Taurine and proliferation of lymphocytes in physically restrained rats

BACKGROUND: Taurine is present in lymphocytes and seems to modulate certain immune cell functions. Among the effects of taurine on these cells are protection against antioxidants and regulation of inflammatory aspects of the immune response. Stress affects antigen presentation, traffic and proliferation of leukocytes, as well as antibody and cytokine secretion. The purposes of this study were to explore the possible direct effects of taurine concentrations on lymphoproliferation and interleukins levels in control and in physical restrained rats. METHODS: Lymphocytes of male Sprague-Dawley rats, stressed by physical restrain and controls (5 h per day for 5 days) were isolated from blood by Histopaque (1077 g/l) and differential adhesion to plastic, and then cultured (72 h) in the presence of different concentrations of taurine (0.5 – 50 mM), β-alanine (0.5 – 50 mM), or both, without or with the T cells mitogen, concanavalin A. Plasma and lymphocytes levels of pro-inflammatory interleukin-1β and anti-inflammatory interleukin-10 were respectively measured by Pierce Endogen rat ELISA Kits. Taurine in plasma and in lymphocytes were determined by HPLC. RESULTS: Lymphoproliferation of resting cells significantly decreased in the presence of 3 and 6 mM taurine and increased up to control level at 12 mM taurine. In concanavalin A-activated lymphocytes, the effect of taurine was greater. β-alanine increased lymphoproliferation in a bell shaped dose-dependent manner and decreased it in activated lymphocytes but in a lower magnitude. In combination, β-alanine impaired the effect of taurine at 3 and 6 mM. After restriction, no change in lymphoproliferation was observed at different concentrations of the amino acids without or with concanavalin A, although pro-inflammatory interleukin and taurine in plasma and in lymphocytes significantly increased. CONCLUSIONS: Taurine affects lymphoproliferation in control rats, following a dose-dependent manner, an effect that might involve its transport into the cells. Elevation of interleukin-1β produced in stressed rats by physical restrain could seriously affect the immune balance, whereas taurine increase might be protective. These results suggest that taurine and taurine transport play a role in lymphoproliferation. In addition, modifications of taurine system in lymphocytes take place during restriction stress.