Expression of a common secretory granule specific protein as a marker for the extracellular organelles (prostasomes) in human semen.
OBJECTIVE
To further characterize prostasomes, trilamellar to multilamellar vesicles that are thought to originate from acinar cells of the human prostate and present in appreciable amounts in normal human semen. Purified prostasomes were shown to have immunosuppressive activity in vitro as measured by inhibition of mitogen-induced lymphocyte proliferation and inhibition of superoxide generation by neutrophils. A granule membrane protein, called granulophysin, has recently been identified in the membranes of platelet dense granules. Antibodies that recognize granulophysin also stain granules in different cell types including leukocytes, melanocytes, neurones, endothelial cells, and epithelial cells.


METHODS
The presence of epitopes recognized by antigranulophysin monoclonal antibody in prostasomes was investigated using indirect immunofluorescence and subsequent cytofluorimetric analysis. The protein was also analyzed by Western blotting. Reactivity of antigranulophysin antibody with the prostate tissue was studied by immunoperoxidase staining.


RESULTS
A majority of prostasome particles specifically reacted with antigranulophysin antibody. In lysates prepared from prostasomes, a broad band of 32 to 37 kd was detected by Western blotting.


CONCLUSIONS
This report defines granulophysin as a constituent membrane molecule of prostasomes that may serve as a useful marker in elucidation of prostasome function.
Skibinski
G
G
Department of Surgery, University of Edinburgh Medical School, Scotland.
Kelly
R W
RW
James
K
K
D015703:Antigens, CD / Q000032:analysis*; D015153:Blotting, Western; D003594:Cytoplasmic Granules / Q000737:chemistry*; D005110:Extracellular Space / Q000737:chemistry*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D010980:Platelet Membrane Glycoproteins / Q000032:analysis*; D012661:Semen / Q000737:chemistry*; D060149:Tetraspanin 30
D015703:Antigens, CD; C554586:CD63 protein, human; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30