Mitogenic response and steroid sensitivity in MS lymphocytes

OBJECTIVES: We investigated mitogenic response and steroid sensitivity in multiple sclerosis (MS) lymphocytes to establish if MS lymphocytes were less steroid responsive. MATERIAL AND METHODS: We compared mitogenic response to phytohaemagglutinin (PHA) and inhibition by dexamethasone (DEX) in circulating lymphocytes from both MS patients and healthy subjects. RESULTS: We found a range of responses in each group but no significant differences between the two groups, nor in patients with and without enhancement on magnetic resonance imaging. The mid-inhibitory concentration of DEX in response to 1 microg/ml PHA was significantly lower than that for 2.5 microg/ml PHA in the patients. The mid-inhibitory concentrations of DEX in response to 2.5 microg/ml PHA negatively correlated with endogenous serum cortisol concentrations. CONCLUSION: These data imply a spectrum of glucocorticoid response that is similar in normal and MS lymphocytes and can partly explain why response to steroid therapy is variable.