Blastocystis STs 1–3 secrete exosomes (30–100 nm sized) that, when added to human leukemia monocytic cells (THP-1 line), caused different effects on the expression of proinflammatory (IL-6 and TNF-α) and anti-inflammatory (IL-4 and IL-10) cytokines: ST1 upregulated IL-6 and TNF-α concomitant to IL-4 and IL-10 downregulation, ST2/ST3 downregulated IL-10 and ST3 upregulated IL-6 [166]. This evidence concerns the gene IL4 and leukemia.