In a study published in the journal Blood, Yale scientists identify the molecular triggers that stimulate Cutaneous T Cell Lymphoma (CTCL) cells to clonally expand into large populations of malignant lymphocytes. CTCL is the most common adult malignancy of T lymphocytes, the white blood cells of the immune system. Finding CTCL triggering factors has been a major goal of Richard L. Edelson, M.D., Director of the Yale Cancer Center, and professor and chair of dermatology at Yale, since he and his colleagues at the National Cancer Institute first identified CTCL as a separate category of lymphoma thirty years ago. The Yale research group reported that, like all T cells, the cancerous CTCL cells require antigenic stimuli delivered by specialized dendritic cells of the epidermis, referred to as Langerhans cells (LC), in order to replicate. To determine the nature of the activating antigen, Carole Berger, a research scientist in dermatology set up a physiologic laboratory system mimicking the tight relationship in vivo between CTCL cells and LC. The research team considered three broad categories of antigen as the source of the signal: the protein products of tumor viruses, of mutated genes, and of normal but usually inactive genes. The study reports that CTCL develops from a small subset of lymphocytes that are pre-programmed to respond to self-antigens exposed during normal cell death. As cells undergo the process of apoptosis, cryptic -- or masked -- antigens, are uncovered. Those newly available antigens are presented by LC directly to CTCL receptors, stimulating the malignant cells rapidly divide.
