Specificity: Anti-CD1a labels Langerhans cell histiocytosis (Histiocytosis X), extranodal histiocytic sarcoma, a subset of T-lymphoblastic lymphoma/leukemia, and interdigitating dendritic cell sarcoma of the lymph node. Immunogen: Human thymus cells (O10); Recombinant human CD1a protein (C1A/711)