Cold-stored platelets do not potentiate detrimental monocyte and neutrophil proinflammatory responses in vitro

Abstract

Abstract Cold-stored platelets (CSP) have increased hemostatic function compared to room temperature-stored platelets (RTP), leading to recent FDA conditional approval for CSP transfusion in bleeding patients. However, the immune consequences of CSP transfusion are not well defined. CD62P and CD40L expression is increased in CSP, potentially enhancing interaction with neutrophils (PMN, CD62P:PSGL-1) and monocytes (Mo, CD40L:CD40). We hypothesized CSP would form aggregates with leukocytes more readily than RTP, thereby increasing tissue factor/CD142 expression, inflammasome assembly, and neutrophil extracellular trap (NET) formation – functions potentiated by native platelets. We stored apheresis platelets in plasma (PLT) for 7 days at 22oC (RT) or 4oC (CS), and incubated PLT with freshly isolated PBMC or PMN at a 1:14 ratio. We measured CD142 and Apoptosis-associated speck-like protein containing caspase activation and recruitment domain (ASC) expression by flow cytometry in Mo, and ASC specks and NET formation in PMN using fluorescent microscopy. We found no difference in CD142 or ASC GMFI expression in monocytes incubated with RT or CS PLT, and no difference in ASC specks or NET formation between neutrophils incubated with RT and CS PLT. Therefore, our in vitro study shows CSP do not potentiate detrimental acute proinflammatory responses by monocytes or neutrophils, further supporting CSP use in actively bleeding patients and paving the way for precision transfusion medicine.