TLR4 and aspergillosis: Finally, functional alterations of neutrophils after alloHSCT may also depend on genetic variants of pattern recognition receptors (PPRs) of donor origin.106,107 For instance, extensive studies on HDs and their corresponding recipients demonstrated that hyporesponsive Toll-like receptor 4 (TLR4)106 or pentraxin 3107 genetic variants in HSC donor-derived neutrophils might render alloHSCT patients more susceptible to aspergillosis by affecting anti-fungal neutrophil activity.