Increased CD11b neutrophil expression in Budd–Chiari syndrome or portal vein thrombosis secondary to polycythaemia vera

Summary Budd–Chiari syndrome and portal vein thrombosis (BCS/PVT) are frequently associated with polycythaemia vera (PV). In an attempt to elucidate the mechanisms of BCS/PVT secondary to PV (T‐PV), CD11b neutrophil expression, neutrophil oxidative burst and platelet–neutrophil complexes (PNC) were assessed in 17 such patients. Three groups served as controls: BCS/PVT not secondary to PV (T‐nPV; n = 20), PV without thrombosis (PV‐nT; n = 16), and healthy controls (HC; n = 20). Baseline CD11b expression (in mean fluorescence intensity units) was 101 [95% confidence interval (CI): 79–128] in T‐PV patients, versus 25 (95% CI: 18–35) in T‐nPV, 59 (95% CI: 43–80) in PV‐nT, and 34 (95% CI: 25–48) in HC ( P < 0·001). After N ‐formyl‐ L ‐methionyl‐ L ‐leucyl‐ L ‐phenylalanine activation, T‐PV patients also showed higher CD11b values: 190 (95% CI: 151–238), versus 55 (95% CI: 41–72) in T‐nPV, 111 (95% CI: 81–153) in PV‐nT, and 77 (95% CI: 63–95) in HC ( P < 0·001). In BCS/PVT, CD11b neutrophil expression had 90% specificity and 100% sensitivity for the association with PV. Finally, PV patients had higher oxidative burst and PNC than T‐nPV patients or HC ( P < 0·05). These results support a role for neutrophils in BCS/PVT secondary to PV and indicate that neutrophil CD11b expression could be of use for PV screening in BCS/PVT patients.