Elevated levels of soluble interleukin-2 receptors in multiple sclerosis

The expansion of activated, antigen-reactive T-cell populations is dependent on the sequential induction and expression of interleukin-2 (T-cell growth factor) and the interleukin-2 receptor, and the subsequent binding of interleukin-2 to its high-affinity membrane receptor. In a letter in the May 5 issue,Trotter and colleagues have shown elevated serum levels of interleukin-2 in patients with chronic progressive multiple sclerosis. Our studies show an elevation in the serum level of the released form of the interleukin-2 receptor Tac peptide in chronic progressive multiple sclerosis. Taken in conjunction with the findings of elevated serum interleukin-2 by Trotter et al. and others, and the evidence of the elevated or prolonged expression of membrane-bound interleukin-2 receptor, the increased soluble interleukin-2 receptor extends the notion that an activated cellular immune state parallels the evolution of the demyelinating pathologic process in multiple sclerosis. Further sampling during acute exacerbations will determine the usefulness of soluble interleukin-2 receptor in monitoring disease progression and response to therapy.