Analysis of IgM H CDR3s posttransplant by SSCP. IgM panV_H, V_H3, and V_H6 H CDR3s were amplified in nested PCRs as described in Materials and Methods. Two times the amount of PCR product used in fingerprinting experiments was loaded on to 5% polyacrylamide gels containing 5% glycerol. Gels were run at room temperature for 7 hours while being cooled by an electrical fan. Images were obtained by silver staining. In SSCP, CDR3s of the same basepair size can be separated due to differences in their mobility based on their tertiary structures. NL, normal donor. Pt, patient. Patient numbers are according to Table 1. Patient no. 12, who died of refractory NHL 2 months after an autologous PBSCT, was not included in other analyses. Bands indicated by the arrows represent renatured DNA determined by the simultaneously run control samples that were not denatured before loading (data not shown).