High Proportion of PNH Type II Neutrophils Is Associated With Thrombosis in Patients Displaying a PNH Clone ≥ 1

The clinical significance of PNH Type II white blood cells (WBCs) remains unclear. We assessed the relative percentage (rel%) of Type II neutrophils in 355 patients with a PNH clone clone: To make copies. Bone marrow stem cells clone themselves all the time. The cloned stem cells eventually become mature blood cells that leave the bone marrow and enter the bloodstream. ≥ 1% on neutrophils enrolled by 33 flow cytometry flow cytometry: (sy-TOM-uh-tree) A laboratory test that gives information about cells, such as size, shape, and percentage of live cells. Flow cytometry is the test doctors use to see if there are any proteins missing from the surface of blood cells. It is the standard test for confirming a diagnosis of paroxysmal… laboratories in the 5-year French nation-wide multicenter prospective observational study. We first analyzed 127 of 133 patients with a major PNH clone (≥ 50%) and evaluable Type II neutrophil neutrophil: (NOO-truh-fil) The most numerous of the white blood cells, important for helping the body fight infections (particularly bacterial and fungal infections. rel%. Using hemolysis hemolysis: (hi-MOL-uh-suss) The destruction of red blood cells. data available for 107 patients, a threshold of 3% Type II neutrophils rel% distinguished two groups: 22 "high Type II" and 105 "low Type II" patients. Hemolysis was less frequent in the "high Type II" group. Thrombosis Thrombosis: (throm-BOE-suss) A blood clot (thrombus) that develops and attaches to a blood vessel. was more frequent at diagnosis and during cumulative long-term follow-up in this group. High neutrophil rel% ≥ 3% was independently associated with thrombotic events. Among 222 patients with smaller PNH clones (1%-50%), 207 displayed evaluable Type II neutrophil rel%, of which 87 were classified as "high Type II" and 120 as "low Type II". Although no thrombosis was present at diagnosis, two thrombotic events occurred during follow-up in the "high Type II" group, whereas none were observed in the "low Type II" group. Long-term follow-up showed no major changes in Type II neutrophil rel%, irrespective of variations in total clone size. These findings suggest that, regardless of the total PNH clone size, PNH Type II neutrophil rel% is a stable parameter and may represent a reliable predictor of thrombosis, potentially supporting earlier consideration of anticomplement therapy initiation.