Clonal cell surface structures related to differentiation, activation and homing in B‐cell chronic lymphocytic leukemia and monoclonal lymphocytosis of undetermined significance

Abstract

Cell surface structures related to differntiation, activation and "homing" were identified on the leukemic cell clone in blood 64 patients with a monoclonal B-cell lymphoproliferative disorder. Patients were selected with regard to clinical signs and symptoms of the disease. 39 patients had progressive chronic lymphocytic leukemia of B-cell type (B-CLL): 16 with lymph node enlargement and 14 with progressive lymphocytosis as the most prominent symptom, respectively. 1 patient has an isolated splenomegaly and 8 had symptoms from enlarged lymph nodes, lymphocytosis and/or splenomegaly. 25 patients had an isolated monoclonal B-cell lymphocytosis in blood and bone-marrow but no other signs or symptoms of the disease. The lymphocytosis in these patients was considered to be of "undetermined significance" and the term B-cell lymphocytosis of undetermined significance (B-MLUS) was used. Patients with a prominent lymphadenopathy and/or splenomegaly had CD22+ leukemic cells while in patients with a progressive lymphocytosis the B-cell clone expressed Leu-8. Thus, CD22 might be related to the homing capacity of B lymphocyte for lymphnodes and spleen, while Leu-8 might define a circulating B-cell subset. In B-MLUS about about 50% of the monoclonal B cells co-expressed Leu 8 which is consistent with a more differentiated phenotype compared to B-CLL with progressive lymphocytosis. The CD22 expression was mostly low in B-MLUS although a few patients showed high values. The expression of receptors for growth factors (CD23, CD25, CD71) was higher in B-CLL compared to B-MLUS patients (p < 0.001), which consistent witha difference in lymphocyte activation stage and/or response to growth factors.