SOLUBLE CD23 RELIABLY REFLECTS DISEASE-ACTIVITY IN B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA

Purpose: This study was initiated to evaluate whether soluble Cd23 (sC D23) reflects disease activity and tumor load in B-cell chronic lympho cytic leukemia (B-CLL) and to determine its prognostic potential for t his disease. Patients and Methods: The concentration of sCD23 was meas ured in the serum of 45 B-CLL patients, 50 patients with other lymphop roliferative disorders, and 41 healthy donors (HD). sCD23 serum levels from B-CLL patients were correlated with parameters of disease activi ty and total tumor mass (TTM) score. In selected cases, sCD23 was meas ured repeatedly over a 24-month period. Expression, density, and calcu lated total amount of membrane CD23 on peripheral-blood B-CLL cells, a s well as its correlation to sCD23 levels in serum and supernatants, w ere determined. Results: sCD23 in B-CLL patients serum was highly elev ated compared with other lymphoproliferative disorders, with the excep tion of immunocytoma (IC). Both advanced pal stages and active forms o f B-CLL were associated with higher levels of sCD23, There was a highl y significant reciprocal relationship between sCD23 and lymphocyte cou nt doubling time (LCDT). Serum sCD23 correlated positively with serum deoxythymidine kinase activity and TIM scare, but not with absolute ly mphocyte counts, The repetitive measurement of serum sCD23 showed the usefulness of this marker in monitoring disease progression in B-CLL. The total amount of membrane CD23 on in vitro-cultured B-CLL cells cor related significantly with sCD23 levels in the supernatant, whereas co rrelation between serum sCD23 and membrane CD23 on freshly isolated B- CLL cells was absent. Conclusion: Our results indicate that sCD23 is a highly sensitive and specific parameter with prognostic potential for B-CLL, which may be used as a tumor marker and may help to assess dis ease activity. (C) 1994 by American Society of Clinical Oncology.