Quantifying reticulated platelets, preplatelets, and barbells in acquired thrombocytopenia. All measurements were performed in trisodium citrate–anticoagulated whole blood. (A) Healthy control (HC; green dots; n = 12) and ITP (red dots; n = 7) blood was incubated at 37°C for 1.5 hours; platelet count, MPV, and IPF were measured by the XN1000 hematology analyzer (Sysmex); and preplatelets and barbells were measured by ISFC with correlations between IPF% and preplatelets and/or barbells. (B) α-Tubulin immunofluorescence imaging of control and ITP platelet-rich plasma displaying preplatelets (yellow arrows), barbells (blue arrows), and elongated preplatelets (purple arrows; n = 3; Leica DM6000 wide-field microscope, ×60 magnification; bars represent 5 μm). (C) Mean diameter of preplatelets and area of barbell platelets measured by ISFC in healthy control blood (n = 15) vs ITP blood (n = 8; bar represents 7 μm). (D) Blood samples were taken from patients with high-grade lymphoma or myeloma before chemotherapy (baseline; day −1), 5-7 days after stem cell autograft (nadir). Platelet counts and IPF were measured by the XN1000 analyzer and preplatelets and barbells by ISFC (n = 6). (A-B,D) Unpaired t-test ±1 standard deviation. (A) Pearson’s correlation coefficient. *P < .05, **P < .01, ***P < .001; ****P < .0001.