Reduced proplatelet production by QITP antibodies in the presence of quinine. CD34+ cells were cultured for 5-6 days, and then seeded for treatment with QITP sera plus Qn or with controls (QITP sera − Qn or NS + Qn) and analyzed after 5 or 6 days in culture. (A) Representative image of typical morphologic features of proplatelets taken with a Leica DMIRB inverted microscope (20× objective using a DC200 camera; Leica). Areas containing proplatelets are circled, with proplatelet-bearing Mks indicated by arrows and proplatelet extensions indicated by white arrowheads (see inset for representative features of proplatelets). Bar indicates 50 μm. The images were cropped and revised using Adobe Photoshop CS5. (B) Proplatelets were enumerated and are presented as the number of proplatelets ± SD per 104 cells. Treatment with QITP sera + Qn significantly reduced proplatelet production.
