Corrigendum: Natural Killer Cells from Patients with Recombinase-Activating Gene and Non-Homologous End Joining Gene Defects Comprise a Higher Frequency of CD56bright NKG2A+++ Cells, and Yet Display Increased Degranulation and Higher Perforin Content

[This corrects the article on p. 798 in vol. 8, PMID: 28769923.].

Natural Killer Cells from Patients with Recombinase-Activating Gene and Non-Homologous End Joining Gene Defects Comprise a Higher Frequency of CD56bright NKG2A+++ Cells, and Yet Display Increased Degranulation and Higher Perforin Content

Mutations of the recombinase-activating genes 1 and 2 (RAG1 and RAG2) in humans are associated with a broad range of phenotypes. For patients with severe clinical presentation, hematopoietic stem cell transplantation (HSCT) represents the only curative treatment; however, high rates of graft failure and incomplete immune reconstitution have been observed, especially after unconditioned haploidentical transplantation. Studies in mice have shown that Rag^−/− natural killer (NK) cells have a mature phenotype, reduced fitness, and increased cytotoxicity. We aimed to analyze NK cell phenotype and function in patients with mutations in RAG and in non-homologous end joining (NHEJ) genes. Here, we provide evidence that NK cells from these patients have an immature phenotype, with significant expansion of CD56^bright CD16^−/int CD57⁻ cells, yet increased degranulation and high perforin content. Correlation was observed between in vitro recombinase activity of the mutant proteins, NK cell abnormalities, and in vivo clinical phenotype. Addition of serotherapy in the conditioning regimen, with the aim of depleting the autologous NK cell compartment, may be important to facilitate engraftment and immune reconstitution in patients with RAG and NHEJ defects treated by HSCT.

Successful interferon-alpha 2b therapy for unremitting warts in a patient with DOCK8 deficiency

The autosomal recessive form of the Hyper IgE syndrome (AR-HIES) with dedicator of cytokinesis 8 (DOCK8) deficiency is associated with difficult to treat persistent viral skin infections, including papilloma virus infection. Type I interferons play an important role in the defense against viruses. We examined the effect of therapy with IFN-α 2b in an 11-year old boy with DOCK8 deficiency due to a homozygous splice donor site mutation in DOCK8 intron 40. His unremitting warts showed dramatic response to IFN-α 2b therapy. Immunological studies revealed decreased circulating plasmacytoid dendritic cells (pDCs) and profound deficiency of IFN-α production by his peripheral blood mononuclear cells in response to treatment with CpG oligonucleotides. These findings indicate that underlying pDC deficiency and impaired IFN-α production may predispose to chronic viral infections in DOCK8 deficiency. IFN-α 2b therapy maybe useful in controlling recalcitrant viral infections in these patients.

Impaired T cell homing and transendothelial migration in CIP4 null mice caused by defective integrin-mediated adhesion (44.1)

The F-BAR domain-containing protein CIP4 interacts with Cdc42 and WASP/N-WASP and is thought to participate in the assembly of filamentous actin. CIP4-/- mice had normal T and B lymphocyte development but impaired T cell-dependent antibody production, IgG antibody affinity maturation, and germinal center formation, despite intact CD40L-CD40 axis. CIP4-/- T cells, but not B cells, homed poorly to lymphoid organs. CIP4-/- mice had impaired contact hypersensitivity (CHS) and their T cells failed to adoptively transfer CHS. CD4+ effector T cells from CIP4-/-/OT-II mice migrated poorly to antigen challenged skin. CIP4-/- T cells exhibited normal rolling on endothelial selectins and chemotaxis to SDF-1α, but impaired adhesion and polarization on immobilized VCAM-1 and ICAM-1, and defective arrest and transmigration across murine endothelial cells under shear flow conditions. These results demonstrate an important role for CIP4 in integrin-mediated T cell adhesive events that are essential for normal recruitment to lymphoid organs and sites of antigen driven immune reactions.

WIP peptide stabilizes WASP in cells from Wiskott-Aldrich syndrome (WAS) patients with mutations in the WIP-binding domain (33.16)

WAS is an X-linked immunodeficiency characterized by eczema, thrombocytopenia and recurrent infections. WAS-protein (WASP) links cell surface signals to the actin cytoskeleton. WASP is important in T cells for IL-2 production, proliferation, and migration. The WAS-interacting protein (WIP) stabilizes WASP. WASP level is severely reduced in T cells of WIP KO mice. The majority of missense mutations in WAS patients are in the WIP binding domain (WBD) of WASP and interfere with WIP binding, resulting in low WASP levels.

We identified a 35 a.a. fragment of WIP (termed nWIP), which when fused to the C-terminal of EGFP (EGFP-nWIP), interacts with WASP in Jurkat cells. When introduced into WIP KO T cells, EGFP-nWIP increased the level of WASP to normal, as determined by FACS analysis. EBV-transformed B cell lines from WAS patients with mutations in the WBD of WASP expressed low levels of WASP, but had normal mRNA levels. Introduction of EGFP-nWIP into these lines resulted in increased levels of WASP, up to normal. Two cell lines from patients with WAS mutations outside the WIP-binding domain did not show an increase of WASP after introduction of EGFP-nWIP.

Our results demonstrate that nWIP stabilizes WASP and ameliorates WASP levels in B cells from WAS patients with missesense mutations in the WBD of WASP. We will determine if nWIP will correct the functional defects in cells from these patients. (Supported by USPHS grant HL059561 and the PERKIN fund.)

WIP is critical for T cell responsiveness to IL-2 (33.1)

The WASP-interacting protein WIP stabilizes WASP, the product of the gene mutated in Wiskott-Aldrich syndrome. WIP-deficient T cells have low WASP levels, limiting the usefulness of WIP KO mice in defining the role of WIP in T cell function. To define this role, we compared WIP/WASP double knockout (DKO) mice to WASP KO mice on DO11.10 background. T cell development was normal in both strains, but peripheral T cell numbers were significantly decreased in DKO mice. WASP KO T cells proliferated and secreted IL-2 normally in response to OVA peptide (OVAp). In contrast, T cells from DKO mice proliferated poorly in response to OVAp in vitro and cutaneous hapten hypersensitivity was deficient in these mice. DKO T cells up-regulated CD25 expression and secreted normal amounts of IL-2 after antigen stimulation, but had defective response to IL-2, evidenced by failure to further up-regulate CD25 expression, phosphorylate STAT5, and induce expression of STAT5 dependent genes. DKO, but not WASP KO, T cells had a disrupted subcortical actin cytoskeleton and impaired actin polymerization following TCR ligation. These results indicate that WIP is essential for IL-2 signaling and responsiveness in T cells, possibly because of its critical role in TCR-triggered actin cytoskeletal reorganization.

A novel anti-WIP monoclonal antibody detects an isoform of WIP that lacks the WASP binding domain

The majority of Wiskott-Aldrich syndrome protein (WASP) in T cells is in a complex with WASP interacting protein (WIP), a 503 a.a. long proline rich protein. Here we demonstrate that a novel anti-WIP mAb, 3D10, recognizes an epitope in the N-terminal domain of the WIP protein, within the sequence 13PTFALA18. mAb 3D10 competes with actin, but not with WASP or Nck, for WIP binding. Analysis of 3D10 immunoprecipitates failed to demonstrate dissociation of the WASP-WIP complex after TCR ligation that we previously reported using a polyclonal anti-WIP anti-serum raised against a C-terminal peptide (a.a. 459-503) that spanned the WASP binding site. 3D10 mAb allowed the detection of a novel isoform of WIP consisting of a truncated 403 a.a. long protein that includes the 377 a.a. encoded by the first 4 exons of WIP followed by a 26 a.a. sequence encoded by intron 4.

Defective nuclear translocation of nuclear factor of activated T cells and extracellular signal-regulated kinase underlies deficient IL-2 gene expression in Wiskott-Aldrich syndrome

BACKGROUND

Proliferation and IL-2 production in response to T-cell receptor ligation are impaired in patients with Wiskott-Aldrich syndrome (WAS). The transcription factors nuclear factor-kappaB (NF-kappaB), nuclear factor of activated T cells (NF-AT), and activating protein-1 (AP-1) play a critical role in IL-2 gene expression.

OBJECTIVE

To investigate the mechanisms of impaired IL-2 production after T-cell receptor ligation in T cells deficient in WAS protein (WASP).

METHODS

T cells from WASP-/- mice were stimulated with anti-CD3 and anti-CD28. Nuclear NF-kappaB, NF-AT, and AP-1 DNA-binding activity was examined by electroshift mobility assay. NF-ATp dephosphorylation and nuclear localization were examined by Western blot and indirect immunofluorescence. Phosphorylation of the mitogen-activated protein kinases Erk and Jnk, and of their nuclear substrates Elk-1 and c-Jun, was examined by Western blot. Expression of mRNA for IL-2 and the NF-kappaB-dependent gene A20 and of the AP-1 components c-fos and c-Jun was examined by quantitative RT-PCR.

RESULTS

Nuclear translocation and activity of NF-kappaB were normal in T cells from WASP-/- mice. In contrast, NF-ATp dephosphorylation and nuclear localization, nuclear AP-1 binding activity, and expression of c-fos, but not c-Jun, were all impaired. Phosphorylation of Jnk, c-Jun, and Erk were normal. However, nuclear translocation of phosphorylated Erk and phosphorylation of its nuclear substrate Elk1, which activates the c-fos promoter, were impaired.

CONCLUSION

These results suggest that WASP is essential for NF-ATp activation, and for nuclear translocation of p-Erk, Elk1 phosphorylation, and c-fos gene expression in T cells. These defects underlie defective IL-2 expression and T-cell proliferation in WAS.