The role of interleukin-6 in a patient with polyclonal hairy B-cell lymphoproliferative disorder: a case report.

An 80-year-old female patient showed persistent lymphocytosis morphologically resembling the Japanese variant of hairy cell leukemia (HCL). However, flow cytometric analysis determined that these lymphocytes were of polyclonal B-cell origin, showing CD5-, CD10(-), CD11c(+), CD19(+), CD20(+), CD23(-), CD103(-), FMC7(-), HLA-DR(+) and surface membrane immunoglobulin (smIg) G(+) phenotype. The female patient also showed polyclonal hypergammaglobulinemia with bone marrow plasmacytosis. The patient was diagnosed as having hairy B-cell lymphoproliferative disorder (HBLD). Serum interleukin-6 (IL-6) level was elevated at the time of diagnosis in this patient, but IL-6 receptor (CD126) was not expressed on the hairy B-cells. Intracellular IL-6 was not detected in these cells either, suggesting that IL-6 did not play an important role in the B-lymphocytosis present in our patient with HBLD.