The role of the Major Histocompatibility Complex in the Immunobiology of Self-Aromas

Abstract

The authors present a review of the immunobiological mechanism of olfaction considering current and relevant information about the odors released by vertebrate organisms, and its association with the immune system. Many theories concerning to the type and the quality of the molecular structures of odors or aromas have been proposed, but the most important are the steric theory of odor and the vibration theory of odor. Several techniques based on brain activities have been studied in association with sensorial processes, and they were particularly important to evaluate the physiologycal effects of odors. Molecules of the Major Histocompatibility Complex (MHC) have been identified in individual body odors (odortype), and volatile compounds of the MHC were easily detected in the urine of mice. The major relevant studies related to the Olfactory Receptors (ORs) and the MHC were conducted in mice models, and these studies demonstrated that the odortype has an important role in the partner choice, as well as in the relationship between mothers and their offsprings. A sensorial gas apparatus called “eletronic nose” has been used as an instrument capable of detecting molecules of the MHC in the odortypes. In conclusion, the diversity of self-aromas or odortypes seems to be generated in the context of the MHC, and consequently varies according to the genetic background of the individual. In spite of several controversies among scientists concerning to the immunobiology of the aromas, mostly in human beings, we could hypothesize that similar types of odors could influence the human choice. Future studies are necessary to clarify and confirm these findings in human beings.