Soluble CD4 and CD8 in the peripheral blood of patients with multiple sclerosis and HTLV-1-associated myelopathy.

We evaluated the presence of soluble (s) CD4 and sCD8, released from activated T cells, in the sera of patients with multiple sclerosis (MS) and human T lymphotropic virus type 1 (HTLV-1)-associated myelopathy (HAM) using an enzyme-linked immunosorbent assay (ELISA). In addition, peripheral blood T cell subsets in patients with MS and HAM were analyzed by single and two color flow cytometry. The serum level of sCD8 was significantly elevated in MS patients as compared with controls (p less than 0.001). Sera from patients with an exacerbation of acute relapsing MS showed a higher sCD8 level than the patients in remission or controls (p less than 0.01 and p less than 0.001, respectively). The serum levels of both sCD4 and sCD8 were also significantly elevated in patients with HAM (p less than 0.001 and p less than 0.001, respectively). In addition, a significantly increased serum level of soluble interleukin-2 receptor (sIL-2R) was found in patients with HAM as compared with that of controls (p less than 0.001). These observations suggest that CD8 cells may be activated in the peripheral blood of patients with MS and sCD8 may be related to clinical activity, but that both CD4 and CD8 cells may be activated in the peripheral blood of patients with HAM.