FIGURE 2.

Endometriotic tissue–derived exosomes (exo) carry NKG2D ligands that downregulate the NKG2D receptor on PBMCs from healthy donors. (A) Immunoelectron micrographs of endometriotic tissue exosomes expressing the NKG2D ligands MICA/B and ULBP1-3. (B) Immunoflow cytometry of endometriotic tissue exosomes captured on mAb-coated latex beads showing surface expression of members of the MICA/B and ULBP families. The black curve represents negative controls with isotype-matched mAbs. (C) MICA/B and ULBP1-3 expression, measured by MFI normalized to isotype-matched mAb control (= 1), on endometriotic tissue- and endometriosis serum exosomes; note the higher ULBP ligand expression on endometriotic tissue exosomes (n = 4). (D) A representative experiment showing downregulation of the NKG2D receptor expression on PBMCs from healthy donors, assessed by MFI before and after 24-h incubation with native endometriotic-tissue exosomes or with the same exosomes blocked by anti-CD63 Abs. Isotype-matched control mAbs (DAKO) were used in the negative control. (E) Average results of seven experiments like the one shown in (D), measuring NKG2D receptor downregulation in the absence and presence of native or blocked exosomes from endometriotic tissue, p < 0.001. (F and G) Average results of six experiments with endometriosis serum exosomes (F) and four experiments with healthy donors’ serum exosomes (G) like the ones shown in (D) and (E).