A Novel Disulfide-Linked Cell Surface Molecule Present on Resting and Activated Human T Lymphocytes

Abstract

Human T cell leukemias provide an excellent source of homogeneous material to study T cell surface molecules. The monoclonal nature of these malignant cells provides a convenient means to dissect the functional and structural basis of surface antigens present on T cell subpopulations. Using the leukemic OKT4-positive T cells of a patient with Sezary syndrome, we have developed a monoclonal antibody (mAb), termed S152, that reacts with the leukemic cells and a subpopulation of circulating T cells. The antigen recognized by this mAb is detected at a low intensity on circulating T cells and not on T cell lines. When cells are stimulated with mitogens, the intensity of staining by S 152 increases several fold over that seen on resting T cells. The initial characterization of the antigen detected by this mAb reveals it to be a disulfide-linked dimer with two chains of similar or identical molecular weight. Disulfide-linked molecules on the T cell surface have been shown to be limited to very few molecules (1). These molecules, such as the T cell receptor (2,3), transfer-rin receptor (4,5), and 4F2 (6), all appear to be involved in early T cell activation (7). Thus not only is the molecule defined by S152 a member of a rare molecular species but also its relationship to activation suggests that this molecule may play a functional role in T cell proliferation.