Sepideh Kamalbeik, Mehran Kouchek, Majid Baseri Salehi, Fatemeh Fallah, Mohammad Ali Malekan and Haleh Talaie
Accepted Abstracts: J Clin Cell Immunol
Microvesicles are small cell-derived membrane vesicles shed from cells during activation or apoptosis. In peripheral blood are found leucocyte-, thrombocyte-, and endothelial-derived microvesicles. Peripheral blood microvesicles are known to participate in coagulation, inflammation and immune response. In the present study phenotype and size distribution of monocyte-like cell line THP-1 microvesicles were evaluated. Microvesicles from intact, TNFα or IFNγ activatedTHP-1 were fractionated from cell conditioned media. Microvesicle fraction was analyzed by atomic force microscopy and also was stained forCD11a, CD11b, CD11c, CD18, CD31, CD29, CD49d, HLA-DR, CD47, CD54, VEGFR1, CD181, TRAIL, CD120a, CD120b and analyzed by flow cytometry. Atomic force microscopy showed a population of spherical objects characterized by the height distribution within 50-400 nm with a peak at 200 nm. Particle size analysis of a 2×2 nm field detected large 700 nm microvesicles in addition to that having the 230 nm mean size. Microvesicles derived from intact THP-1 bore CD11a, CD31, CD29, CD49d, CD47, VEGFR1, CD181, TRAIL, CD120a, CD120b. After TNFαactivation, THP-1 cellsproduced more CD11а+, CD18+, CD54+, VEGF-R1+, CD120b+ microvesicles than intact cells. Activation of THP-1 by TNFα or IFNγ led to the increase in CD54 fluorescence intensity on THP-1-derived microvesicles. Thus, intact or activated THP-1 cells produce microvesicles 50-700 nm in diameter, with the peak at 200 nm. Intact THP-1-derived microvesicles bear adhesion molecules, cytokine and growth factor receptors. Activation of THP-1 by TNFα or IFNγ leads to the increase in production of CD11а+, CD18+, VEGF-R1+, CD120b+, CD54+ microvesicles.