IgM H CDR3 fingerprinting after (A) allogeneic BMT (patient no. 1), (B) autologous PBSCT (patient no. 9), and (C) CD34 selected autologous PBSCT (patient no. 11). IgM H CDR3s were amplified in PCRs using PBMC cDNA as described in Materials and Methods. The Ig H panV_H (consensus) primer, V_H3 primer, or V_H6 primer was used in combination with the Cμ primers to obtain panV_H, V_H3, or V_H6 fingerprinting profiles, respectively. PCR products were run on 5% polyacrylamide sequencing gels that result in resolution of CDR3s according to basepair size. Therefore, each band in fingerprinting corresponds to a certain CDR3 size. Molecular markers (MW) are provided of known basepair size and the corresponding number of encoded aa. Bands are separated from each other by 3 bp because of the abundance of in-frame Ig transcripts in total RNA. Nevertheless, violation of 3-bp spacing of bands can be seen occasionally. The numbers above the lanes indicate the number of weeks when the blood samples were collected posttransplant. Lanes marked NL show the H CDR3 profiles of a normal donor. The number of bands in each lane correlates directly with the repertoire diversity. The band intensity reflects the total amount of CDR3 transcripts that comprise the band. The band intensities are comparable to each other within a lane. Absolute lymphocyte counts per microliter at corresponding weeks were as follows: (A) 10 (2 weeks), 136 (3 weeks), 196 (4 weeks), 398 (5 weeks), 1,175 (7 weeks), 1,479 (10 weeks), 1,295 (12 weeks), 627 (14 weeks), 910 (24 weeks), and 1,240 (36 weeks); (B) 200 (2 weeks), 500 (4 weeks), 1,918 (6 weeks), 1,500 (19 weeks), and 1,231 (36 weeks); (C) 19 (2 weeks), 200 (3 weeks), 700 (4 weeks), 400 (6 weeks), 1,000 (7 weeks), and 1,100 (26 weeks). Shown are IgM fingerprinting profiles representative of 11 patients and normal donors of allogeneic BMT recipients.