CHEMICAL INVESTIGATIONS OF MHC ODORTYPE IN OTHER SPECIES
(a) Rats
Janssen and colleagues (2001) injected recombinant soluble MHC class I molecules
intravenously into male Lewis test rats and monitored the urinary volatile profiles. No
qualitative, but rather quantitative differences were observed in the animals treated with
different recombinant MHC molecules. Four out of 33 peaks detected in GC/MS varied
significantly. Two of them were tentatively identified as nitrogen-containing compounds.
(b) Primates
Knapp et al. (2006) analyzed tail and brachial gland samples collected from 6 MHC-typed
male ring-tailed lemurs (Lemur catta). They observed that the concentration of hexanoic
acid extracted from the tail samples was higher in the lemurs who had a certain MHC
allele than in those who did not have the allele. Due to the small sample size, the
statistical significance of this observation could not be tested.
(c) Humans
Sommerville and colleagues (1995) investigated whether there is an association between
human MHC type (called human leukocyte antigen [HLA]) and sweat volatile profiles. The
HLA-typed odor donors consisted of 3 identical twins and 4 unrelated individuals. The
volatile patterns of the twins were better matched than those of the unrelated individuals
but no association between HLA and sweat volatile profiles was observed.
Eggert et al. (1999) analyzed 3 sets of pooled human urines. Each pool consisted
of urine samples collected from 8 HLA-typed individuals. Two pools shared the A1 and
B8 alleles, while the other had the A3 and B7 alleles. While the authors reported peaks
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with qualitative, as well as quantitative differences between the A1B8 pool and the A3B7
pool, the small sample size (N=3) did not permit valid tests of statistical significance.
They did not identify any of the volatile compounds.
Penn et al. (2007) investigated volatile profiles of urine, saliva and axillary sweat
collected from 197 HLA-typed subjects from a village in the Austrian Alps. No HLArelated compound was identified in this study. Instead, 44 individual and 12 genderassociated compounds were identified out of 373 peaks reproducibly detected from the
sweat samples. However, most of the individual-associated compounds were almost
certainly derived from personal care products such as fragrances, cosmetics and
sunscreens (Gallagher et al. 2008; Kuhn & Natsch 2009). The qualitative differences they
identified between individuals most likely indicate differences in personal preferences for
hygiene products.
Savelev and colleagues (2008) hypothesized that skin microorganisms in the
axillary area may break down HLA fragments and produce individual-specific odor
metabolites. They analyzed the underarm volatiles collected from 18 subjects using
SPME followed by GC/MS analyses. The authors observed that 3-methylbutanal varied
significantly between subjects, whereas within-subject variation over the 3 week
collection period was small and insignificant. They then incubated microflora collected
from the subjects and cultured them in media containing synthesized HLA class I
peptides in vitro to test the hypothesis that 3-methylbutanal is produced from the culture
and that its production is consistent with the in vivo result. Higher production of the
compound was observed in the cultures containing the microorganisms derived from the
subjects who produced larger amounts of 3-methylbutanal in their underarms. The
authors suggested that the interaction of HLA and skin microflora may influence
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individual body odor. However, as the authors acknowledge, whether its production is
specific to certain HLA peptides is not clear.
REFERENCES
Eggert, F., Luszyk, D., Haberkorn, K., Wobst, B., Vostrowsky, O., Westphal, E.,
Bestmann, H. J., Müller-Ruchholtz, W. & Ferstl, R. 1999 The major
histocompatibility complex and the chemosensory signalling of individuality in
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780-791. (doi:10.1111/j.1365-2133.2008.08748.x)
Janssen, E., Göhlen, B., Behrens, D., Richter, K. & Zavazava, N. 2001 Allogeneic
recombinant soluble MHC class I molecules modify urinary odor cues in rats.
Physiol. Behav. 72, 107-114. (doi:10.1016/S0031-9384(00)00389-9)
Knapp, L. A., Robson, J. & Waterhouse, J. S. 2006 Olfactory signals and the MHC: a
review and a case study in Lemur catta. Am. J. Primatol. 68, 568-584.
(10.1002/ajp.20253)
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Petrie, M., Goodfellow, M., O'Donnell, A. G. & Ward, A. C. 2008 Individual
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