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Mutations in the human lambda5/14.1 gene result in B cell deficiency and agammaglobulinemia.

Minegishi Y, Coustan-Smith E, Wang YH, Cooper MD, Campana D, Conley ME - J. Exp. Med. (1998)

Bottom Line: The three substitutions correspond to the sequence in the lambda5/14. 1 pseudogene 16.1 and result in an amino acid substitution at an invariant proline.When expressed in COS cells, the allele carrying the pseudogene sequence resulted in defective folding and secretion of mutant lambda5/14.1.These findings indicate that expression of the functional lambda5/14.1 is critical for B cell development in the human.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, St. Jude Children's Research Hospital, Memphis, Tennesse 38105, USA.

ABSTRACT
B cell precursors transiently express a pre-B cell receptor complex consisting of a rearranged mu heavy chain, a surrogate light chain composed of lambda5/14.1 and VpreB, and the immunoglobulin (Ig)-associated signal transducing chains, Igalpha and Igbeta. Mutations in the mu heavy chain are associated with a complete failure of B cell development in both humans and mice, whereas mutations in murine lambda5 result in a leaky phenotype with detectable humoral responses. In evaluating patients with agammaglobulinemia and markedly reduced numbers of B cells, we identified a boy with mutations on both alleles of the gene for lambda5/14.1. The maternal allele carried a premature stop codon in the first exon of lambda5/14.1 and the paternal allele demonstrated three basepair substitutions in a 33-basepair sequence in exon 3. The three substitutions correspond to the sequence in the lambda5/14. 1 pseudogene 16.1 and result in an amino acid substitution at an invariant proline. When expressed in COS cells, the allele carrying the pseudogene sequence resulted in defective folding and secretion of mutant lambda5/14.1. These findings indicate that expression of the functional lambda5/14.1 is critical for B cell development in the human.

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Flow cytometric analysis of bone marrow B cell precursors  from a normal age-matched control (left) and the patient with mutations  in λ5/14.1 (right). (A) Isometric contour plots of lymphoid-gated cells  stained with antibodies to CD19 and surface immunoglobulin (kappa +  lambda light chains). In the control, 46% of cells were CD19+, of which  29% were surface Ig (sIg)+. In the patient, 6% of cells were CD19+, with  only 0.7% of which were sIg+. (B) Three-color immunofluorescence was  used to stain cells for CD19, CD34, and sIg and CD19+ cells were analyzed. In the control sample, 11% of CD19+ cells were CD34+ and 60%  were CD34−, sIg−. In the patient, 87% of CD19+ cells were CD34+. (C)  Permeabilized cells were stained for TdT and surface or cytoplasmic IgM.  In the control, 5% of cells were TdT+, IgM−, 1% were TdT+, IgM+, and  40% were TdT−, IgM+. In the patient, 5% of cells were TdT+, IgM−,  0.2% were TdT+, IgM+, and 0.4% were TdT−, IgM+.
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Figure 4: Flow cytometric analysis of bone marrow B cell precursors from a normal age-matched control (left) and the patient with mutations in λ5/14.1 (right). (A) Isometric contour plots of lymphoid-gated cells stained with antibodies to CD19 and surface immunoglobulin (kappa + lambda light chains). In the control, 46% of cells were CD19+, of which 29% were surface Ig (sIg)+. In the patient, 6% of cells were CD19+, with only 0.7% of which were sIg+. (B) Three-color immunofluorescence was used to stain cells for CD19, CD34, and sIg and CD19+ cells were analyzed. In the control sample, 11% of CD19+ cells were CD34+ and 60% were CD34−, sIg−. In the patient, 87% of CD19+ cells were CD34+. (C) Permeabilized cells were stained for TdT and surface or cytoplasmic IgM. In the control, 5% of cells were TdT+, IgM−, 1% were TdT+, IgM+, and 40% were TdT−, IgM+. In the patient, 5% of cells were TdT+, IgM−, 0.2% were TdT+, IgM+, and 0.4% were TdT−, IgM+.

Mentions: Bone marrow cells from the patient and a normal age-matched control were stained in suspension with antibodies to surface immunoglobulin and CD19. Although a small number of CD19+ cells could be detected, there were almost no mature B cells as defined by coexpression of CD19 and surface immunoglobulin (Fig. 4 A). Over 85% of the CD19+ cells were positive for CD34 (Fig. 4 B), indicating a block at the transition between the pro–B cell and pre–B cell stage of differentiation. This block was also seen in permeabilized cells stained for terminal deoxynucleotidyl transferase (TdT) and surface or cytoplasmic IgM (Fig. 4 C). Although the number of TdT+ cells in the patient was comparable to the control, there were very few cells at the next stage of differentiation, cells which express cytoplasmic mu heavy chain. Bone marrow from λ5 knockout mice has markedly decreased expression of VpreB (36), suggesting that in the absence of λ5, VpreB is unstable. In bone marrow of controls, a mean of 82% of TdT+ cells was dimly positive for cytoplasmic VpreB, whereas, in the patient, 14% of the TdT+ cells were VpreB+.


Mutations in the human lambda5/14.1 gene result in B cell deficiency and agammaglobulinemia.

Minegishi Y, Coustan-Smith E, Wang YH, Cooper MD, Campana D, Conley ME - J. Exp. Med. (1998)

Flow cytometric analysis of bone marrow B cell precursors  from a normal age-matched control (left) and the patient with mutations  in λ5/14.1 (right). (A) Isometric contour plots of lymphoid-gated cells  stained with antibodies to CD19 and surface immunoglobulin (kappa +  lambda light chains). In the control, 46% of cells were CD19+, of which  29% were surface Ig (sIg)+. In the patient, 6% of cells were CD19+, with  only 0.7% of which were sIg+. (B) Three-color immunofluorescence was  used to stain cells for CD19, CD34, and sIg and CD19+ cells were analyzed. In the control sample, 11% of CD19+ cells were CD34+ and 60%  were CD34−, sIg−. In the patient, 87% of CD19+ cells were CD34+. (C)  Permeabilized cells were stained for TdT and surface or cytoplasmic IgM.  In the control, 5% of cells were TdT+, IgM−, 1% were TdT+, IgM+, and  40% were TdT−, IgM+. In the patient, 5% of cells were TdT+, IgM−,  0.2% were TdT+, IgM+, and 0.4% were TdT−, IgM+.
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Related In: Results  -  Collection

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Figure 4: Flow cytometric analysis of bone marrow B cell precursors from a normal age-matched control (left) and the patient with mutations in λ5/14.1 (right). (A) Isometric contour plots of lymphoid-gated cells stained with antibodies to CD19 and surface immunoglobulin (kappa + lambda light chains). In the control, 46% of cells were CD19+, of which 29% were surface Ig (sIg)+. In the patient, 6% of cells were CD19+, with only 0.7% of which were sIg+. (B) Three-color immunofluorescence was used to stain cells for CD19, CD34, and sIg and CD19+ cells were analyzed. In the control sample, 11% of CD19+ cells were CD34+ and 60% were CD34−, sIg−. In the patient, 87% of CD19+ cells were CD34+. (C) Permeabilized cells were stained for TdT and surface or cytoplasmic IgM. In the control, 5% of cells were TdT+, IgM−, 1% were TdT+, IgM+, and 40% were TdT−, IgM+. In the patient, 5% of cells were TdT+, IgM−, 0.2% were TdT+, IgM+, and 0.4% were TdT−, IgM+.
Mentions: Bone marrow cells from the patient and a normal age-matched control were stained in suspension with antibodies to surface immunoglobulin and CD19. Although a small number of CD19+ cells could be detected, there were almost no mature B cells as defined by coexpression of CD19 and surface immunoglobulin (Fig. 4 A). Over 85% of the CD19+ cells were positive for CD34 (Fig. 4 B), indicating a block at the transition between the pro–B cell and pre–B cell stage of differentiation. This block was also seen in permeabilized cells stained for terminal deoxynucleotidyl transferase (TdT) and surface or cytoplasmic IgM (Fig. 4 C). Although the number of TdT+ cells in the patient was comparable to the control, there were very few cells at the next stage of differentiation, cells which express cytoplasmic mu heavy chain. Bone marrow from λ5 knockout mice has markedly decreased expression of VpreB (36), suggesting that in the absence of λ5, VpreB is unstable. In bone marrow of controls, a mean of 82% of TdT+ cells was dimly positive for cytoplasmic VpreB, whereas, in the patient, 14% of the TdT+ cells were VpreB+.

Bottom Line: The three substitutions correspond to the sequence in the lambda5/14. 1 pseudogene 16.1 and result in an amino acid substitution at an invariant proline.When expressed in COS cells, the allele carrying the pseudogene sequence resulted in defective folding and secretion of mutant lambda5/14.1.These findings indicate that expression of the functional lambda5/14.1 is critical for B cell development in the human.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, St. Jude Children's Research Hospital, Memphis, Tennesse 38105, USA.

ABSTRACT
B cell precursors transiently express a pre-B cell receptor complex consisting of a rearranged mu heavy chain, a surrogate light chain composed of lambda5/14.1 and VpreB, and the immunoglobulin (Ig)-associated signal transducing chains, Igalpha and Igbeta. Mutations in the mu heavy chain are associated with a complete failure of B cell development in both humans and mice, whereas mutations in murine lambda5 result in a leaky phenotype with detectable humoral responses. In evaluating patients with agammaglobulinemia and markedly reduced numbers of B cells, we identified a boy with mutations on both alleles of the gene for lambda5/14.1. The maternal allele carried a premature stop codon in the first exon of lambda5/14.1 and the paternal allele demonstrated three basepair substitutions in a 33-basepair sequence in exon 3. The three substitutions correspond to the sequence in the lambda5/14. 1 pseudogene 16.1 and result in an amino acid substitution at an invariant proline. When expressed in COS cells, the allele carrying the pseudogene sequence resulted in defective folding and secretion of mutant lambda5/14.1. These findings indicate that expression of the functional lambda5/14.1 is critical for B cell development in the human.

Show MeSH
Related in: MedlinePlus