The C104R mutant impairs the function of transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) through haploinsufficiency - PubMed (original) (raw)

The C104R mutant impairs the function of transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) through haploinsufficiency

John J Lee et al. J Allergy Clin Immunol. 2010 Dec.

Abstract

Background: TNFRSF13B, which encodes transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), is mutated in 10% of patients with common variable immunodeficiency. One of the 2 most common TACI mutations in common variable immunodeficiency, C104R, abolishes ligand binding and is found predominantly in the heterozygous state. The murine TACI mutant C76R is the equivalent of the human TACI mutant C104R.

Objective: We sought to define the consequence of the C76R mutation on TACI function in mice that express both wild-type TACI and the murine C76R mutant.

Methods: Transgenic mice that express murine TACI C76R, the counterpart of human TACI C104R, on the TACI(+/-) B6/129 background (C76R/TACI(+/-) mice) were constructed. Serum immunoglobulins and antibody responses to the type II T-independent antigen trinitrophenylated (TNP)-Ficoll were determined by means of ELISA. B-cell proliferation in response to a proliferation-inducing ligand was determined based on tritiated thymidine incorporation into DNA. IgG1 secretion by B cells in response to a proliferation-inducing ligand plus IL-4 was determined by means of ELISA.

Results: C76R/TACI(+/-) mice had significantly impaired antibody responses to the type II T-independent antigen TNP-Ficoll compared with TACI(+/+) B6/129 control animals, and their B cells were impaired in their capacity to proliferate and secrete IgG1 in response to TACI ligation. Unexpectedly, TACI(+/-) mice had similarly impaired B-cell function as C76R/TACI(+/-) littermates. Impaired TACI function caused by haploinsufficiency was confirmed in TACI(+/-) mice on the C57BL/6 background.

Conclusion: These results suggest that the human TACI mutant C104R might impair TACI function in heterozygotes through haploinsufficiency.

Copyright © 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

PubMed Disclaimer

Figures

FIG 1

FIG 1

Characterization of C76R/TACI+/− transgenic mice. A, Schematic representation of the murine C76R TACI (mTACI) transgene. EC, extracellular; IC, intracellular; TM, transmembrane. B and C, Representative FACS analysis of splenocytes from TACI+/+, TACI−/−, C76R/TACI+/−, and TACI+/− mice for B220 and TACI surface expression. Relevant quadrant percentages and MFIs are provided. TACI expression on B220+ B cells (Fig 1, B) and CD4 and B220 expression (Fig 1, C) are shown. Fig 1, B, also shows TACI surface expression on WT Tg/TACI+/− mice, which were not further studied because the percentage of their B cells that expressed TACI and the intensity of TACI expression on these B cells were significantly higher than in TACI+/+ mice and C76R/TACI+/− mice.

FIG 2

FIG 2

Serum immunoglobulins and antibody responses to TNP-Ficoll in C76R/TACI+/− transgenic mice. A, Serum IgM, IgG, and IgA levels from nonimmunized 8- to 12-week-old TACI+/+, TACI−/−, TACI+/−, and C76R/TACI+/− mice. The median (center line), 25th to 75th percentiles (box), and lowest and highest values (bars) are shown for each group. B, IgM and IgG anti-TNP antibody responses to TNP-Ficoll. Bars represent SEMs. The Mann-Whitney test was used in Fig 2, A, and 2-way ANOVA was used in Fig 2, B, to calculate significance (n = 10-12 mice per group). *P < .05, **P < .01, and ***P < .001.

FIG 3

FIG 3

Proliferation and immunoglobulin synthesis in vitro by naive B cells from C76R/TACI+/− transgenic mice. Proliferation (A) and IgG1 synthesis (B) in response to APRIL are shown. B cells were stimulated with anti-CD40 plus IL-4 as a control for proliferation and IgG1 production (n = 5-9 mice per group). The Mann-Whitney test was used to calculate significance. MED, Medium alone. *P < .05, **P < .01, and ***P < .001.

FIG 4

FIG 4

Decreased serum IgA levels and impaired antibody responses to TNP-Ficoll in TACI+/− mice on the C57BL/6 background. A, TACI and B220 expression on splenocytes from TACI+/+, TACI+/−, and TACI−/− mice on the C57BL/6 background. B, Serum IgM, IgG, and IgA levels from nonimmunized 8- to 12-week-old mice. C, IgM and IgG anti-TNP antibody responses to TNP-Ficoll. The results in Fig 4, B and C, are presented and analyzed as in Fig 2 (n = 10-12 mice per group).

FIG 5

FIG 5

Proliferation and immunoglobulin synthesis in vitro by purified B cells from TACI+/− mice on the C57BL/6 background. Proliferation (A) and IgG1 synthesis (B) in response to APRIL are shown (n = 5-9 mice per group). Results were analyzed as in Fig 3. MED, medium alone. *P < .05, **P < .01, and ***P < .001.

FIG E1

FIG E1

TACI surface expression of C76R transgenic mice. A representative biexponential FACS plot of TACI expression on C76R/TACI−/− mice is shown. Single-cell suspensions were stained with fluorochromeconjugated antibodies in PBS containing 1% BSA and Fc-block (BD PharMingen), washed, and analyzed on a FACSCanto cytometer (Becton Dickinson). Conjugated anti-mouse mAbs used were fluorescein isothiocyanate–labeled anti-B220 (RA3-6B2, BD PharMingen) and phycoerythrin-labeled anti-mouse TACI (R&D Systems).

FIG E2

FIG E2

Antibody responses to KLH in C76R/TACI+/− transgenic mice. Mice (n = 4 per group) were immunized on day 0 with 200 μg of KLH administered intraperitoneally and 200 μg of KLH administered subcutaneously, boosted on day 14 with 25 μg of KLH, and bled on day 21. Plates were coated with KLH (10 μg/mL) in sodium carbonate buffer (pH 9.0) to measure anti-KLH–specific antibody. The wells were blocked with 2% BSA for 2 hours and incubated with diluted sera overnight at 4°C. Alkaline phosphatase–conjugated isotype-specific antibodies (BD PharMingen) were used as revealing antibodies. None of the differences between groups were significant, as analyzed with the Mann-Whitney test.

Similar articles

Cited by

References

    1. International Union of Immunological Societies Primary immunodeficiency diseases. Report of an IUIS Scientific Committee. Clin Exp Immunol. 1999;118(suppl 1):1–28. - PMC - PubMed
    1. Cunningham-Rundles C, Bodian C. Common variable immunodeficiency: clinical and immunological features of 248 patients. Clin Immunol. 1999;92:34–48. - PubMed
    1. Di Renzo M, Pasqui AL, Auteri A. Common variable immunodeficiency: a review. Clin Exp Med. 2004;3:211–7. - PubMed
    1. Castigli E, Wilson SA, Garibyan L, Rachid R, Bonilla F, Schneider L, et al. TACI is mutant in common variable immunodeficiency and IgA deficiency. Nat Genet. 2005;37:829–34. - PubMed
    1. Salzer U, Chapel HM, Webster AD, Pan-Hammarstrom Q, Schmitt-Graeff A, Schlesier M, et al. Mutations in TNFRSF13B encoding TACI are associated with common variable immunodeficiency in humans. Nat Genet. 2005;37:820–8. - PubMed

Publication types

MeSH terms

Substances

Grants and funding

LinkOut - more resources