Expression of functional neurohypophysial peptide receptors by murine immature and cytotoxic T-cell lines

In order to demonstrate the cryptocrine model of neuroendocrine-immune interactions, specific neurohypophysial (NHP) receptors were detected on murine immature pre-T and cytotoxic T cell lines. A computer analysis (LIGAND) revealed the heterogeneity of the binding sites. The Kd of Highest affinity were equivalent in both cell lines (0.15 nM), but the capacity (Bmax) of both low and high affinity sites was higher in the immature thymic lymphoma-derived pre-T-cell line. The functionality of these receptors was evidenced by their transduction of NHP-related ligands as an increase in intracellular inositol phosphates. These transductory properties were inhibited by a V1 receptor antagonist in pre-T cells, and by an oxytocin (OT) receptor antagonist in cytotoxic T cells. This work supports the involvement of NHP-related ligands and receptors in a process of cryptocrine signaling in the thymus, where the peptide concentration and the receptor affinity are in appropriate concordance.