title: Hairy cell leukemia: its place among the chronic B cell leukemias.
abstract: Hairy cell leukemia is a chronic B cell leukemia. The presence of surface Ig (SIg) of gamma or multiple isotypes on the cells locates HCL at a rather mature stage of B cell differentiation. The reactivity of HC with McAb is in accordance with this concept (T65-, OKM1+, FMC7+, BA-1-). To relate HCL to other chronic B cell leukemias, a morphologic classification was developed that distinguishes, besides HCL, five subtypes of chronic B cell leukemia. CLL showed weak staining for SIg of mu +/- delta class. The phenotype with McAb was T65+, OKM1-, FMC7-, BA-1+. Prolymphocytic transformation of CLL had essentially the same membrane phenotype. LPL often had brighter SIg of mu +/- delta class with gamma or multiple isotypes in about half of the cases. McAb gave a T65-or+, OKM1-or+, FMC7-or+, BA-1+ phenotype. The same surface-marker profile was found in CL. Finally, PLL showed bright SIg of gamma or multiple isotypes in the majority of cases and reactivity with McAb according to a T65-or+, OKM1+, FMC7+, BA-1+ pattern. The various immunologic phenotypes of the morphologic subtypes showed a considerable overlap. The various chronic B cell leukemias should be located in the scheme of B cell differentiation in the sequence CLL-LPL/CL-PLL-HCL.
mesh_terms: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000032:analysis*; D001402:B-Lymphocytes / Q000276:immunology; D002908:Chronic Disease; D003937:Diagnosis, Differential; D006801:Humans; D007938:Leukemia / Q000145:classification* / Q000276:immunology / Q000473:pathology; D007943:Leukemia, Hairy Cell / Q000145:classification* / Q000276:immunology / Q000473:pathology; D010641:Phenotype
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm