Genes involved in platelet aggregation and activation are downregulated during acute anaphylaxis in humans.

Objective: Mechanisms underlying the anaphylactic reaction in humans are not fully understood. Here, we aimed at improving our understanding of anaphylaxis by investigating gene expression changes.

Methods: Microarray data set GSE69063 was analysed, describing emergency department (ED) patients with severe anaphylaxis ( = 12), moderate anaphylaxis ( = 6), sepsis ( = 20) and trauma ( = 11). Samples were taken at ED presentation (T0) and 1 h later (T1). Healthy controls were age and sex matched to ED patient groups. Gene expression changes were determined using , and pathway analysis applied. Differentially expressed genes were validated in an independent cohort of anaphylaxis patients ( = 31) and matched healthy controls ( = 10), using quantitative reverse transcription-polymerase chain reaction.

Results: Platelet aggregation was dysregulated in severe anaphylaxis at T0, but not in moderate anaphylaxis, sepsis or trauma. Dysregulation was not observed in patients who received adrenaline before T0. Seven genes ( (adjusted value = 5.57 × 10), (adjusted value = 9.40 × 10), (adjusted -value = 2.15 × 10), (adjusted -value = 2.29 × 10), (adjusted -value = 1.20 × 10), (adjusted -value = 1.39 × 10) and (adjusted -value = 4.06 × 10)) were significantly downregulated in severe anaphylaxis patients who did not receive adrenaline before ED arrival, compared with healthy controls. One gene ( (adjusted -value = 1.29 × 10)) was significantly downregulated in moderate anaphylaxis patients who did not receive adrenaline before ED arrival, compared with healthy controls.

Conclusion: Downregulation of genes involved in platelet aggregation and activation is a unique feature of the early anaphylactic reaction not previously reported and may be associated with reaction severity.