Ig CDR3 PCR. DNA was isolated from PBMCs, amplified following an established protocol (see “CDR3 PCR”) and run on a 12% polyacrylamide gel. Polyclonal CDR3s are indicated by the presence of DNA smears between 80 and 120 bp, the expected size range of CDR3. Monoclonal and oliglonal CDR3s are reflected by the presence of solitary, or 2 to 3 bands, respectively, in the expected size range (A). Densitometric analysis of gel bands (B). *Patients with MC.