The human immunoglobulin x locus. Characterization of the duplicated A regions

The antibody response to H. influenzae type b (Hib) is pauciclonal, and is dominated by antibodies using the V A2 gene. Navajos have a 5-10-fold increased incidence of Hib disease compared with control populations. We hypothesized that a polymorphism in one of the genes in this oligoclonal response may lead to increased disease susceptibility. Since the predominant A2 + anti-Hib antibodies have high avidity for Hib and can be unmutated, the A2 V gene was analyzed. Over half of the Navajos studied, but only one control individual, had a new allele of A2, termed A2b, with three changes from the published A2 germline sequence. One of the changes was in the recombination signal sequence, suggesting that the A2b allele might not undergo V-J rearrangement very frequently. This possibility was confirmed by analyzing the relative frequency of non-productive A2 rearrangements in A2a/b heterozygous Navajos. Many fewer A2b rearrangements were observed, showing that the A2b allele is defective in its ability to undergo rearrangement. The prevalence of this allele in Navajos may play a role in their increased susceptibility to invasive Hib disease. If so, it would underscore the importance of the germline Ig repertoire for protective antibody responses to pathogenic bacteria in unimmunized children. ( J. Clin. Invest . 1996. 97: 2277-2282.)

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A defective Vkappa A2 allele in Navajos which may play a role in increased susceptibility to haemophilus influenzae type b disease.

Feeney¹,

Atkinson²,

Cowan³

et al. 1996

“…Although these defects may explain underutilization of these V genes, not all putatively defective genes, including A20, are rearranged infrequently. For example, A20, has a defective recombination signal sequence as a result of a single base pair substitution at the fourth position of the heptamer (19). Although this defect would be predicted to reduce efficiency of recombination (20), A20 was found at the expected frequency in VJ rearrangements.…”

Section: Discussionmentioning

confidence: 99%

Molecular mechanisms and selective influences that shape the kappa gene repertoire of IgM+ B cells.

Foster

Brezinschek²,

Brezinschek³

et al. 1997

135

175

To analyze the human kappa chain repertoire and the influences that shape it, a single cell PCR technique was used that amplified V J rearrangements from genomic DNA of individual human B cells. More than 350 productive and 250 nonproductive V J rearrangements were sequenced. Nearly every functional V gene segment was used in rearrangements, although six V gene segments, A27, L2, L6, L12a, A17, and O12/O2 were used preferentially. Of these, A27, L2, L6, and L12a showed evidence of positive selection based on the variable region and not CDR3, whereas A17 was overrepresented because of a rearrangement bias based on molecular mechanisms. Utilization of J segments was also nonrandom, with J 1 and J 2 being overrepresented and J 3 and J 5 underrepresented in the nonproductive repertoire, implying a molecular basis for the bias. In B cells with two V J rearrangements, marked differences were noted in the V segments used for the initial and subsequent rearrangements, whereas J segments were used comparably. Junctional diversity was generated by n-nucleotide addition in 60% and by exonuclease trimming in 75% of the V J rearrangements analyzed. Despite this large degree of diversity, a strict CDR3 length was maintained in both productive and nonproductive rearrangements. More than 23% of the productive rearrangements, but only 7% of the nonproductive rearrangements contained somatic hypermutations. Mutations were significantly more frequent in V sequences derived from CD5Ϫ as compared with CD5

“…m659-2, which was isolated from the downstream region of A29 germline gene, was kindly provided by Prof. H.G. Zachau (University of Munich, Munich, Germany) (23). m659-2 is one of the duplication differentiating polymorphism, DDP, probe of the proximal A region of human Ig Vk locus (10).…”

Section: Introductionmentioning

confidence: 99%

“…1 and Table I. The A29 primer was designed to distinguish A29 Vk gene (23) from A13 Vk gene (23), which is reported to be a duplicated copy of the A29 gene. 100 ng of genomic DNA of the neutrophils or purified B cells was added to 50 l reaction mixture of the kit and amplified as follows: 35 cycles at 98 Њ C for 20 s, 68 Њ C for 15 min, after 2 min at 94 Њ C, and then a final 10 min at 72 Њ C. The PCR products were hybridized to the probes mentioned in Fig.…”

Section: Introductionmentioning

confidence: 99%

Characterization of a germline Vk gene encoding cationic anti-DNA antibody and role of receptor editing for development of the autoantibody in patients with systemic lupus erythematosus.

Suzuki¹,

Harada²,

Mihara³

et al. 1996

We found previously that cationic anti-DNA autoantibodies (autoAbs) have nephritogenic potential and usage of a specific germline Vk gene, A30, has major influences on cationic charge of the autoAb in human lupus nephritis. In the present study, we have characterized A30 germline Vk gene using cosmid cloning technique in patients with SLE. A30 gene locus locates in less than 250 kb from the Ck region, and the cationic anti-DNA mRNA used the upstream Jk2 gene, indicating that cationic anti-DNA mRNA is a product of primary gene rearrangement. By using PCR technique, we found that A30 gene locus in the genome was defective in eight out of nine SLE patients without nephritis.