[The central role of the thymus in the education of T cells to neuroendocrine principles].

The thymus, the lymphoid organ responsible for the induction of central T cell self-tolerance, is the site of expression of peptides belonging to the neurohypophysial peptide family. The classical model of neurosecretion established by the Scharrers for the hypothalamo-neurohypophysial axis however cannot be applied to characterize the secretory pathways of neurohypophysial-related peptides in the thymic epithelial component. The novel model of cell-to-cell cryptocrine signalling has recently been proposed by J.W. Funder to describe the molecular relationships between fixed epithelial cells and migratory differentiating cells. In the thymus, the cryptocrine signalling is further closely associated to the presentation of the "self" molecular structure by major histocompatibility complex-derived proteins to developing T cells. On the basis of our observations, the model of the thymic repertoire of neuroendocrine "self" antigens transposes to the molecular peptide level the dual physiological role of the thymus in T cell negative and positive selection. Moreover, this model should also contribute to a better understanding of the molecular mechanisms underlying the central T cell tolerance of "self" neuroendocrine functions.