Anti-V region antibodies as "almost clonotypic" reagents for the study of cutaneous T cell lymphomas and leukemias.

Despite recent advances in the understanding of normal T lymphocyte immunobiology, there has been little progress in characterizing the non-HTLV cutaneous T-cell lymphomas and leukemias (CTCL) Mycosis Fungoides and Sezary syndrome. The two major impediments to in vitro studies of these malignancies have been the contamination of CTCL cells with normal T cells and the inability to induce a vigorous proliferative response or establish long-term cultures with standard T-cell mitogens. The ideal reagent for identifying CTCL cells in a given patient would be tumor specific. Although a monoclonal antibody to the clonotypic antigen receptor on CTCL cells would approach this ideal, it is not currently feasible to generate such antibodies for each CTCL patient. As a compromise, we chose to test an "almost clonotypic" reagent by examining whether monoclonal antibodies directed at the variable (V) region of the T-cell antigen receptor could be applied to CTCL. We identified three Sezary patients, who by standard T-cell phenotype and Southern blot analysis for clonality had a virtually pure peripheral blood population of leukemic cells (PBL). We then screened the PBL of these patients with a panel of seven commercially available monoclonal anti-V region antibodies and found one patients' cells reacted greater than 99% with alpha V beta 5. The other patients' cells were non-reactive. In addition, we utilized a solid-phase system to cross-link V beta 5 on the one CTCL patients' PBL cells, and found that they proliferated vigorously in the presence of 10 units of IL-2 and IL-4. Parallel cultures have been maintained for one month by restimulation twice a week. These findings suggest that anti-V region antibodies should prove useful for investigating the immunobiology of CTCL.