Analysis of Somatic Hypermutation in Mouse Peyer's Patches Using Immunoglobulin κ Light-Chain Transgenes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 90; no. 21; pp. 9862 - 9866
• Main Authors: Gonzalez-Fernandez, Africa, Milstein, Cesar
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.11.1993; National Acad Sciences
• Subjects: Amino Acid Sequence; Animals; Antigens; B lymphocytes; B-Lymphocytes - immunology; Base Sequence; Biological and medical sciences; DNA - chemistry; DNA - isolation & purification; Flow Cytometry; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Genes, Immunoglobulin; Genetic mutation; Immunobiology; Immunoglobulin kappa-Chains - genetics; Immunoglobulin Light Chains - genetics; Immunoglobulin Variable Region - genetics; Lymphoid cells: ontogeny, maturation, markers, receptors, circulation and recirculation; Lymphoid tissue; Mice; Mice, Transgenic; Molecular Sequence Data; Oligonucleotide Probes; Peyer's Patches - immunology; Peyers patches; Point Mutation; Polymerase Chain Reaction; Somatic mutation; Spleen; Transgenes; Transgenic animals; Spleen; Kappa light peptide chain; Immunoglobulins; Peyer patch; Germinative center; Hot spot; Rodentia; Transgenic animal; B-Lymphocyte; Method; Somatic mutation; Vertebrata; Mammalia; Lymphoid organ; Gene; Mouse; Immunologic repertoire; Comparative study
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.21.9862

We have exploited mice transgenic for an immunoglobulin κ light chain in order to show that immunoglobulin genes in the B cells of Peyer's patches in unimmunized mice carry a high level of somatic mutations. Most of the mutations are found in the subpopulation of B cells which, based on peanut agglutinin binding, derive from the germinal centers. The number of mutations per clone and their distribution along the variable gene segment (indicative of untemplated point mutations) are very similar to those found in antigen-specific splenic B cells of normal mice after secondary immunization. The mutations accumulate mainly in complementarity-determining region 1, in particular in some specific codons (Ser-26, Ser-31, and Ser-77) which have been previously recognized as intrinsic hypermutational hotspots. These results suggest that, as in the spleen, somatic mutation occurs in B cells which have migrated to the germinal centers, probably as a consequence of stimulation by antigens present in the gut environment. Transgenic animals are increasingly being used to define the signals involved in hypermutation. However, their subsequent study is very time-consuming because it is based on immunization and analysis of hybridomas or antigen-selected cells. We propose that the use of Peyer's patches of unimmunized adult mice offers a reliable and simple approach to analyze hypermutation of transgenes.