Prostasomes are organelles secreted by human prostate epithelial cells and appear freely in semen. Most prostasomal functional and biochemical characteristics have been settled on basis of seminal prostasomes (SP).

Three types of prostasomes, viz., from seminal plasma, prostate gland (native), and prostate cancer bone metastasis, were isolated and compared for their biochemical and functional characteristics.

Flow cytometry showed that all three types of prostasomes had a similar size distribution and electrophoresis revealed close similarities in banding pattern. Also, a high cholesterol/phospholipid ratio and some marker enzymes were distinctive common features. The unusual chromogranin B (CgB)/chromogranin A (CgA) ratio with CgB in abundance over CgA, previously found only in SP, was also valid for the native (NP) and metastasis‐derived prostasomes (MP). The latter prostasome type contained a 10‐fold higher amount of CgA compared to the others. SP and MP showed the same promotive effect on sperm forward motility, whereas NP did not. All three prostasome types exhibited an antibacterial activity against Bacillus megaterium.

Since the three prostasome types were isolated from different environments, our data support the view that the common characteristics were prostasome‐genuine. Prostate 54: 322–330, 2003. © 2003 Wiley‐Liss, Inc.