1Gamal El-Saeid Eid and 2Fahad J Al-Shammary
1Microbiology and Immunology Unit, 2Clinical Biochemistry Unit, Department of Clinical Laboratory Sciences, College of Applied Medical Science, King Saud University, Riyadh.
Mononuclear immune cells were separated from whole peripheral blood samples obtained from 75 male and female volunteers of different age groups. The cells were in vitro stimulated with PHA-mitogen at different concentrations (0, 2.5, 5.0 and 10 mg/ml). The effect of different concentrations of melatonin (0, 10-7, 10-6, 10-4 and 10-3 M) on the PHA- stimulated cells was studied through ELISA measurements of IL-2 and IFN-g production. The results indicated that the effect of melatonin on PHA-stimulated cells is dose dependent, with a concentration of melatonin of 10-7 to 10-6 M to induce the highest IL-2 and IFN-g production levels from both PHA-treated and non-treated cells. Furthermore, the activity of melatonin was reduced by increasing its dose, where the highest concentration of melatonin (10-3 M) induced significant reduction of IL-2 and IFN-g production levels from cells of all sex and age groups. The highest IL-2 production levels were detected at 10-7 M concentration of melatonin, especially with cells isolated from young males and young females. In contrast, the highest production levels of IFN-g were detected with cells isolated form old males and old females when compared with young groups. The results revealed that melatonin effect could be age-related and support the suggestion that melatonin modulate the physiological activities through Th-1 cells, the producers of the cytokines IL-2 and IFN-g.