Chromosomally clonal T cells in the skin, blood, or lymph nodes of two Sezary syndrome patients express CD45RA, CD45RO, CDw150, and interleukin-4, but no interleukin-2 or interferon-gamma

Cutaneous T cell lymphomas are considered to represent a clonal malignancy of mature T lymphocytes of the T helper memory subtype. A method enabling t he direct identification of clonal malignant cells in tissue and, at the sa me time, identification of the surface molecules they express has not been available, however. We have developed an application of the FICTION techniq ue (simultaneous fluorescence immunophenotyping and interphase cytogenetics ) to be used on fresh blood, skin, and lymph node samples. A prerequisite f or this method is the characterization of a moleculocytogenetic clone in or der to select the proper probes. With this method, we demonstrate that the true malignant cells express CD3, CD4, and CD45RO in the blood, skin, and l ymph nodes of two Sezary syndrome patients. The majority of these cells exp ress also CD45RA (albeit of varying intensity) and CDw150, The cytokine exp ression pattern of the clonal cells in skin and lymph nodes was interleukin -2 and interferon-gamma negative and interleukin-4 positive. Interleukin-10 expression varied, The malignant cells did not express granzyme B, thus in dicating that they do not have cytotoxic properties. Clonal cells with the same constant phenotype could be found even in lymph nodes with not yet mor phologically identifiable malignant cells. This is the first report of the FICTION method applied directly on skin tissue. With this method we demonst rated that the chromosomally clonal cells in these two cases of Sezary synd rome could be intermediate forms between naive CD45RA+ and CD45RO+ Th2 cell s.