OBJECTIVETo evaluate the specificity and sensitivity of immunoglobulin heavy/light chain (HLC) and serum free light chain (FLC) level in minimal residual disease monitoring of IgG type multiple myeloma (MM) patients during complete remission (CR).

METHODSImmunoglobulin HLC was assessed in 20 IgG myeloma patients by immune turbidimetry using SPAplus Analyzer. The serum level of HLC and FLC was detected at same time. Combine with those obtained by serum protein electrophoresis (SPE) and immune fixation electrophoresis (IFE), the specificity and sensitivity of HLC in detection of serum immunoglobulin were analyzed. Combined with the clinical efficacy, kappa/lambda ratios of HLC (rHLC) and FLC (rFLC) were compared between the patients and normal controls.

RESULTSAmong 20 patients, there were 10 male and 10 female, the median age was 56 years (35-70). There were 6 patients with abnormal rHLC but normal rFLC; 3 patients with abnormal rFLC but normal HLC; and 11 patients with both normal rHLC and rFLC. During the mean follow-up time of 18 months, 4 of the6 patients with abnormal rHLC accepted intervention therapies, 1 case relapsed in 9 months,the other 2 untreated patients relapsed in 3 months. Among the 3 cases with abnormal rFLC, 2 patients are still in remission after intervention therapies,the other untreated patient relapsed in 1.5 months. Among the 11 untreated patients with both normal rHLC and rFLC, 3 relapsed with the disease free survival time of 3.5 months, 5.0 months and 5.5 months respectively.

CONCLUSIONThe combined detection of HLC and FLC is helpful to assess the curative efficacy and the accuracy of minimal residual disease monitoring, and more effectively evaluate the prognosis of MM patients. Abnormal rHLC and rFLC are correlated with poor prognosis, while early intervention therapies can help to improve disease free survival.