The importance of the nurse cells and regulatory cells in the control of T lymphocyte responses.

T lymphocytes from the immune system are bone marrow-derived cells whose development and activities are carefully supervised by two sets of accessory cells. In the thymus, the immature young T lymphocytes are engulfed by epithelial "nurse cells" and retained in vacuoles, where most of them (95%) are negatively selected and removed when they have an incomplete development or express high affinity autoreactive receptors. The mature T lymphocytes that survive to this selection process leave the thymus and are controlled in the periphery by another subpopulation of accessory cells called "regulatory cells," which reduce any excessive immune response and the risk of collateral injuries to healthy tissues. By different times and procedures, nurse cells and regulatory cells control both the development and the functions of T lymphocyte subpopulations. Disorders in the T lymphocytes development and migration have been observed in some parasitic diseases, which disrupt the thymic microenvironment of nurse cells. In other cases, parasites stimulate rather than depress the functions of regulatory T cells decreasing T-mediated host damages. This paper is a short review regarding some features of these accessory cells and their main interactions with T immature and mature lymphocytes. The modulatory role that neurotransmitters and hormones play in these interactions is also revised.

A neurotransmitter system that regulates macrophage pro-inflammatory functions.

Neurotransmitters released through peripheral and autonomic nerves play an important role in the signaling from the cells of the nervous system to lymphocytes, macrophages and other cells of the immune system. Macrophages are related to numerous physiological and pathological inflammatory processes since their cytokines play an important role in the defensive responses against invasive microorganisms, atherosclerosis progress, insulin resistance, behavior deviation, hematopoiesis feedback, degenerative chronic diseases and the stimulation of the hypothalamus-hypophysis-adrenal axis. Production of pro-inflammatory cytokines by macrophages is the main target for the modulatory activity of diverse neurotransmitters. In this brief review, we show how some neurotransmitters released by the central or the autonomic nervous systems down-regulate peripheral macrophages' inflammatory functions to balance immune protective mechanisms, although they can also promote the collateral progress of diverse diseases. The possible therapeutic uses of some neurotransmitters and the agonists or antagonist of their respective receptors are included as well.

GABA (A) receptor subunits RNA expression in mice peritoneal macrophages modulate their IL-6/IL-12 production.

The expression and functionality of the gamma aminobutyric acid A receptor (GABA(A)R) in mice macrophages was explored. Reverse Transcriptase-Polymerase Chain Reaction showed that macrophages express the GABA(A)R RNA for the alpha1, alpha2, beta3 and delta subunits, but not for the alpha5, beta1, beta2 and gamma3 subunits. The expression of alpha1 subunit was also revealed by confocal microscopy. LPS-stimulated macrophages significantly reduced their in vitro production of IL-6 and IL-12 after GABA adding to the culture medium. These results showed that BALB/c mice peritoneal macrophages express a functional subset of GABA(A)R subunits.