Th1/Th2 cytokine panel determination using cytometric bead array (CBA) assay. Human PBMCs were treated with B. anthracis cell wall preparation and various elements of anthrax toxin, either individually or in combination, for 72 h. Supernatants were harvested and assayed to determine the concentration of 6 different cytokines. The beads were conjugated with antibodies against corresponding cytokines. Secondary antibody conjugated with fluorescence dye PE was used as a detector. SSC versus FSC were used to locate the position of cytokine beads. The dots from top to bottom represent IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ, respectively. FL3 versus FL2 were used to determine the concentration of cytokines. With increased concentration, the dot plots move to right side. The intensity of the fluorescence is correlated with the concentration of tested cytokines. CW: cell wall, LT: lethal toxin, ET: edema toxin, LF: lethal factor, EF: edema factor, and PA: protective antigen.