Role of Kaposi's sarcoma cells in recruitment of circulating leukocytes: implications in pathogenesis.

Objective: We sought to identify and characterize mechanisms of interaction between Kaposi's sarcoma cells and circulating leukocytes leading to leukocyte migration into the lesion.

Study design/methods: By using static and dynamic adhesion models, we measured the ability of late-stage KSY1 cells to support adhesion and transmigration of peripheral blood lymphocytes (PBL).

Results: We showed that resting as well as TNF-alpha- or PMA-activated KSY1 cells supported adhesion and transmigration of PBL with a higher efficiency compared with normal endothelial cells. The LFA1/ICAM1 pathway was totally involved in PBL adhesion to resting or TNF-alpha-activated KSY1 cells and partially responsible for adhesion to PMA-activated KSY1 cells. No inhibition of adhesion was observed by blockage of the VLA4 pathway. Under flow conditions, PBL/KSY1 cell interaction was totally dependent on L-selectin.

Conclusion: Our data indicate that KS cells mimic an endothelium-like structure by regulating extravasation of lymphocytes into lesions.