Lack of Evidence for HLA-Linked Patterns of Odorous Carboxylic Acids Released from Glutamine Conjugates Secreted in the Human Axilla

Genetic factors within the major histocompatibility locus (MHC) have been shown to influence body odors in mice. MHC-dependent preferences for body odors also have been reported in humans. The axillary glands are a key odor-forming organ in humans, and it is assumed that they provide behaviorally relevant odors. Volatile carboxylic acids are the most diverse class of known axillary odorants, and the pattern of these acids is genetically determined. These acids are released by an N_α-acyl-glutamine-aminoacylase present in skin bacteria. We tested a hypothesis concerning whether or not the inherited individual-specific patterns of odorous acids are strongly influenced by polymorphic genes in the MHC. Axilla secretions were collected in 12 families, comprising 3 to 6 siblings, who had been typed for HLA-A, B, and DRB1 loci. The samples were treated with N_α-acyl-glutamine-aminoacylase, and the methyl esters of the released acids were analyzed with comprehensive two-dimensional gas chromatography (GC × GC) and time-of-flight mass spectrometry (ToF MS). The patterns of the analytes were compared by distance analysis. The distance was lowest between samples taken from the same individual, confirming the presence of donor-specific odor-prints. A much higher distance was observed between siblings, but there were no differences among siblings sharing none, one, or both HLA-A,B,DRB1 haplotypes. By applying principal component analysis, a clear clustering of samples taken from one individual was confirmed, but no clustering was observed for siblings sharing identical HLA-A,B,DRB1 alleles. Thus, the genetically determined pattern of N-acyl-glutamine conjugates of volatile carboxylic acids, secreted in the human axilla, appears not to be determined by genes residing in the HLA complex.