\u03b2-mannosylceramides or salts or solvates thereof in a pharmaceutically acceptable carrier, for use as a Type I NKT cell agonist in conjunction with a therapeutically effective amount of \u03b1-galactosylceramide or a salt or a solvate thereof, andor at least one or more T-cell co-stimulatory molecules, disclosed. A group can include at least one group leader application server node and at least one group member server nodes. The robustness the PLL 12 can be improved by means of a gain control circuit 27, a sign detector 20, a carrier monitoring circuit 28 and an adjustable loop filter 32.