Restricted kappa/lambda light chain ratio by flow cytometry in germinal center B cells in Hashimoto thyroiditis.

To determine the diagnostic significance of the kappa/lambda ratio in germinal center (GC) B cells in Hashimoto thyroiditis (HT), we used 4-color flow cytometry to immunophenotype 27 samples (21 patients) of well-characterized HT B-cell clonality was analyzed further by polymerase chain reaction (PCR) of the immunoglobulin heavy chain (IgH) and bcl-2/IgH fusion genes using DNA extracted from aspirate smears and/or paraffin-embedded tissues. By flow cytometric analysis, the CD10+ GC B cells had a higher mean +/- SD kappa/lambda ratio than the CD10- B cells (5.1 +/- 3.