CSF3 and Systemic capillary leak syndrome: Considering elevated cytokine levels and increased numbers of circulating CD25+ cells reported in several cases [19–21], perivascular mononuclear infiltrates in skin biopsies taken during attacks [14, 22], and the described elevated G-CSF levels and neutrophil counts, a general factor initiating SCLS attacks may be a so far unspecified immune dysregulation.