Idiopathic capillary leak syndrome: Evidence of CD8-positive lymphocytes surrounding damaged endothelial cells

Idiopathic capillary leak syndrome (ICLS) is a lethal disease characterized by recurrent fluid extravasation leading to hypovolemic shock underlaid by marked hemoconcentration (hematocrit as high as 80%).(1) Only 30 patients with ICLS have been reported in the literature, and the pathogenesis remains unknown. Extravasation of intravascular fluid, with similar clinical symptoms, is also a well-known complication of systemic administration of recombinant (r)IL-2.(2) In this last condition, direct in vivo interaction between IL-2-activated cells (probably LAK cells) and endothelium results in cytotoxicity to endothelial cells.(3) We previously provided evidence that cytokines participate in the pathogenesis of ICLS by demonstrating the appearance of IL-2 receptor-positive cells during attacks in a patient with this disease.(4) Now we have studied the pathology of the same patient, who died during an attack, and have found that in the skin there were perivascular infiltrates of CD8 lymphocytes surrounding damaged endothelial cells, a picture similar to that of rIL2-dependent capillary leak syndrome (CLS).