The major histocompatibility complex and the chemosensory signalling of individuality in humans.

The chemosensory identity of mice and rats is determined partly by polymorphic genes of the major histocompatibility complex (MHC). In inbred strains of mice, as well as in seminatural populations, MHC-associated mating preferences selectively influence reproductive success, thus serving to promote heterozygocity in the MHC. In order to determine whether MHC-associated chemosignals are present in humans, two studies were conducted. In a first study, olfactory identification of MHC-associated chemosignals was conducted on 12 trained rats' responses to the urine odors of humans. In a second study, MHC-associated olfactory cues in humans were analyzed by means of gas chromatography. The results indicate that the urine odors of humans are associated with the MHC and demonstrate that the profile of volatile components in the urine odors shows some association with the MHC. Furthermore, results show that a profile of some specific components, as well as a few ubiquitous volatiles, constitutes MHC-associated odor signals in humans.

Molecular forms of soluble HLA in body fluids: potential determinants of body odor cues.

The major histocompatibility complex (MHC) has been linked to encoding for individual olfactory identity. Experiments in mice and rats proved that behavior and mating were, at least in part, determined by genes within the MHC. This study was aimed at investigating whether sHLA are excreted in human urine, saliva and sweat. In particular examination of the molecular forms in these fluids would give clues to whether break down forms of soluble MHC molecules might participate in shaping behavior. Major bands of 45, 40, and 23 kD were detectable. Increased levels of sHLA were measured using a quantitative ELISA in urine shortly before ovulation decreasing to normal levels thereafter. In animal models strain specific MHC-linked odor cues have been detected in urine. Thus, excretion of sHLA in urine might indicate a similar role for these molecules in humans.

MHC-associated and MHC-independent urinary chemosignals in mice.

The chemosensory identity of mice, rats, and humans is determined partly by polymorphic genes of the major histocompatibility complex (MHC). In inbred strains of mice as well as in seminatural populations MHC-associated mating preferences selectively influence reproductive success. To explore MHC-associated chemosignals in relation to otherwise genetically determined chemosignals a first study was conducted on seven trained rats' responses to the odors of inbred strains of mice. Results of the first study confirmed that neither the MHC nor genes in the genetic background dominate in determining urine odor specificity of mice and that specific olfactory cues associated with either the MHC or the genetic background can be identified by olfaction. In a second study, these specific olfactory cues were analyzed by means of gas chromatography. The results indicate that specific volatile components associated with either the MHC or the genetic background can be found in mouse urine odor, and that profiles of ubiquitous volatile components show some association with either the MHC or the genetic background. Furthermore, results show that a small number of specific compounds as well as a profile of some few ubiquitous volatiles constitute MHC-associated odor cues and that influences of the MHC and genes in the genetic background interact in constituting urine odor specificity in mice.

[Characteristics of changes of personal odor after experimental bone marrow transplantation]. / Charakteristik der Eigengeruchsveränderung nach experimenteller Knochenmarktransplantation.

In an operant conditioning paradigm 4 Balb/c inbred strain mice were conditioned to discriminate between urine samples of two other inbred strains. The purpose was to examine whether or not the known stimulus configuration during training had any effect upon the rate of recognition of other stimuli. On the basis of this procedure, we subsequently investigated the extent to which an allogeneic bone marrow transplantation interferes with the olfactory identity of an individual. For the transplants a strain was inbred which had no contact to the animals tested, a procedure used for the first time here. Furthermore, also for the first time, it was possible to demonstrate in a direct comparison, the role played by donor versus recipient characteristics on the olfactory composition of the recipients odor.

[Exchange of the hematopoietic system changes chemosensory identity]. / Der Austausch des hämatopoetischen Systems verändert die chemosensorische Identität.

It has been shown that the scent of mice changes after a bone marrow transplantation. Previously obtained results were re-examined with a new design that rules out possible avoidance learning effects. Two BALB/c mice, deprived of water for 20 hours each day, were trained in a Y-maze to discriminate two fully allogeneic mice strains (C3H = S+ and C57 = S-) via their urine odor. Reinforcement for correct choice was provided by a drop of water. Urine samples of different fully allogeneic mice strains (C3H, C57 and A/J) and bone marrow transplanted chimeras (C57----C3H and C3H----C57) were submitted to different "transfer of training" -tests. In the conditioning paradigm used, the animals learn to identify S+ and also do not avoid S- after the training. The urine odor of the C57----C3H-chimeras was found to be different from the strain-specific urine odor of C3H animals. Since this change could not be found in syngeneic transplanted chimeras, it is concluded that it is caused by the graft. The experiments failed, however to demonstrate that the urine odor of allogeneic chimeras is constituted solely by donor- and recipient-specific components.

Changes in strain-specific urine odors of mice due to bone marrow transplantations.

The change in strain-specific urine odors which appears after bone marrow transplantations was systematically examined in mice in order to demonstrate an influence of the hematopoietic system on urinary chemo-signals. Four mice were trained in a Y maze to discriminate two fully allogeneic mouse strains via their urine odors. Urine samples obtained from three inbred strains, from syngeneic reconstituted mice, and from allogeneic reconstituted chimeras were combined in a number of 'transfer of training' tests. The strain-specific urine odors of the recipients were changed by a fully allogeneic bone marrow transplant. Since this change could not be found in syngeneic reconstituted mice, we concluded that it was caused by the graft. Experiments partly failed to demonstrate donor- and recipient-specific components in the urine odor of the chimeras.