Human neutrophil antigen 3 genotype impacts neutrophil-mediated endothelial cell cytotoxicity in a two-event model of TRALI.

BACKGROUND: Antibodies against human neutrophil antigen (HNA)-3a are associated with severe cases of transfusion-related acute lung injury (TRALI). The HNA-3 system is located on choline transporter-like 2 (CTL-2) protein. CTL-2 is encoded by the gene SLC44A2 and a single-nucleotide polymorphism c.461G>A results in two antigens: HNA-3a and HNA-3b. Three HNA-3 genotypes/ phenotypes exist: HNA-3aa, HNA-3bb, and HNA-3ab. Two different pathways of anti-HNA-3a TRALI have been described: a two-hit neutrophil-dependent pathway and a one-hit neutrophil-independent pathway. However, it is not clear whether HNA-3ab heterozygous patients have a lower risk of anti-HNA-3a-mediated TRALI compared to HNA-3aa homozygous patients. MATERIALS AND METHODS: Healthy volunteers were genotyped for HNA-3 by real-time polymerase chain reaction, and phenotyped for HNA-3a by granulocyte immunofluorescence test (GIFT) and granulocyte agglutination test (GAT) against two donor sera containing anti-HNA-3a antibodies. The two sera were also used in in vitro models of human pulmonary microvascular endothelial cell (HLMVEC) cytotoxicity to investigate pathways of TRALI development. RESULTS: For both anti-HNA-3a sera, GIFT results matched the genotype, with a lower GIFT ratio for HNA-3ab neutrophils compared to HNA-3aa neutrophils, whereas GAT results showed no difference in agglutination. HLMVEC cytotoxicity was not observed in a one-hit neutrophil-independent model but was observed in a two-hit neutrophil-dependent model. Differences in cytotoxicity were observed between the two anti-HNA-3a sera used. Consistent with reduced HNA-3a antigen density as measured by GIFT, HNA-3ab neutrophils mediated less HLMVEC cytotoxicity than HNA-3aa neutrophils. CONCLUSION: HNA-3 genotype and HNA-3a antigen expression impacted the severity of anti-HNA-3a-mediated HLMVEC cytotoxicity in a two-hit neutrophil-dependent model of TRALI. Different HNA-3a antibodies might also impact the magnitude of HLMVEC cytotoxicity.

An Ovine Model of Hemorrhagic Shock and Resuscitation, to Assess Recovery of Tissue Oxygen Delivery and Oxygen Debt, and Inform Patient Blood Management.

BACKGROUND: Aggressive fluid or blood component transfusion for severe hemorrhagic shock may restore macrocirculatory parameters, but not always improve microcirculatory perfusion and tissue oxygen delivery. We established an ovine model of hemorrhagic shock to systematically assess tissue oxygen delivery and repayment of oxygen debt; appropriate outcomes to guide Patient Blood Management. METHODS: Female Dorset-cross sheep were anesthetized, intubated, and subjected to comprehensive macrohemodynamic, regional tissue oxygen saturation (StO2), sublingual capillary imaging, and arterial lactate monitoring confirmed by invasive organ-specific microvascular perfusion, oxygen pressure, and lactate/pyruvate levels in brain, kidney, liver, and skeletal muscle. Shock was induced by stepwise withdrawal of venous blood until MAP was 30 mm Hg, mixed venous oxygen saturation (SvO2) < 60%, and arterial lactate >4 mM. Resuscitation with PlasmaLyte® was dosed to achieve MAP > 65 mm Hg. RESULTS: Hemorrhage impacted primary outcomes between baseline and development of shock: MAP 89 ±â€Š5 to 31 ±â€Š5 mm Hg (P < 0.01), SvO2 70 ±â€Š7 to 23 ±â€Š8% (P < 0.05), cerebral regional tissue StO2 77 ±â€Š11 to 65 ±â€Š9% (P < 0.01), peripheral muscle StO2 66 ±â€Š8 to 16 ±â€Š9% (P < 0.01), arterial lactate 1.5 ±â€Š1.0 to 5.1 ±â€Š0.8 mM (P < 0.01), and base excess 1.1 ±â€Š2.2 to -3.6 ±â€Š1.7 mM (P < 0.05). Invasive organ-specific monitoring confirmed reduced tissue oxygen delivery; oxygen tension decreased and lactate increased in all tissues, but moderately in brain. Blood volume replacement with PlasmaLyte® improved primary outcome measures toward baseline, confirmed by organ-specific measures, despite hemoglobin reduced from baseline 10.8 ±â€Š1.2 to 5.9 ±â€Š1.1 g/dL post-resuscitation (P < 0.01). CONCLUSION: Non-invasive measures of tissue oxygen delivery and oxygen debt repayment are suitable outcomes to inform Patient Blood Management of hemorrhagic shock, translatable for pre-clinical assessment of novel resuscitation strategies.