Abstract
Hairy cell leukemia (HCL) in the Japanese patients is not only rare but is atypical in certain clinical and hematological features. In order to investigate if Japanese HCL is atypical also in the immunophenotype, 11 patients with HCL and 11 control patients with non-Hodgkin's lymphomas were studied, utilizing their frozen mononuclear cells which had been stored for up to 5.5 years.
After thawing and trypane blue exclusion, the viable cells were partly tested for M-rosetting and mostly processed for light- and electron-microscopic examinations after fixation with PLP fixative, frozen section and immuno-staining using a panel of monoclonal antibodies.
Results indicated Japanese HCL to derive from a late stage mature B cells because most patients were phenotyped as Smlg+, HLA-DR+, B1+, B2-, FMC7+, Tac+, just as would be the case for non-Japanese patients. Remaining phenotypes, however, were J5+, Leu1+. αHC1-, αHC2- in contrast to J5-, Leu1-, αHC1+, αHC2+ known for most non-Japanese patients. We conclude Japanese HCL constitutes a special variant of HCL because it differs from the rest in clinical, hematologic, and immunologic features.
