Highly glycosylated Hp and lactoferrin colocalize in subcellular fractions enriched in specific granules. Subcellular fractions were isolated from purified peripheral-blood neutrophils and assayed by ELISA and Western blot analysis. Lines indicate subcellular fractions containing relative concentrations for MPO (marker for azurophil granules, peak concentration in fraction 5-433 μg/mL), Lf (marker for specific granules, peak concentration fraction 11-187 μg/mL), Gel (marker for gelatinase granules, peak concentration in fraction 16-33 μg/mL), and Alb (marker for secretory vesicles, peak concentration in fraction 21-2.2 μg/mL). Two forms of Hp were detected by Western blot analysis, an abundant form with a highly glycosylated β-chain of approximately 45 to 65 kDa that colocalized in fractions with high content of the specific granule protein Lf (fractions 10-15) and a scarce form with a β-chain of 39 kDa that colocalized in fractions containing Alb (fractions19-23), a protein endocytosed from plasma and stored in secretory vesicles of neutrophils.