A new variable region in mouse immunoglobulin lambda light chains.

A series of lambda+ murine hybridomas were derived from a BALB/c mouse after a single injection of anti-lambda 2 antibodies coupled to LPS. Nine lambda B cell clones (five lambda 2 and four lambda 3) were expected and seven reacted with antibodies specific for the C lambda 2 constant region but showed a particular isoelectric spectrum. Their RNA products did not hybridize with the V lambda probe. The partial DNA sequence of gene segments coding the unexpected light chain of one hybridoma shows that the V gene segment has only 55% homology with the V lambda 2 gene segment sequence and that J lambda 2 and probably C lambda 2 gene segments are used. Taken together, these results demonstrate the existence of a new lambda light chain.