How can clonality be judged using FLC assays?
Using electrophoresis methods, clonality is judged by the appearance of a narrow protein band. Using FLC assays, clonality is judged by the numerical ratio of free κ to free λ concentrations. In a similar manner, B-cell clonality in leukaemia is assessed by cellular κ/λ ratios using flow cytometry. Arguably, numerical FLC ratios are more accurate than visual assessments of stained bands on electrophoresis gels. Furthermore, in NSMM, clonality may not be apparent by any electrophoretic procedure but is usually identified by serum κ/λ ratios. In the situation of biclonal gammopathies, with increased synthesis of both free κ and λ molecules, free κ/λ ratios may be normal but the concentrations of both FLCs will be raised.
