Germline TET2 loss of function causes childhood immunodeficiency and lymphoma.

Molecular dissection of inborn errors of immunity can help to elucidate the nonredundant functions of individual genes. We studied 3 children with an immune dysregulation syndrome of susceptibility to infection, lymphadenopathy, hepatosplenomegaly, developmental delay, autoimmunity, and lymphoma of B-cell (n = 2) or T-cell (n = 1) origin. All 3 showed early autologous T-cell reconstitution following allogeneic hematopoietic stem cell transplantation. By whole-exome sequencing, we identified rare homozygous germline missense or nonsense variants in a known epigenetic regulator of gene expression: ten-eleven translocation methylcytosine dioxygenase 2 (TET2). Mutated TET2 protein was absent or enzymatically defective for 5-hydroxymethylating activity, resulting in whole-blood DNA hypermethylation. Circulating T cells showed an abnormal immunophenotype including expanded double-negative, but depleted follicular helper, T-cell compartments and impaired Fas-dependent apoptosis in 2 of 3 patients. Moreover, TET2-deficient B cells showed defective class-switch recombination. The hematopoietic potential of patient-derived induced pluripotent stem cells was skewed toward the myeloid lineage. These are the first reported cases of autosomal-recessive germline TET2 deficiency in humans, causing clinically significant immunodeficiency and an autoimmune lymphoproliferative syndrome with marked predisposition to lymphoma. This disease phenotype demonstrates the broad role of TET2 within the human immune system.

Levels of different subtypes of tumour-infiltrating lymphocytes correlate with each other, with matched circulating lymphocytes, and with survival in breast cancer.

PURPOSE: Breast cancer tumour-infiltrating lymphocytes associate with clinico-pathological factors, including survival, although the literature includes many conflicting findings. Our aim was to assess these associations for key lymphocyte subtypes and in different tumour compartments, to determine whether these provide differential correlations and could, therefore, explain published inconsistencies. Uniquely, we also examine whether infiltrating levels merely reflect systemic lymphocyte levels or whether local factors are predominant in recruitment. METHODS: Immunohistochemistry was used to detect tumour-infiltrating CD20+ (B), CD4+ (helper T), CD8+ (cytotoxic T) and FoxP3+ (regulatory T) cells in breast cancers from 62 patients, with quantification in tumour stroma, tumour cell nests, and tumour margins. Levels were analysed with respect to clinico-pathological characteristics and matched circulating levels (determined by flow-cytometry). RESULTS: CD4+ lymphocytes were the most prevalent subtype in tumour stroma and at tumour edge and CD8+ lymphocytes were most prevalent in tumour nests; FoxP3+ lymphocytes were rarest in all compartments. High grade or hormone receptor negative tumours generally had significantly increased lymphocytes, especially in tumour stroma. Only intra-tumoural levels of CD8+ lymphocytes correlated significantly with matched circulating levels (p < 0.03), suggesting that recruitment is mainly unrelated to systemic activity. High levels of stromal CD4+ and CD20+ cells associated with improved survival in hormone receptor negative cases (p < 0.04), while tumour nest CD8+ and FoxP3+ cells associated with poor survival in hormone receptor positives (p < 0.005). CONCLUSIONS: Lymphocyte subtype and location define differential impacts on tumour biology, therefore, roles of tumour-infiltrating lymphocytes will only be unravelled through thorough analyses that take this into account.

Reduced human transitional B cell T1/T2 ratio is associated with subsequent deterioration in renal allograft function.

Human transitional B cells express relatively high IL-10 and low TNF-α levels, which correlate with B regulatory activity in vitro. Herein, we aim to further define B regulatory phenotype and determine whether B regulatory activity can serve as a prognostic marker for renal allograft dysfunction (graft loss or 2-fold fall in estimated glomerular filtration rate). Transitional B cells can be divided into T1 and T2 subsets based on surface phenotype. T1 cells express a significantly higher ratio of IL-10 to TNF-α than T2 cells or other B subsets. When analyzed in 45 kidney transplant recipients at the time of late for-cause biopsy, the T1/T2 ratio was independently associated with allograft dysfunction over the next 5 years. Next, the T1/T2 ratio was examined in an independent set of 97 clinically stable kidney transplant recipients 2 years after transplant. Again, the T1/T2 ratio was strongly and independently associated with allograft dysfunction over the ensuing 5 years. In these clinically quiescent patients, a low T1/T2 ratio identified a 41-patient subgroup in which 35% developed allograft dysfunction, with 25% losing their allografts. However, none of the 56 patients with a high ratio developed graft dysfunction. In both the initial study and validation groups, the T1/T2 ratio was a much stronger predictor of graft dysfunction than donor-specific antibodies or the estimated glomerular filtration rate. Thus, the T1/T2 ratio, a relative measure of expressing an anti-inflammatory cytokine profile, is a novel prognostic marker that might inform individualized immunosuppression.

Lymphocyte depletion and repopulation after chemotherapy for primary breast cancer.

BACKGROUND: Approximately 30 % of breast cancer patients receive chemotherapy, yet little is known about influences of current regimens on circulating lymphocyte levels and phenotypes. Similarly, clinico-pathological factors that modify these influences, and implications for future immune health remain mainly unexplored. METHODS: We used flow-cytometry to assess circulating lymphocyte levels and phenotypes in 88 primary breast cancer patients before chemotherapy and at time-points from 2 weeks to 9 months after chemotherapy completion. We examined circulating titres of antibodies against pneumococcal and tetanus antigens using ELISAs. RESULTS: Levels of B, T and NK cells were significantly reduced 2 weeks after chemotherapy (p < 0.001). B cells demonstrated particularly dramatic depletion, falling to 5.4 % of pre-chemotherapy levels. Levels of all cells recovered to some extent, although B and CD4(+) T cells remained significantly depleted even 9 months post-chemotherapy (p < 0.001). Phenotypes of repopulating B and CD4(+) T cells were significantly different from, and showed no sign of returning to pre-chemotherapy profiles. Repopulating B cells were highly depleted in memory cells, with proportions of memory cells falling from 38 % to 10 % (p < 0.001). Conversely, repopulating CD4(+) T cells were enriched in memory cells, which increased from 63 % to 75 % (p < 0.001). Differences in chemotherapy regimen and patient smoking were associated with significant differences in depletion extent or repopulation dynamics. Titres of anti-pneumococcal and anti-tetanus antibodies were both significantly reduced post-chemotherapy and did not recover during the study (p < 0.001). CONCLUSION: Breast cancer chemotherapy is associated with long-term changes in immune parameters that should be considered during clinical management.

Immunologic human renal allograft injury associates with an altered IL-10/TNF-α expression ratio in regulatory B cells.

Human B cells with immunoregulatory properties in vitro (Bregs) have been defined by the expression of IL-10 and are enriched in various B-cell subsets. However, proinflammatory cytokine expression in B-cell subsets is largely unexplored. We examined the cytokine profiles of human PBMCs and found that subsets of CD24(hi)CD38(hi) transitional B cells (TrBs), CD24(hi)CD27(+) memory B cells, and naïve B cells express IL-10 and the proinflammatory cytokine TNF-α simultaneously. TrBs had the highest IL-10/TNF-α ratio and suppressed proinflammatory helper T cell 1 (Th1) cytokine expression by autologous T cells in vitro more potently than memory B cells did, despite similar IL-10 expression. Whereas neutralization of IL-10 significantly inhibited TrB-mediated suppression of autologous Th1 cytokine expression, blocking TNF-α increased the suppressive capacity of both memory and naïve B-cell subsets. Thus, the ratio of IL-10/TNF-α expression, a measure of cytokine polarization, may be a better indicator of regulatory function than IL-10 expression alone. Indeed, compared with TrB cells from patients with stable kidney graft function, TrBs from patients with graft rejection displayed similar IL-10 expression levels but increased TNF-α expression (i.e., reduced IL-10/TNF-α ratio), did not inhibit in vitro expression of Th1 cytokines by T cells, and abnormally suppressed expression of Th2 cytokines. In patients with graft dysfunction, a low IL-10/TNF-α ratio in TrBs associated with poor graft outcomes after 3 years of follow-up. In summary, these results indicate that B cell-mediated immune regulation is best characterized by the cytokine polarization profile, a finding that was confirmed in renal transplant patients.

CVID patients with autoimmunity have elevated T cell expression of granzyme B and HLA-DR and reduced levels of Treg cells.

AIMS: Common variable immunodeficiency (CVID) is a primary antibody immunodeficiency with approximately 20% of patients reporting additional autoimmune symptoms. The primary aim of this study was to compare the levels of activated and regulatory T cells (Treg cells) in CVID patients in an attempt to clarify their possible interactions leading to the generation of autoimmunity. METHODS: Immunophenotyping of T cells was performed by flow cytometry using a whole blood approach. Surface expression of human leukocyte antigen HLA class II DR and intracellular levels of granzyme B in T cell subsets were assessed; Treg levels were measured using CD4 CD25, FOXp3 and CTLA-4. RESULTS: CVID patients had higher levels of granzyme B and HLA-DR on CD8(+) T cells compared with control values (mean of 59% vs 30% and 45% vs 21%, respectively). Patients also had reduced levels of Treg cells compared with control values (con mean=3.24% vs pat=2.54%). Patients with autoimmunity (5/23) had a similar level of T cell activation markers to the rest of the patients but with lower Treg cells (mean of 1.1%) and reduced CD25 and CTLA-4 expression. Patients with autoimmunity had a higher ratio of activated to Treg cells compared with patients with no autoimmune symptoms. CONCLUSIONS: These results highlight that reduced levels of Treg cells were associated with elevated levels of activated T cells, suggesting that reduced Treg cells in these patients may have functional consequences in allowing exaggerated T cell responses.

Perioperative reductions in circulating lymphocyte levels predict wound complications after excisional breast cancer surgery.

OBJECTIVE: Postoperative wound complications after excisional surgery for primary breast cancer can result in patients requiring additional treatments and delay adjuvant therapy and are associated with worse prognoses.We investigated factors that might predispose patients to wound complications. BACKGROUND: A number of patient characteristics have been associated with wound complications, but there is currently no quantitative measure of the risk of their occurrence. Our hypothesis was that wound complications are related, in part, to the immune status of patients. METHODS: We recruited patients undergoing surgery for primary breast cancer and determined their circulating levels of various immune cells shortly before and after surgery as a measure of immune status. RESULTS: One hundred seventeen patients were recruited; 16 (13.7%) developed wound complications. The following patient and tumor characteristics were associated with higher wound complication rates: diabetes (P = 0.02); larger tumors (T2/3 vs T1; P = 0.02); metastatic axillary nodes (P = 0.006). With respect to immune status, no significant differences in preoperative levels of circulating immune cells were detected between patients who developed wound complications and those who did not. However, patients who developed complications showed greater reductions in lymphocyte levels 4 hours postoperatively than those who did not (P <0.001). Multivariate analyses demonstrated that falls in lymphocyte levels of greater than 20% or 50% 4 hours postoperatively acted as a significant and independent predictor of wound complications (P < 0.005 and P < 0.0001,respectively). CONCLUSIONS: Perioperative changes in lymphocyte levels could provide a practical predictive marker for wound complications on which selective antibiotic prophylaxis could be based.

Frequency of Treg cells is reduced in CVID patients with autoimmunity and splenomegaly and is associated with expanded CD21lo B lymphocytes.

INTRODUCTION: Common variable immunodeficiency is a heterogeneous antibody deficiency syndrome with autoimmune and inflammatory complications in a significant proportion of patients. The study was designed to evaluate the role of T regulatory (Treg) cells in common variable immunodeficiency (CVID) patients with autoimmunity. METHODS: The number and frequency of Treg cells (CD4(+), CD25(hi), Foxp3(+)) were evaluated in patients and controls, and Foxp3 expression in different subgroups of CVID patients with common clinical manifestations was compared. RESULTS: CVID patients had significantly fewer Treg cells than controls, and low frequency of Treg cells was associated with expansion of CD21(lo) B cells in patients. Patients with autoimmunity had significantly reduced frequency but normal numbers of regulatory T cells, whilst patients with splenomegaly had significant reduction in frequency and number of regulatory T cells. CONCLUSION: Foxp3 is useful on its own or as an adjunct to classify CVID patients although the possibility of reduction in Treg cells as a secondary phenomenon cannot be excluded.

Human serum inactivates non-glycosylated but not glycosylated granulocyte colony stimulating factor by a protease dependent mechanism: significance of carbohydrates on the glycosylated molecule.

It has previously been reported that the biological activity of the human hematopoetic cytokine granulocyte colony stimulating factor (G-CSF) was reduced following incubation with human serum. The mechanism of action of serum has remained elusive although a number of possible mechanisms have been suggested including inactivation due to binding to the serum protein alpha(2)-macroglobulin (alpha(2)M) and degradation by serum proteases. The aim of this study was to clarify the conditions required by serum to reduce the biological activity of the cytokine and to define the mechanism involved. It has also been noted that G-CSF obtained from a CHO expression system (and therefore considered a glycosylated molecule) was resistant to serum inactivation unlike G-CSF obtained from an E. coli expression system (considered to be non-glycosylated). We used an enzymatic approach to remove the carbohydrate residues from glycosylated G-CSF and tested this material for its stability in serum. We additionally used a mutated G-CSF lacking glycosylation sites. We concluded that glycosylation was important in protecting against serum inactivation. We observed that serum reduced the biological activity of non-glycosylated G-CSF in a dose, and temperature dependent manner and deduced that the mechanism of action was dependent upon alpha(2)M bound serum protease enzymes.

The effect of pertussis whole cell and acellular vaccines on pulmonary immunology in an aerosol challenge model.

Recent clinical trials have shown that the new generation of acellular pertussis vaccines (Pa) can confer protection against whooping cough with negligible adverse reactions. We have compared the effects of pertussis whole cell and acellular vaccines on pulmonary immune responses after aerosol challenge in a murine model of infection. Mice were vaccinated with PBS, Pw or Pa and challenged with Bordetella pertussis by the aerosol route. Cytokine gene expression was analysed from lung tissue and cells; lung lymphocytes were re-stimulated in vitro and cytokines produced measured. The results obtained are consistent with the proposal that a strong Th-1 response is associated with bacterial clearance in both the non-vaccinated and Pw vaccinated mice. The acellular vaccine treated mice cleared the bacterial challenge (with an intermediate efficacy) in the presence of low levels of any of the cytokines assessed. This suggests that Pa protects via a Th-2 independent mechanism.

The significance of carbohydrates on G-CSF: differential sensitivity of G-CSFs to human neutrophil elastase degradation.

It has been reported recently that granulocyte-colony stimulating factor (G-CSF) is degraded upon exposure to human neutrophil elastase (HNE), and this has a negative effect on the ability of the cytokine to promote the in vitro proliferation and maturation of CD34+ cells. This has important implications on the possible in vivo role of elastase in providing negative feedback to granulopoiesis by the direct antagonism of G-CSF. The cytokine used in that study was expressed in Escherichia coli [and was nonglycosylated (NG)], unlike the naturally occurring cytokine, which is an O-linked glycoprotein. As a Chinese hamster ovary-derived (glycosylated) cytokine is available, we compared the susceptibility of NG and glycosylated G-CSF to elastase degradation by incubating the cytokines with HNE and assessing its impact by sodium dodecyl sulfate gel electrophoresis and bioassay. We confirmed the ability of elastase to degrade NG G-CSF in a time- and concentration-dependent manner and found this was associated with a reduction in biological activity of the cytokine. Glycosylated G-CSF, however, was more resistant to elastase degradation, although prolonged exposure did lead to degradation and decreased biological activity. The significance of sugar residues on glycosylated G-CSF in providing protection against the effects of elastase was investigated using enzymatically deglycosylated G-CSF and a mutated form of the G-CSF molecule that was expressed in yeast but was NG. The possible role of HNE in serum-induced inactivation of NG G-CSF was also considered.

Tumor-specific CTL kill murine renal cancer cells using both perforin and Fas ligand-mediated lysis in vitro, but cause tumor regression in vivo in the absence of perforin.

Kidney cancer is a devastating disease; however, biological therapies have achieved some limited success. The murine renal cancer Renca has been used as a model for developing new preclinical approaches to the treatment of renal cell carcinoma. Successful cytokine-based approaches require CD8(+) T cells, but the exact mechanisms by which T cells mediate therapeutic benefit have not been completely identified. After successful biological therapy of Renca in BALB/c mice, we generated CTLs in vitro using mixed lymphocyte tumor cultures. These CTL mediated tumor-specific H-2K(d)-restricted lysis and production of IFN-gamma, TNF-alpha, and Fas ligand (FasL) in response to Renca. CTL used both granule- and FasL-mediated mechanisms to lyse Renca, although granule-mediated killing was the predominant lytic mechanism in vitro. The cytokines IFN-gamma and TNF-alpha increased the sensitivity of Renca cells to CTL lysis by both granule- and FasL-mediated death pathways. Adoptive transfer of these anti-Renca CTL into tumor-bearing mice cured most mice of established experimental pulmonary metastases, and successfully treated mice were immune to tumor rechallenge. Interestingly, we were able to establish Renca-specific CTL from mice gene targeted for perforin (pfp(-/-)) mice. Although these pfp(-/-) CTL showed reduced cytotoxic activity against Renca, their IFN-gamma production in the presence of Renca targets was equivalent to that of wild-type CTL, and adoptive transfer of pfp(-/-) CTL was as efficient as wild-type CTL in causing regression of established Renca pulmonary metastases. Therefore, although granule-mediated killing is of paramount importance for CTL-mediated lysis in vitro, some major in vivo effector mechanisms clearly are independent of perforin.