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Developmental Immunology
Volume 4 (1994), Issue 1, Pages 13-26

Expression of λ and K Genes Can Occur in all B Cells and is Initiated Around the Same Pre-B-Cell Developmental Stage

1Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA
2Department of Biochemistry, Northwestern University, Evanston, Illinois, USA

Received 8 February 1994; Accepted 23 March 1994

Copyright © 1994 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Transgenic mice that carry a λ2 transgene under the control of the Vλ2 promoter and the Eλ2-4 enhancer (λ2Eλ mice) are described. A high proportion of B cells in the spleen and the bone marrow express the λ transgene on the cell membrane. λ2 protein is synthesized by all λ2Eλ-derived spleen B-cell hybridomas that have retained the transgene, suggesting that all B cells have the ability to express λ genes. Feedback inhibition of endogenous K-gene rearrangement is significant, but not complete. The results are similar to those with transgenic mice expressing the same λ2 transgene under the control of the heavy-chain enhancer (λ2EH mice). Although the λ2EH transgene is expressed before the λ2Eλ transgene, feedback inhibition seems to occur at about the same stage of B-cell development, regardless of the timing of expression of the λ transgenes. Apparently, feedback is not necessarily coincident with the assembly of a heavy-chain/light-chain complex in pre-B cells. Expression of λ in the normal fetal liver coincides with the expression of K; thus, it appears that λ-gene transcription is not delayed. The differential rearrangement of K and λ genes is discussed in the light of these findings.