Characterization of Expanded Gamma Delta T Cells from Atypical X-SCID Patient Reveals Preserved Function and IL2RG-Mediated Signaling.

Abnormally high γδ T cell numbers among individuals with atypical SCID have been reported but detailed immunophenotyping and functional characterization of these expanded γδ T cells are limited. We have previously reported atypical SCID phenotype caused by hypomorphic IL2RG (NM_000206.3) c.172C > T;p.(Pro58Ser) variant. Here, we have further investigated the index patient's abnormally large γδ T cell population in terms of function and phenotype by studying IL2RG cell surface expression, STAT tyrosine phosphorylation and blast formation in response to interleukin stimulation, immunophenotyping, TCRvγ sequencing, and target cell killing. In contrast to his âºß T cells, the patient's γδ T cells showed normal IL2RG cell surface expression and normal or enhanced IL2RG-mediated signaling. Vδ2 + population was proportionally increased with a preponderance of memory phenotypes and high overall tendency towards perforin expression. The patient's γδ T cells showed enhanced cytotoxicity towards A549 cancer cells. His TCRvγ repertoire was versatile but sequencing of IL2RG revealed a novel c.534C > A; p.(Phe178Leu) somatic missense variant restricted to γδ T cells. Over time this variant became predominant in γδ T cells, though initially present only in part of them. IL2RG-Pro58Ser/Phe178Leu variant showed higher cell surface expression compared to IL2RG-Pro58Ser variant in stable HEK293 cell lines, suggesting that somatic p.(Phe178Leu) variant may at least partially rescue the pathogenic effect of germline p.(Pro58Ser) variant. In conclusion, our report indicates that expansion of γδ T cells associated with atypical SCID needs further studying and cannot exclusively be deemed as a homeostatic response to low numbers of conventional T cells.

STAT3 gain-of-function mutations connect leukemia with autoimmune disease by pathological NKG2Dhi CD8+ T cell dysregulation and accumulation.

The association between cancer and autoimmune disease is unexplained, exemplified by T cell large granular lymphocytic leukemia (T-LGL) where gain-of-function (GOF) somatic STAT3 mutations correlate with co-existing autoimmunity. To investigate whether these mutations are the cause or consequence of CD8+ T cell clonal expansions and autoimmunity, we analyzed patients and mice with germline STAT3 GOF mutations. STAT3 GOF mutations drove the accumulation of effector CD8+ T cell clones highly expressing NKG2D, the receptor for stress-induced MHC-class-I-related molecules. This subset also expressed genes for granzymes, perforin, interferon-γ, and Ccl5/Rantes and required NKG2D and the IL-15/IL-2 receptor IL2RB for maximal accumulation. Leukocyte-restricted STAT3 GOF was sufficient and CD8+ T cells were essential for lethal pathology in mice. These results demonstrate that STAT3 GOF mutations cause effector CD8+ T cell oligoclonal accumulation and that these rogue cells contribute to autoimmune pathology, supporting the hypothesis that somatic mutations in leukemia/lymphoma driver genes contribute to autoimmune disease.

Autoimmunity, hypogammaglobulinemia, lymphoproliferation, and mycobacterial disease in patients with activating mutations in STAT3.

The signal transducer and activator of transcription (STAT) family of transcription factors orchestrate hematopoietic cell differentiation. Recently, mutations in STAT1, STAT5B, and STAT3 have been linked to development of immunodysregulation polyendocrinopathy enteropathy X-linked-like syndrome. Here, we immunologically characterized 3 patients with de novo activating mutations in the DNA binding or dimerization domains of STAT3 (p.K392R, p.M394T, and p.K658N, respectively). The patients displayed multiorgan autoimmunity, lymphoproliferation, and delayed-onset mycobacterial disease. Immunologically, we noted hypogammaglobulinemia with terminal B-cell maturation arrest, dendritic cell deficiency, peripheral eosinopenia, increased double-negative (CD4(-)CD8(-)) T cells, and decreased natural killer, T helper 17, and regulatory T-cell numbers. Notably, the patient harboring the K392R mutation developed T-cell large granular lymphocytic leukemia at age 14 years. Our results broaden the spectrum of phenotypes caused by activating STAT3 mutations, highlight the role of STAT3 in the development and differentiation of multiple immune cell lineages, and strengthen the link between the STAT family of transcription factors and autoimmunity.

Skin reactions during anti-TNFα therapy for pediatric inflammatory bowel disease: a 2-year prospective study.

BACKGROUND: Although the development of therapy-related skin reactions is common along with an increase in the number of adult patients receiving anti-TNFα, there are few studies on pediatric inflammatory bowel disease; hence, this prospective study focuses on skin reactions related to infliximab therapy. METHODS: All pediatric patients with inflammatory bowel disease undergoing infliximab therapy were prospectively screened for the presence of skin manifestations at the time of each infusion between March 1, 2011 and March 31, 2011 at Children's Hospital, Helsinki, Finland. Blood inflammatory markers and fecal calprotectin levels were measured at the time of infusions. RESULTS: During the study period, 84 children with inflammatory bowel disease (Crohn's n = 64) received infliximab infusions (the median duration of therapy 12.2 mo). Almost every other patient (n = 40; 47.6%) presented chronic skin reactions, 23% with lesions considered severe. Most commonly, the patient's ear lobes and scalp were affected with psoriasis-like manifestations, followed by their eyelids, perioral and pubic area, trunk, and the extremities. However, an HLA-Cw*0602 genotype associating with psoriasis was rare. Interestingly, most patients with skin reactions had a low degree of intestinal inflammation based on their fecal calprotectin levels (median level, 133 µg/g versus 589 in unaffected patients; P < 0.016). Seven patients (8.3% of all patients but 17% of those with skin lesions) discontinued the given therapy due to a skin reaction. CONCLUSIONS: Skin reactions are common during maintenance therapy with infliximab in pediatric patients. For most patients, skin reactions seem to correlate with a low level of intestinal inflammation. Although potentially harsh, skin lesions mostly allow continuation of infliximab.

Orofacial granulomatosis in children--a challenge for diagnosis and treatment.

The data on orofacial granulomatosis, OFG, in children are sparse. We describe here 8 pediatric patients presenting with OFG, 2 of these cases associating with Crohn's disease. Therapeutic agents included systemic immunosuppressants such as glucocorticoids, methotrexate, anti-TNF-alpha agent, dapsone, antibiotics (metronidazole), and local treatment with topical tacrolimus or intralesional injections of triamcinolone hexacetonide. The treatment response ranged from good to poor results. The number of young patients suffering from OFG is not currently known and there are no gold standards for treatment. Thus, prospective follow-up studies on these patients are needed to gain more experience of the therapeutic responses.