Southern blot analysis of switch μ/δ regions in MALT lymphoma cases No. 2 and No. 1.

Genomic DNA was digested with the indicated restriction enzymes, electrophoresed, blotted, and probed sequentially with various switch probes shown above each lane. Illegitimate switch recombination fragments are indicated by the molecular weight and germline fragments by a “g.” Seizes of the expected germline bands are reported in Figure 1. (A) Case No. 2 shows 2 illegitimate switch fragments identified by the 5′Sμ probe on a HindIII and SphI digest and 2 fragments identified by the 5′ςμ probe on a BglII digest. (B) Case No. 1 shows 1 illegitimate switch fragment identified by the 5′Sμ probe on a HindIII digest and 1 illegitimate fragment on an SphI digest, which is identified also by the 3′Sμ probe. This case shows other 2 illegitimate switch fragments with a 5′ςμ probe on a BglI digest.