I am doing the intracellular staining of IL-22 for intestinal lamina propria cells now. And after staining the cell surface antibody, I stimulated cells with PMA(50ng/ml), ionomycin(750ng/ml), and brefeldin A and incubated cells in 37℃, CO2 incubator for 4h. However, through FACS, I didn't detect the production of IL-22. What's more, I also have a failure when stimulating cells with rmIL-23(50ng/ml), GolgiStop and GolgiPlug.

I don't know what wrong is during my experiment. Is there any good suggestion for me? Thank you.