The neonatal immune system is adapted to address ongoing tissue development and microbiome colonization. In addition to maternal antibodies, myeloid-derived suppressor cells (MDSCs) are more numerous in neonates than in adults and limit T-cell activation. New data from mouse models suggest that neonatal platelets induce monocytes to differentiate into MDSCs that suppress the adaptive immune response in neonates. Neonatal and adult mouse platelets not only express different proteomes, but monocytes cocultured with neonatal platelet releasates (proteins and other bioactive molecules released from activated platelets) also limited CD4+ and CD8+ T-cell proliferation. MDSC differentiation in neonates appears to be driven in part by the elevated levels of prostaglandin E2 (PGE2) produced and released by neonatal platelets compared with adult platelets; in addition, blocking a key receptor of PGE2 signaling led to a significant decrease in MDSC-associated markers. Platelets are not only mediators of thrombosis, but they also directly and indirectly regulate the immune response differently in neonates and adults. Future studies are needed to better understand how neonatal platelets differ from adult platelets and how these differences affect platelet transfusions in premature infants and neonates.
References:
- Maurya P, O’Reilly D, Hilt ZT, Livada AC, et al. Neonatal platelets differentiate monocytes to a myeloid-derived suppressor cell phenotype. Blood. 2026 Jul 30;148(5):610-622. doi: 10.1182/blood.2025028734. PMID: 41980018.
- Liu Y, Yazdanbakhsh K. Neonatal platelets: MDSC-ooling the monocytes. Blood. 2026 Jul 30;148(5):531-532. doi: 10.1182/blood.2026034150. PMID: 42486809.
