Flow cytometry analysis of platelet GPs.

Tracings of flow cytometry with mAbs against GPIIb/IIIa, GPIbα (SZ2 and MB45, the conformational-dependent and -independent mAb, respectively), GPIX, and GPV of 3 patients, each representative of a distinct group. At the genotype level patient A carries the Bolzano mutation, whereas patients B and C do not have the mutation. In each patient (white curve), the expression of GPIIb/IIIa on the platelet surface was increased compared to that of the healthy control (gray curve), as shown by shifting of the curves to the right. In contrast, single components of the GPIb/IX/V complex were variously reduced in patients A and B. These patients have a GP profile consistent with a heterozygous BSS phenotype. Of particular interest is the different fluorescence obtained with SZ2 and MB45 mAbs in the Bolzano patient, suggesting the presence of a conformationally changed GPIbα protein. Patient C shows a clear increase of all GP because of the larger volume of platelets and thus represents the “true” thrombocytopenia- affected patient.