Localization of HBP in neutrophil subcellular fractions.

Human neutrophils were fractionated in a flotation gradient as described in “Materials and methods.” Localization of neutrophil organelles in the gradient is shown by marker analysis of the fractions. (A) Nonlatent alkaline phosphatase (activity measured in the absence of detergent; marker for the plasma membrane; open circles), latent alkaline phosphatase (difference between activity measured in the presence and absence of detergent; marker for the secretory vesicles; closed circles), gelatinase (densitometric curve from panel B; squares), and MPO (densitometric curve from panel C; triangles). (B, C) Western blots of the fractions probed with antibodies to gelatinase and MPO, respectively. (D) Presence of HBP in the gradient is shown as a densitometric curve measured from the immunoblot (E) probed with anti-HBP antibodies.