Genetic analyses on flow-sorted PCs. (A) CD45 versus CD38 flow dot plot of BMMNCs and lymph nodes (LNs) from a patient with extramedullary myeloma (ExMM-8; Table 3). The PCs from both locations expressed high levels of CD56 and were CD19^- (data not shown). The sort gate used for generating pure CD38⁺⁺/CD45^-/CD56⁺⁺/CD19^- PCs to RAS mutational analysis is shown. (B) The V_HDJ_H gene rearrangements representing the MM clone were identified by RT-PCR using consensus V_H and J_H primers. Among BMMNCs a polyclonal V_H3 (originating from normal B cells) and a clonal V_H2 band was identified. The LN population consisted of a V_H2 clone. To verify clonal identity the V_HDJ_H gene was sequenced, showing identical complementarity-determining region (CDR) I, II, and III sequences. The CDRIII sequence is shown in panel B. (C) Direct sequencing of RAS RT-PCR products generated from BM- and LN-localized CD38⁺⁺/CD45^-/CD56⁺⁺/CD19^- PCs purified by flow sorting. The reverse sequence is shown including codon K-RAS61, with a single K-RAS61 mutation CAA to CGA in the LN. Arrows show places of mutations.