ASML-exosomes and leukocyte proliferation. Lymphocytes were stimulated for 72 h as indicated with/without ASML-exosomes. Where indicated, cultures additionally contained ASML lysate-pulsed DC (LNC:DC = 10:1). (A) Mean ± SD (triplicates) of 3H-thymidine incorporation. (B) Examples of CFSE dilution in LNC and SC cultured for 72 h and mean percentage (triplicates) of cells that did progress through 0–4 cycles. Significant differences to cultures not containing ASML-exosomes are shown. (C) BMC-derived DC were cultured as described in MM. During the last 24 h of culture in the presence of LPS, ASML-exosomes were added where indicated: Mean percent ± SD (3 experiments) of CD11b+, CD11c+, CD80+, CD86+, MHCII+, IFNγ+ and CXCR4+ cells (flow-cytometry). (A,C) Significant differences in the presence of ASML-exosomes: *. Exosomes inhibit lymphocyte proliferation, which can be circumvented by activated DC.