Clonotypic PCR technique.

The CDR-III region is formed by the sequential D-J_H and V-J_H rearrangements in the pre-B cell. Both joins involve the addition of nontemplated “N” sequences and are therefore clone specific. (1) The V-D-J rearrangement is amplified by PCR using the family-specific V_HL primers. A 550-bp product represents the rearranged V_H allele. (2) The PCR product is sequenced directly, and primers are selected (3) from within the N-D-N region that are clonotypic. (4, 5) Samples are amplified in a semi-nested reaction and (6) are displayed on a high-resolution agarose gel.