diffuse out of mechanically stressed, infected or injured cells might be involved in the early recruitment of immune cells to the site of inflammation/cell damage. In these in vitro experiments, it has been shown that extracellular nucleotides (mainly by activating P2YR subtypes) are direct chemoattractants for human neutrophils, eosinophils and DCs and/or they can modulate the chemokine production of eosinophils, monocytes and DCs, which might then influence the migration capacity of other immune cells. However, whether nucleotides play a role in the migration of immune cells in vivo still remains to be elucidated.