Mouse myeloma proteins with lambda 2 and lambda 3 light chains.

Serum and ascites fluid from mice bearing 260 different myeloma tumors were screened serologically for myeloma proteins having light chains like that of L315, the lambda 2 chain produced by myeloma MOPC-315. Four proteins, made by myelomas TEPC-952, CBPC-49, ABPC-72, and SAPC-15, were identified. Their light chains were essentially indistinguishable serologically from L315, and each of them also yielded the characteristic C-terminal amino acid (leucine) and C-terminal tryptic peptide of L315. However, amino acid sequences and other findings reported elsewhere have revealed that although the light chain of TEPC-952 is indeed a lambda 2 chain, the light chains of the others (CBPC-49, ABPC-72, and SAPC-15) represent another, slightly different type of light chain, which has been designated lambda 3.