Heavy and light chains all at once: A new immunofluorescence technique to evaluate monoclonal immunoglobulin deposits.

Tools to identify monoclonal Ig deposits within tissue specimens include immunofluorescence (IF) staining on frozen tissue for Ig heavy chains and light chains, pronase IF to unmask monoclonal Ig deposits not seen by IF staining on frozen tissue, and IF staining for IgG subclasses (IgG1-IgG4). In this issue of Kidney International, a novel diagnostic tool is introduced: IF staining for conformational epitopes at the junction of the Ig heavy chains and light chains. This technique has the potential to significantly enhance our ability to evaluate apparent monoclonal forms of renal disease.