TLR9 and hemophagocytic syndrome: As oppose to murine FHL, the MAS model has both a type I and type II interferon response due to TLR9 stimulation resulting in an immune response of both innate and adaptive compartments with a milder contribution of T cells and an overall milder phenotype with mice universally not succumbing to TLR9 repeated stimulation and exhibiting milder features of HLH physiology28,29,35.