Selective cloning of B cell hybridoma-specific rearranged immunoglobulin gene loci using the polymerase chain reaction.

The use of conventional DNA cloning procedures to obtain productively rearranged Ig genes from B cell hybridomas for structure/function analysis of immunoglobulins is tedious and time-consuming. Here we describe a procedure based on PCR which permits rapid, selective isolation of DNA segments containing individual hybridoma-specific Ig gene rearrangements. The method, an adaptation of the so-called 'inverted PCR' technique (IPCR), can be applied most efficiently to specific genes where a preliminary restriction map is available from Southern blot analysis of the hybridoma genomic DNA. To achieve amplification of a given rearranged Ig locus, small amounts of total hybridoma DNA are digested to completion with a chosen restriction endonuclease and the fragments circularised by DNA ligase. Cleavage of the DNA circles using a second restriction enzyme, chosen specifically to cut 3' to a rearranged V-(D)-J exon, leads to linear DNA segments where the rearranged gene is now flanked by segments of known nucleotide sequence derived originally from the 3' region of the Ig H or L chain gene locus. This permits the selection of oligonucleotides that provide convergent primers for specific amplification of DNA segments containing the required gene rearrangement. Amplified DNA fragments can be cloned and rapidly characterised by sequence analysis.