Thomas is a regulatory B cell. You can tell by the red beard, square glasses, and bald head. He has the power of suppressing an immune response, which puts him on the most wanted list of the Federal Bureau of Immunology (FBI). Unfortunately, Claudia, a girl with long purple hair, striking blue eyes and a mole below her left eye, is also a regulatory B cell. She is likewise capable of suppressing an immune response, even though she looks completely different to Thomas. This confusion causes much grief at the FBI, as there are many features that can be used to profile regulatory B cells. To address this, I use the technique of “mass cytometry”, which allows me to characterise the many facial components that have been used to identify regulatory B cells like Thomas and Claudia in a single profile. By using this technique, I have identified an unlikely accomplice of regulatory B cell-induced immune suppression: mast cells. More specifically, I found mast cells like Michele were capable of influencing cells like Thomas to become regulatory in nature. By further understanding how Michele is capable of convincing Thomas to become regulatory, it would allow us to inhibit or even enhance this interaction as a means of treatment against a range of diseases.