Ah, thank you whoever, for giving us WHITE uniforms.
Oxyclean or whatever powdered oxygen-based crap you can find in the store. Wet the sleeve really well and apply a paste of water and the oxy-stuff. Inside too. GENTLY scrub it with a SOFT toothbrush. Don't go crazy, it will tear up the material. Rinse, repeat. It may not completely come out, but that's the best you're gonna do.
When you're done, turn the jacket inside out and wash it in the washing machine (remove all the buttons) on the delicate cycle, in warm water (not hot, it will shrink), with a little (1/4 cup) "Tide with Bleach". If your dryer actually has a no-heat tumble cycle, use that, otherwise, hang it carefully on a wooden or plastic hangar (metal will rust and fvck it up more) to dry. Then take it to the cleaners and specify you do not want dry cleaning, just a pressing.
disclaimer: I've done this with both Abott's and issued crap (i.e. velcro collar) chokers. Just make sure you keep an eye on em, don't try to do this while playing 40 Hands or during a Power Hour. You crazy college kids...
Side note: The gentle wash cycle/Tide thing will take out any "yellowing" that may occur if you left your chokers in the plastic dry cleaning bag and left them in the closet for a year or so (i.e. wear em to commissioning, wear them 1.5 yrs later at winging). The best bet is to wash em yourself, and have the cleaners press them. That, or take them out of that bag and let them breathe, the dry cleaning chemicals yellow the cloth over time.