Immunohistochemical localization of PF4.

Spleens were stained with the monoclonal anti-PF4 RTO as the primary antibody. Each spleen was counterstained with hemotoxylin. Panel A represents immunohistochemical studies of the spleen from a wild-type mouse, whereas panel B is from a 10 copy PF4-Only mouse, and panel C is from a 21 copy λ-PBP/PF4 mouse. The arrows point to some, but not all, of the megakaryocytes in each field. Original magnification 20 ×.