Detection and quantification of apocrine secreted odor-binding protein on intact human axillary skin

A proposed mechanism of axillary malodor formation is bacterial interaction with secreted odor carrier proteins leading to the release of volatile odor molecules. One primary volatile odor molecule, 3-methyl-2-hexenoic acid, is secreted into the apocrine glandular lumen bound to two carrier proteins known as apocrine secretion odor-binding proteins (ASOB1 and ASOB2). The objective of this study was to develop a biologic method to detect and quantify ASOB2 in vitro and on intact axillary skin. The proteins present in pure apocrine secretion were separated via SDS-polyacrylamide gel electrophoresis (PAGE), electro-blotted, and reacted with antibodies to detect ASOB2. The results of this study demonstrate that ASOB2 shares immunologically homologous epitopes with the human serum protein, apolipoprotein-D (apo-D). Axillary secretions and baseline microflora were collected from two groups of panelists 6 h after showering with a non-antibacterial soap. The extracts were fractionated by SDS-PAGE. ASOB2 was detected selectively by Western blot using a monoclonal mouse-antihuman apo-D antibody and quantified on human axillary skin using the presented methods. Axillary ASOB2 concentration varied among individuals (<0.1-4.1 microg cm(-2)) with significant differences (P < 0.05, anova) seen between those of Chinese descent and non-Chinese descent. Panelists of Chinese ancestry did not show significantly lower baseline microflora levels when compared to non-Chinese panelists.