Chemicalinvestigationsofmhcodortype in Other Species

CHEMICALINVESTIGATIONSOFMHCODORTYPE IN OTHER SPECIES

(a) Rats

Janssen and colleagues (2001) injected recombinant soluble MHC class I moleculesintravenously into male Lewis test rats and monitored the urinary volatile profiles.No qualitative, but rather quantitative differences were observed in the animalstreated 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.

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 profileswas 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 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 volatilecompounds.

Pennet 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 HLA-related compound was identified in this study. Instead, 44 individual and 12 gender-associated 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(Gallagheret 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 vitroto test the hypothesis that 3-methylbutanal is produced from the culture and that its productionis 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 thatthe interaction of HLA and skin microflora may influence 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 humans.Genetica104, 265-273. (10.1023/A:1026431303879)

Gallagher, M., Wysocki, C. J., Leyden, J. J., Spielman, A. I, Sun, X. & Preti G. 2008 Analyses of volatile organic compounds from human skin.Br. J. Dermatol.159, 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)

Kuhn, F. & Natsch, A. 2009 Body odour of monozygotic human twins: a common pattern of odorant carboxylic acids released by a bacterial aminoacylase from axilla secretions contributing to an inherited body odour type.J. R. Soc. Interface6, 377-392. (doi:10.1098/rsif.2008.0223)

Penn, D.J., Oberzaucher, E., Grammer, K., Fischer, G., Soini, H.A., Wiesler, D., Novotny, M.V., Dixon, S.J., Xu, Y. & Brereton, R.G. 2007 Individual and gender fingerprints in human body odour. J. R. Soc. Interface4, 331-340. (doi:10.1098/rsif.2006.0182)

Savelev, S. U., Antony-Babu, S., Roberts, S. C., Wang, H., Clare, A. S., Gosling, L. M., Petrie, M., Goodfellow, M., O'Donnell, A. G. & Ward, A. C. 2008 Individual variation in 3-methylbutanal: a putative link between human leukocyte antigen and skin microflora.J. Chem. Ecol.34, 1253-1257.(doi:10.1007/s10886-008-9524-1)

Sommerville, B. A., Wobst, B., McCormick, J. P., Eggert, F., Zavazava, N. & Broom, D. M. 1995 Volatile identity signals in human axillary sweat: the possibleinfluence of MHC class I genes. InChemical signals in vertebrates VII,(eds R. Apfelbach D. Müller-Schwarze), pp. 535–538.Oxford: Pergamon Press.