Free light chains of immunoglobulin as a prognostic factor for some plasmaproliferative diseases

Abstract

Quantitation of monoclonal immunoglobulins and their fragments is used for monitoring the plasmaproliferative disease course and the effect of therapy. The aim of free light chains examination was to evaluate the significance of the FLC ratio as a prognostic factor for remission, progression and survival in different disease groups. The concentrations of immunoglobulins and free light chains were measured by an immunonephelometric method on a SIEMENS DADE BN II analyser with reagents (Freelite, The Binding Site, UK). In this examination 151 patients from 3 different disease groups: 1. Light chain disease or Bence Jones myeloma (37), 2. Biclonal gammopathy with FLC (23) and 3. Monoclonal gammopathy of undetermined significance (91), were investigated during a period of 7 years. The reference interval for FLC ratio is 0.26-1.65. According to the International Staging System for multiple myeloma, a serum FLC ratio of <0.03 or >32 was taken as abnormal. The patients with light chain disease and biclonal gammopathy with FLC with an abnormal FLC ratio and a combination of adverse risk factors (76.7%) had median survival times of 22-30 months, versus patients with a normal or slightly varied FLC ratio without adverse risk factors (23.3%) with median survival times of 39-51 months. About 38% of patients who had shown lowered free light chains values by more than 50% under therapy, achieved disease remission in the light chain disease and biclonal gammopathy with FLC groups. In the group of patients with monoclonal gammopathy of undetermined significance, 66.0% had a normal or slightly modified FLC ratio which corresponds to low and low-intermediate risk of disease progression, as opposed to 34.0% with an abnormal FLC ratio (<0.25 or >4) which corresponds to high and high-intermediate risk. An abnormal FLC ratio in the examined groups could be an independent risk factor for progression and poorer disease prognosis.