So useful thanks bro 
So maybe its not a localized effect against acne, but a more general or systemic type of immune modulation.
In a previous article I posted awhile back, some recent research called acne a type of immune training that the body overcomes.
“Taken together, our results suggest that isotretinoin may not reduce directly ongoing inflammation in the acne lesions themselves; instead, it modifies mechanisms that control immune homoeostasis”
Acne: A New Model of Immune-Mediated Chronic Inflammatory Skin Disease
acne can be considered as a model of immune-mediated chronic inflammatory skin disease, characterized by an innate immune response that is not able to control P. acnes followed by a Th1-mediated adaptive immune response, that becomes self-maintaining independently from P. acnes itself.
The innate immune system is a lead actor in the protective function of skin
https://onlinelibrary.wiley.com/doi/full/10.1111/jdv.13190