Human immunoglobulin kappa light-chain genes are deleted or rearranged in lambda-producing B cells

We have examined 10 human lambda light-chain-producing B lymphocytes and found that genes for the kappa constant region have been deleted in each. Only one of the 20 possible kappa alleles in these cells has been retained and even this exception is rearranged. In contrast, lambda constant region genes remain in the germ-line configuration in each of the eight kappa light-chain-producing human B lymphocytes examined. Such observations suggest a hierarchy of light-chain-gene rearrangement beginning with kappa and proceeding to lambda.