CIRCULATING LEVELS OF SOLUBLE CD23 REFLECT CLINICAL AND BIOLOGICAL FEATURES OF LEUKEMIC B-CELL CHRONIC LYMPHOPROLIFERATIVE DISORDERS

One hundred and twenty-four sera from patients with various leukemic B -cell chronic lymphoproliferative diseases were investigated at diagno sis by ELISA for their soluble CD23 content. Immunophenotyping was. ca rried out in all patients, and in a selected subset the mean number of membrane-bound CD23 molecules per cell was also investigated. Seventy -three patients had typical B chronic lymphocytic leukemia, 41 leukemi c B-cell disorders with atypical morphological and/or immunophenotypic features, 5 had low-grade follicular cell lymphoma in the leukemic ph ase, and 5 had splenic lymphoma with villous lymphocytes. Soluble CD23 levels were significantly higher than in normal sera (mean+/-SD: typi cal B chronic lymphocytic leukemia 3,650+/-4,654 U/ml, atypical B chro nic lymphocytic leukemia 3,440+/-4,671 U/ml, follicular cell lymphoma 3,200+/-1,511 U/ml, splenic lymphoma with villous lymphocytes 8,236+/- 7,294 U/ml, controls 137+/-128 U/ml; P<0.001). More advanced Rai's sta ges were related to higher soluble CD23 levels (P<0.01), both in typic al and atypical B chronic lymphocytic leukemias, the highest levels an d the best correlation with the absolute number of circulating CD19(+) cells (r=0.50) being observed in the typical form. The number of memb rane-bound CD23 molecules per cell was significantly higher in typical than in atypical B chronic lymphocytic leukemias (mean number 156,727 +/-94,668 vs. 12,010+/-10,643, P<0.001). Our data suggest that soluble CD23 levels correlate with the clinical and biological features of le ukemic B-cell lymphoproliferative disorders.