Prognostic significance of serum immunoglobulin paraprotein in chronic lymphocytic leukemia

OBJECTIVE: To investigate the incidence of serum immunoglobulin (Ig) paraprotein in chronic lymphocytic leukemia (CLL), and to explore its clinical associated laboratory features and prognostic implication. METHODS: Serum protein electrophoresis and immunofixation electrophoresis were performed by automatic electrophoresis apparatus to identify serum Ig paraprotein. Immunonephelometry was used to measure serum Ig levels. RESULTS: Out of 101 CLL patients, serum Ig paraprotein detection was found in 20 (19.8%) cases, 13 (12.9%) patients with IgG paraprotein, 7 (6.9%) patients with IgM paraprotein and 1(1.0%) patient with IgA paraprotein. Among these 20 cases, 1 patient had both IgG and IgM paraprotein, 2 patients had both κ and λ light chains. The incidence of serum IgG paraprotein was high in the group of advanced Binet stage (P = 0.032) and high level of thymidine kinase 1 (TK1) (P = 0.013). The incidence of serum IgM paraprotein was high in the group of advanced Binet stage (P = 0.037), high level of TK1 (P = 0.017) and cytogenetic abnormalities of del(11q22.3) (P = 0.006). With a median follow-up of 30 months (range 1 - 101 months), 66 patients received therapy after initial diagnosis. Survival analysis showed that the patients with serum Ig paraprotein had significantly shorter treatment-free survival (TFS) times than the patients without serum Ig paraprotein (P = 0.024). And the patients with serum IgM paraprotein had significantly shorter treatment-free survival (TFS) times than the patients without serum Ig paraprotein (P = 0.013). However, serum Ig paraprotein or IgM paraprotein was not independent prognostic factor. CONCLUSION: Serum Ig paraprotein can be detected in a subset of patients with CLL, which could be of value as a prognostic factor in CLL.