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Analysis of the human VH gene repertoire. Differential effects of selection and somatic hypermutation on human peripheral CD5(+)/IgM+ and CD5(-)/IgM+ B cells.

ABSTRACT: To analyze the immunoglobulin repertoire of human IgM+ B cells and the CD5(+) and CD5(-) subsets, individual CD19(+)/ IgM+/CD5(+) or CD5(-) B cells were sorted and non-productive as well as productive VH gene rearrangements were amplified from genomic DNA and sequenced. In both subsets, the VH3 family was overrepresented largely as a result of preferential usage of a small number of specific individual family members. In the CD5(+) B cell subset, all other VH families were found at a frequency expected from random usage, whereas in the CD5(-) population, VH4 appeared to be overrepresented in the nonproductive repertoire, and also negatively selected since it was found significantly less often in the productive compared to the nonproductive repertoire; the VH1 family was significantly diminished in the productive rearrangements of CD5(-) B cells. 3-23/DP-47 was the most frequently used VH gene segment and was found significantly more often than expected from random usage in productive rearrangements of both CD5(+) and CD5(-) B cells. Evidence for selection based on the D segment and the JH gene usage was noted in CD5(+) B cells. No differences were found between the B cell subsets in CDR3 length, the number of N-nucleotides or evidence of exonuclease activity. Somatically hypermutated VHDJH rearrangements were significantly more frequent and extensive in CD5(-) compared to CD5(+) IgM+ B cells, indicating that IgM+ memory B cells were more frequent in the CD5(-) B cell population. Of note, the frequency of specific VH genes in the mutated population differed from that in the nonmutated population, suggesting that antigen stimulation imposed additional biases on the repertoire of IgM+ B cells. These results indicate that the expressed repertoire of IgM+ B cell subsets is shaped by recombinational bias, as well as selection before and after antigen exposure. Moreover, the influences on the repertoires of CD5(+) and CD5(-) B cells are significantly different, suggesting that human peripheral blood CD5(+) and CD5(-) B cells represent different B cell lineages, with similarities to murine B-1a and B-2 subsets, respectively.

SUBMITTER: Brezinschek HP

PROVIDER: S-EPMC508090 | biostudies-other | 1997 May

REPOSITORIES: biostudies-other

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Analysis of the human VH gene repertoire. Differential effects of selection and somatic hypermutation on human peripheral CD5(+)/IgM+ and CD5(-)/IgM+ B cells.

Brezinschek H P HP Foster S J SJ Brezinschek R I RI Dörner T T Domiati-Saad R R Lipsky P E PE

The Journal of clinical investigation 19970501 10

To analyze the immunoglobulin repertoire of human IgM+ B cells and the CD5(+) and CD5(-) subsets, individual CD19(+)/ IgM+/CD5(+) or CD5(-) B cells were sorted and non-productive as well as productive VH gene rearrangements were amplified from genomic DNA and sequenced. In both subsets, the VH3 family was overrepresented largely as a result of preferential usage of a small number of specific individual family members. In the CD5(+) B cell subset, all other VH families were found at a frequency e ...[more]

PMID: 9153293

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Project description:Adult cartilaginous fish express three immunoglobulin (Ig) isotypes, IgM, IgNAR and IgW. Newborn nurse sharks, Ginglymostoma cirratum, produce 19S (multimeric) IgM and monomeric/dimeric IgM1gj, a germline-joined, IgM-related VH, and very low amounts of 7S (monomeric) IgM and IgNAR proteins. Newborn IgNAR VH mRNAs are diverse in the complementarity-determining region 3 (CDR3) with non-templated nucleotide (N-region) addition, which suggests that, unlike in many other vertebrates, terminal deoxynucleotidyl transferase (TdT) expressed at birth is functional. IgW is present in the lungfish, a bony fish sharing a common ancestor with sharks 460 million years ago, implying that the IgW VH family is as old as the IgM VH family. This nurse shark study examined the IgM and IgW VH repertoire from birth through adult life, and analyzed the phylogenetic relationships of these gene families.IgM and IgW VH cDNA clones isolated from newborn nurse shark primary and secondary lymphoid tissues had highly diverse and unique CDR3 with N-region addition and VDJ gene rearrangement, implicating functional TdT and RAG gene activity. Despite the clear presence of N-region additions, newborn CDR3 were significantly shorter than those of adults. The IgM clones are all included in a conventional VH family that can be classified into five discrete groups, none of which is orthologous to IgM VH genes in other elasmobranchs. In addition, a novel divergent VH family was orthologous to a published monotypic VH horn shark family. IgW VH genes have diverged sufficiently to form three families. IgM and IgW VH serine codons using the potential somatic hypermutation hotspot sequence occur mainly in VH framework 1 (FR1) and CDR1. Phylogenetic analysis of cartilaginous fish and lungfish IgM and IgW demonstrated they form two major ancient gene groups; furthermore, these VH genes generally diversify (duplicate and diverge) within a species.As in ratfish, sandbar and horn sharks, most nurse shark IgM VH genes are from one family with multiple, heterogeneous loci. Their IgW VH genes have diversified, forming at least three families. The neonatal shark Ig VH CDR3 repertoire, diversified via N-region addition, is shorter than the adult VDJ junction, suggesting one means of postnatal repertoire diversification is expression of longer CDR3 junctions.

Project description:Polyreactive (natural) antibodies are primarily IgM and account for a major proportion of circulating Ig in humans. They use various V gene segments, in general, in germ line (unmutated) configuration. To analyze the VH regions of polyreactive antibodies, with particular attention at their somatically mutated status, we generated five IgG (three IgG1 and two IgG3) mAb (using B cells from a healthy subject, a patient with insulin-dependent diabetes mellitus and a patient with SLE), which bound with various efficiencies a number of different self and foreign Ag. Gene cloning experiments showed that the VH region sequences were unique to each IgG mAb. The H chain complementary determining region (CDR3) of two IgG (mAb10 and mAb426.4.2F20) displayed an identical stretch of five amino acids (RFLEW), but the other three IgG mAb CDR3 were divergent in both length and composition. The VH gene sequences of two IgG, mAb426.4.2F20 and mAb410.7.F91, were 99% identical to those of the germ line VH4.11 and VH4.21 genes, respectively. Those of the remaining three IgG mAb displayed a number of differences (93.6 to 95.9% identity) when compared with the germ line VH4.18, VH4.11, and hv1263 gene sequences. These and the VH4.21 gene have been found to encode polyreactive IgM and IgA and, in mutated configuration, monoreactive high affinity autoantibodies and antibodies induced by foreign Ag. When compared with the respective framework region, the CDR of three IgG mAb VH segment sequences displayed a significantly higher: 1) frequency of total nucleotide differences (6.1 x 10(-2) vs 4.5 x 10(-2) difference/base); 2) frequency of putative nucleotide changes yielding amino acid replacements (5.6 x 10(-2) vs 1.4 x 10(-2) replacement change/base); and 3) ratio of overall putative replacement to silent (R:S) mutations (11.0 vs 0.4). Thus, the distribution and nature of the nucleotide differences were consistent with a process of somatic mutation and Ag-dependent clonal selection. This was formally proved in IgG mAb426.12.3F1.4 and IgG mAb10 by differentially targeted polymerase chain reaction amplification and cloning and sequencing of the germ line genes that gave rise to the expressed VH segments, using DNA from polymorphonuclear cells of the same subjects whose B cells were used for the generation of these IgG mAb. Somatic mutations might have been responsible for bringing about polyreactivity in originally monoreactive antibodies or, more likely, they accumulated in originally polyreactive antibodies, which after undergoing a process of Ag selection, retained polyreactivity and may have or may have not acquired a higher affinity for the selecting Ag.

Dataset Information

Analysis of the human VH gene repertoire. Differential effects of selection and somatic hypermutation on human peripheral CD5(+)/IgM+ and CD5(-)/IgM+ B cells.

Publications

Analysis of the human VH gene repertoire. Differential effects of selection and somatic hypermutation on human peripheral CD5(+)/IgM+ and CD5(-)/IgM+ B cells.

Similar Datasets

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