Expression of IL-11 receptor α chain in human platelets. (A) Total RNA from human platelets, K562 cells, and HEL cells was isolated and analyzed via RT-PCR as described in Fig 4. The DNA fragments were visualized by including digoxigenin-11-dUTP in the PCR mix and using an immunochemiluminescent detection system. Autoradiography of the membrane filter was performed for 2 hours. The primers used generated the fragments described in Fig 4: human IL-11R (lanes 1, 2, and 4) and human c-mpl (lanes 3 and 5). Lane 1, no cDNA; lanes 2 and 3, platelet cDNA from 1 × 10⁶ cell equivalents; lane 4, K562 cDNA from 37.5 ng of polyA⁺ RNA; lane 5, HEL cDNA from 37.5 ng of polyA⁺ RNA. (B) Western blot analysis of IL-11 receptor α chain expression in human platelets. Total protein from platelets (7.5 × 10⁷ for IL-11R and 5 × 10⁷ for CD41) and cells (5 × 10³ CHO cells, 5 × 10³ CHO/IL-11R cells, and 2 × 10⁶ K562 cells) was separated by SDS-PAGE and transferred to nitrocellulose membranes. IL-11 receptor α chain (lanes 1 through 4) and CD41 (lanes 5 and 6) were detected with 1.0 μg/mL of primary antibody. Autoradiography was performed on the membranes (CD41 for 30 seconds and IL-11 receptor for 1 hour).