Ultrasensitive Detection of Attomolar Protein Concentrations by Dropcast Single Molecule Assays.

Measurements of very low levels of biomolecules, including proteins and nucleic acids, remain a critical challenge in many clinical diagnostic applications due to insufficient sensitivity. While digital measurement methods such as Single Molecule Arrays (Simoa), or digital ELISA, have made significant advances in sensitivity, there are still many potential disease biomarkers that exist in accessible biofluids at levels below the detection limits of these techniques. To overcome this barrier, we have developed a simple strategy for single molecule counting, dropcast single molecule assays (dSimoa), that enables more target molecules to be counted through increased sampling efficiency and with a simpler workflow. In this approach, beads are simply dropcast onto a microscope slide and dried into a monolayer film for digital signal readout. The dSimoa platform achieves attomolar limits of detection, with an up to 25-fold improvement in sensitivity over Simoa, the current state of the art for ultrasensitive protein detection. Furthermore, due to its simple readout process and improved cost-effectiveness compared to existing digital bioassays, dSimoa increases amenability to integration into point-of-care platforms. As an illustration of the potential utility of dSimoa, we demonstrate its ability to measure previously undetectable levels of Brachyury, a tissue biomarker for chordoma, in plasma samples. With its significantly enhanced sensitivity and simplicity, dSimoa can pave the way toward the discovery of new biomarkers for early disease diagnosis and improved health outcomes.

The TH1 phenotype of follicular helper T cells indicates an IFN-γ-associated immune dysregulation in patients with CD21low common variable immunodeficiency.

BACKGROUND: A subgroup of patients with common variable immunodeficiency (CVID) experience immune dysregulation manifesting as autoimmunity, lymphoproliferation, and organ inflammation and thereby increasing morbidity and mortality. Therefore treatment of these complications demands a deeper comprehension of their cause and pathophysiology. OBJECTIVES: On the basis of the identification of an interferon signature in patients with CVID with secondary complications and a skewed follicular helper T-cell differentiation in defined monogenic immunodeficiencies, we sought to determine the profile of CD4 memory T cells in blood and secondary lymphatic tissues of these patients. METHODS: We quantified TH1/TH2/TH17 CD4 memory T cells in blood and lymph nodes of patients with CVID using flow cytometry, analyzed their function, and correlated all findings to the burden of immune dysregulation. RESULTS: Patients with CVID with immune dysregulation had a skewed memory CD4 T-cell differentiation toward a CXCR3+CCR6- TH1 phenotype both in blood and lymph nodes. Consistent with our phenotypic findings, we observed a higher IFN-γ production in peripheral CD4 memory T cells and lymph node-derived follicular helper T cells of patients with CVID compared with those of healthy control subjects. Increased IFN-γ production was accompanied by a poor germinal center output, an accumulation of T-box transcription factor (T-bet)+ B cells in lymph nodes, and an accumulation of T-bet+CD21low B cells in peripheral blood of affected patients. CONCLUSION: Identification of excessive IFN-γ production by blood and lymph node-derived T cells of patients with CVID with immune dysregulation will offer new therapeutic avenues for this subgroup. CD21low B cells might serve as a marker of this IFN-γ-associated dysregulation.

[Effects of sleep deprivation induced blood stasis syndrome on platelet activation in rats].

Blood stasis syndrome is the pre-state of thrombotic disease. The model of blood stasis syndrome in rats was induced by sleep deprivation to study on effects of blood stasis syndrome on platelet activation. The weight, the color of tongue and hemorheology for the blood stasis syndrome of Chinese medicine were measured after modeling. The release of platelet granules and platelet activation factors in plasma were detected by ELISA kit related indicators to provide experimental basis for platelet function evaluation and related drug effects in syndrome research. The results showed that the weight of the model group rats was significantly lower than that of the normal group (P<0.01). The tongue showed a dark purple blood stasis pattern, and the R, G and B values of the tongue surface in model group were significantly lower than those of the normal group (P<0.01). The hemorheological parameters including high shear, middle shear and low shear viscosity in whole blood were significantly higher than those in the normal group (P<0.01). But plasma viscosity did not change significantly. The release levels of platelet α particles (GMP-140, ß-TG, PF4) and dense particles (ADP, 5-HT) were significantly higher than those in the normal group (P<0.01). The levels of TXB2 and 6-keto-PGF1α in plasma were significantly higher than those in the normal group (P<0.01). The ratios of TXB2 and 6-keto-PGF2α were also significantly higher than those in the normal group (P<0.01). The levels of PAF in plasma in model group were significantly higher than those in the normal group (P<0.01). It was concluded that platelet functions could be changed induced by sleep deprivationin rats with blood stasis syndrome, and there might be inflammation and endothelial cell dysfunction.

[Antihypertensive effect and mechanism of Dendrobium officinale flos on high-blood pressure rats induced by high glucose and high fat compound alcohol].

This study aimed to investigate the antihypertensive effect and possible mechanism of Dendrobium officinale flos on hypertensive rats induced by high glucose and high fat compound alcohol. The hypertensive models were successfully made by high-glucose and high-fat diet, with gradient drinking for 4 weeks, and then divided into model control group, valsartan (5.7 mg·kg⁻¹) positive control group and D. officinale flos groups (3，1 g·kg⁻¹). After 6 weeks of treatment, the blood pressure of rats was measured regularly. After the last administration, endothelin-1 (ET-1), thromboxane B2 (TXB2), prostacyclin (PGI2) and nitric oxide (NO) were tested. Endothelial nitric oxide synthase (eNOS) expression and lesion status in thoracic aorta were detected. The vascular endothelium dependent dilation of the thoracic aorta was detected by the isolated vascular loop tension test. The results showed that D. officinale flos could significantly reduce systolic blood pressure and mean arterial pressure in hypertensive rats, inhibit the thickening of thoracic aorta and the loss of endothelial cells, reduce plasma content of ET-1 and TXB2, and increase the content of PGI2 and NO. After long-term administration, vascular endothelium dependent dilation of the thoracic aorta was significantly increased, and could be blocked by the eNOS inhibitor (L-NAME) and increase the expression of eNOS. Therefore, D. officinale flos has an obvious antihypertensive effect on high glucose and high fat compound alcohol-induced hypertensive rats. Its mechanism may be correlated with the improvement of vascular diastolic function by protecting vascular endothelial cells, and finally resist hypertension.

Adequate Th2-type response associates with restricted bacterial growth in latent mycobacterial infection of zebrafish.

Tuberculosis is still a major health problem worldwide. Currently it is not known what kind of immune responses lead to successful control and clearance of Mycobacterium tuberculosis. This gap in knowledge is reflected by the inability to develop sufficient diagnostic and therapeutic tools to fight tuberculosis. We have used the Mycobacterium marinum infection model in the adult zebrafish and taken advantage of heterogeneity of zebrafish population to dissect the characteristics of adaptive immune responses, some of which are associated with well-controlled latency or bacterial clearance while others with progressive infection. Differences in T cell responses between subpopulations were measured at the transcriptional level. It was discovered that a high total T cell level was usually associated with lower bacterial loads alongside with a T helper 2 (Th2)-type gene expression signature. At late time points, spontaneous reactivation with apparent symptoms was characterized by a low Th2/Th1 marker ratio and a substantial induction of foxp3 reflecting the level of regulatory T cells. Characteristic gata3/tbx21 has potential as a biomarker for the status of mycobacterial disease.

[The expression of triggering receptor expresses on myeloid cells receptor-1, T cell-specific transcription factor, and eomesodermin in Aspergillus infected immunosuppressed rats].

OBJECTIVE: To investigate the function of triggering receptor expresses on myeloid cells receptor-1 (TREM-1) in lymphocyte differentiation and regulation of Aspergillus infected immunosuppressed rats. METHODS: Cyclophosphamide (CTX) was intraperitoneally injected and Fumigatus spore suspension was inhaled by percutaneous tracheostomy to establish the immunosuppressive invasive pulmonary aspergillosis (IPA) rat model. After 24 h, 48 h, 72 h and 96 h inoculation, rats were sacrificed. Lung tissue specimens, bronchoalveolar lavage fluid (BALF), and plasma samples were collected. Plasma and BALF sTREM-1, plasma T cell-specific transcription factor (T-box expressed in T cells, T-bet) and eomesodermin(Eomes) were detected by ELISA. Biopsy specimens of lung tissue were used for periodic acid-schiff (PAS) staining and culture. RESULTS: The mortality rate of immunosuppressed rats after Aspergillus inhalation for 96 h was as high as 54.4%. Biopsy of lung tissue suggested acute inflammatory cell infiltration, interstitial lung congestion, alveolar structural damage, and visible Aspergillus hyphae in alveoli. Compared with normal control group[(110.50 ± 7.70) ng/L], plasma sTREM-1 in study groups were significantly increased[IPA: (146.77 ± 10.41) ng/L; CXT+ IPA at 24 h: (226.00 ± 11.88) ng/L; CTX+ IPA at 48 h: (200.77 ± 10.63) ng/L; P<0.05], so were T-bet levels[IPA: (561.17 ± 7.23) µg/L; CXT+ IPA at 24 h: (647.00 ± 33.03) µg/L; CTX+ IPA at 48 h: (619.23 ± 87.44) µg/L; control group: (340.03 ± 26.32) µg/L; respectively, P < 0.05]. However, plasma Eomes levels in IPA group, CTX+ IPA at 24 h and 48 h were significantly lower compared with that in normal controls[IPA: (7.96 ± 0.65) ng/L; CXT+ IPA at 24 h: (3.97 ± 0.35) ng/L; CTX+ IPA at 48 h: (4.00 ± 0.74) ng/L; control group: (8.38 ± 0.51) ng/L; respectively, P < 0.001]. Compared with those in CTX+ IPA vaccination after 24 h and 48 h, plasma sTREM-1 [(106.67 ± 7.64) ng/L; (133.27 ± 32.79) ng/L] and T-bet [(299.64 ± 63.07) µg/L; (398.02 ± 109.22) µg/L] in CTX+ IPA at 72 h and 96 h inoculation were significantly lower (P < 0.001). While Eomes [(8.38 ± 0.54) ng/L; (8.40 ± 0.70) ng/L]raised significantly higher (P < 0.001). Compared with the control group, sTREM-1 levels in BALF of IPA+ CTX 24 h, 48 h, 72 h, and 96 h groups were consistently high (P < 0.05). Pearson correlation analysis showed that sTREM-1 and T-bet had a significant positive correlation (r = 0.91, P < 0.001), yet Eomes was negatively correlated with them (r = -0.788, P < 0.001). CONCLUSIONS: sTREM-1 in rat plasma and BALF appears highly expressed in immune compromised Aspergillus infected rat model. Plasma sTREM-1 is closely correlated with T-bet and Eomes levels, which suggests that TREM-1 may be involved in lymphocytic regulation and differentiation during fungal infection.

Clinical expression of Holt-Oram syndrome on the basis of own clinical experience considering prenatal diagnosis.

OBJECTIVES: Holt-Oram syndrome manifests with defects of upper limbs, pectoral girdle and cardiovascular system. The aim of this paper was to present complex clinical picture of the syndrome and its variable expression on the example of the family diagnosed genetically on the neonatal ward, after proband's prenatal examination. MARETIAL AND METHODS: Nine family members were tested for TBX5 gene mutation. RESULTS: Four of family members were diagnosed with Holt-Oram syndrome and five had correct genetic test results. The diagnosis allowed to identify a genetic risk family and enabled to provide them with genetic counselling. CONCLUSIONS: Diagnosis of Holt-Oram syndrome is possible as early as in prenatal period and it can be verified by genetic tests.

Expansion of highly differentiated cytotoxic terminally differentiated effector memory CD8+ T cells in a subset of clinically stable kidney transplant recipients: a potential marker for late graft dysfunction.

Despite the effectiveness of immunosuppressive drugs, kidney transplant recipients still face late graft dysfunction. Thus, it is necessary to identify biomarkers to detect the first pathologic events and guide therapeutic target development. Previously, we identified differences in the T-cell receptor Vß repertoire in patients with stable graft function. In this prospective study, we assessed the long-term effect of CD8(+) T-cell differentiation and function in 131 patients who had stable graft function. In 45 of 131 patients, a restriction of TCR Vß diversity was detected and associated with the expansion of terminally differentiated effector memory (TEMRA; CD45RA(+)CCR7(-)CD27(-)CD28(-)) CD8(+) T cells expressing high levels of perforin, granzyme B, and T-bet. This phenotype positively correlated with the level of CD57 and the ability of CD8(+) T cells to secrete TNF-α and IFN-γ. Finally, 47 of 131 patients experienced kidney dysfunction during the median 15-year follow-up period. Using a Cox regression model, we found a 2-fold higher risk (P=0.06) of long-term graft dysfunction in patients who had increased levels of differentiated TEMRA CD8(+) T cells at inclusion. Collectively, these results suggest that monitoring the phenotype and function of circulating CD8(+) T cells may improve the early identification of at-risk patients.

Increased interleukin-27 promotes Th1 differentiation in patients with chronic immune thrombocytopenia.

Chronic immune thrombocytopenia (cITP) is an autoimmune disease with disturbed cytokine profile. Although plasma levels of IL-27 are shown to be associated with cITP, its association with T cell subsets has not been studied. The objective of this study was to study the association between IL-27 and different T cell subsets in patients with cITP. Heparinized blood was collected from 31 patients with cITP and 36 healthy controls (platelet count <100 × 10(9)/l and 103-280 × 10(9)/l, respectively). The percentage of Th1, Th2 and Th17 cells in peripheral blood mononuclear cells (PBMCs) were enumerated by flow cytometry, and the mRNA levels of IL-27, T-bet, GATA-3 and retinoid-related orphan receptor gamma (RORγt) by real-time reverse transcriptase polymerase chain (RT-PCR). Plasma cytokine levels of IL-27, interferon-gamma (IFN-γ), IL-4 and IL-17A were estimated by flow cytometrix. The effect of exogenous recombinant IL-27(rhIL-27) on the differentiation of T cells into Th1, Th2 and Th17 cells was investigated by cell culture. The percentage of Th1 and Th17 cells and the plasma concentration and mRNA levels of IL-27 were significantly higher in cITP patients compared with healthy controls. Plasma levels of IL-27 correlated positively with percentage of Th1 cells in patients with cITP. Exogenous (rhIL-27) could significantly up-regulate the percentage of Th1 cells and down-regulate Th2 cells in vitro. Th17 cells were reduced in the presence of (rhIL-27) in controls but had no effect in patients with cITP. The up-regulation of IL-27 might cause Th1 differentiation and might be involved in the pathophysiology of cITP.

Role of CD4(+) and CD8α(+) T cells in protective immunity against Edwardsiella tarda infection of ginbuna crucian carp, Carassius auratus langsdorfii.

Edwardsiella tarda is an intracellular pathogen that causes edwardsiellosis in fish. Our previous study suggests that cell-mediated immunity (CMI) plays an essential role in protection against E. tarda infection. In the present study, we adoptively transferred T-cell subsets sensitized with E. tarda to isogenic naïve ginbuna crucian carp to determination the T-cell subsets involved in protecting fish from E. tarda infection. Recipients of CD4(+) and CD8α(+) cells acquired significant resistance to infection with E. tarda 8 days after sensitization, indicating that helper T cells and cytotoxic T lymphocytes plays crucial roles in protective immunity to E. tarda. Moreover, transfer of sensitized CD8α(+) cells up-regulated the expression of genes encoding interferon-γ (IFN-γ) and perforin, suggesting that protective immunity to E. tarda involves cell-mediated cytotoxicity and interferon-γ-mediated induction of CMI. The results establish that CMI plays a crucial role in immunity against E. tarda. These findings provide novel insights into understanding the role of CMI to intracellular pathogens of fish.

The molecular signature of tissue resident memory CD8 T cells isolated from the brain.

Tissue resident memory (Trm) CD8 T cells represent a newly described memory T cell population. We have previously characterized a population of Trm cells that persists within the brain after acute virus infection. Although capable of providing marked protection against a subsequent local challenge, brain Trm cells do not undergo recall expansion after dissociation from the tissue. Furthermore, these Trm cells do not depend on the same survival factors as the circulating memory T cell pool as assessed either in vivo or in vitro. To gain greater insight into this population of cells, we compared the gene expression profiles of Trm cells isolated from the brain with those of circulating memory T cells isolated from the spleen after an acute virus infection. Trm cells displayed altered expression of genes involved in chemotaxis, expressed a distinct set of transcription factors, and overexpressed several inhibitory receptors. Cumulatively, these data indicate that Trm cells are a distinct memory T cell population disconnected from the circulating memory T cell pool and display a unique molecular signature that likely results in optimal survival and function within their local environment.

Research on the roles of transcription factors T-bet and GATA-3 in aplastic anemia.

BACKGROUND: Aplastic anemia (AA) is a type of bone marrow hematopoietic system disease. The immune mediated hematopoietic inhibition is recognized as the most common pathogenesis of AA. However, the roles of the T-bet/GATA-3-mediated cell immune disorder in aplastic anemia (AA) is still unknown. METHODS: Experimental samples were obtained from 27 patients with AA, including 15 cases of severe AA (SAA) and 12 cases of immune mediated AA (MAA), and 25 healthy volunteers (control group). The secretory levels of IFN-gamma and IL-4 cytokines were determined by ELISA. The mRNA expression levels of transcription factors T-bet, GATA-3, and FoxP3 were measured in PBMCs by RT-PCR. Th1, Th2, and T lymphocyte subsets were detected in peripheral blood by flow cytometry. RESULTS: Compared to the healthy control group, the expression of T-bet mRNA and the percentage of Th1-type cells in the AA group significantly increased (p < 0.01), while the expression of GATA-3 and FoxP3 mRNA and the percentage of Th2-type cells decreased sharply (p < 0.05, p < 0.01). Compared with MAA, the expression of T-bet mRNA and the percentage of Th1-type cells increased significantly in SAA (p < 0.01); meanwhile, the expression of GATA-3 mRNA and the proportion of Th2-type cells decreased noticeably (p < 0.05, p < 0.01). Particularly, the percentage of CD3+ and CD3+CD8+ T cells in the AA group increased (p < 0.05), while the percentage of CD3+CD4+, CD4+CD25+, and CD4+CD8+ cells decreased (p < 0.05, p < 0.01). CONCLUSIONS: Abnormal expression of the transcription factors T-bet and GATA-3 contributes to the imbalance of Thl/Th2 lymphocytes associated with immune dysfunction, leading to the development and progression of AA.

The role of upstream stimulatory factor 1 in the transcriptional regulation of the human TBX21 promoter mediated by the T-1514C polymorphism associated with systemic lupus erythematosus.

T-bet is a key regulator for the lineage commitment in CD4+ T helper (Th) 1 cells by activating the hallmark production of interferon-γ. Previously, two single nucleotide polymorphisms (SNPs) in the TBX21 promoter, T-1993C and T-1514C, have been shown by statistic studies to associate with systemic lupus erythematosus (SLE). The effect of -1993 SNP on the Yin Yang 1 transcription factor-mediated promoter activity has been already indicated. This study aimed to investigate roles of the T-1514C SNP on TBX21 transcription and its functional effect by luciferase reporter, electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP) assay, and flow cytometric analysis of intracellular T-bet, IFN-γ, and IL-4 expression in activated CD4+ T cells. The TBX21 promoter carrying -1514C possessed significantly lower transcriptional activity than that of -1514T and was markedly downregulated by the overexpression of upstream stimulatory factor 1 (USF-1) when compared with the promoter carrying -1514T. EMSA indicated that the transcription factor USF-1 was bound to the -1514C allele probe with the affinity higher than that to the -1514T allele probe. ChIP assay suggested that USF-1 bound around -1514 of TBX21 genomic DNA in vivo in the human T cell line Jurkat with -1514C/T. The individuals carrying -1514C allele were determined to have significantly diminished expression of T-bet and IFN-γ and increased IL-4 production in CD4+ T cells compared with those of -1514T allele. The findings demonstrate that the T-1514C polymorphism affects TBX21 gene expression and Th1 cytokine production by binding USF-1 to the SNP site.

CD4+T-bet+, CD4+pSTAT3+ and CD8+T-bet+ T cells accumulate in peripheral blood during NZB treatment.

Circulating T cells and monocytes expressing T-bet, pSTAT1 and pSTAT3 increase in relapsing-remitting multiple sclerosis (RRMS) during relapse. Natalizumab (NZB) is an effective drug in RRMS, but exacerbation of the disease after its discontinuation has been described in some patients. The aim of this research was to study the effect of NZB treatment on circulating lymphomonocyte subpopulations expressing T-bet, pSTAT1, pSTAT3 and CD4+CD25+Foxp3+ regulatory T cells. Flow cytometry was used to evaluate the percentages of circulating CD4+ and CD8+ T cells, CD14+ monocytes and B cells expressing T-bet, pSTAT1, and pSTAT3, and CD4+CD25+Foxp3+ regulatory T cells from RRMS patients before and after 6-12 NZB infusions. In NZB-treated RRMS patients, the percentages of CD4+pSTAT1+ and CD8+pSTAT1+ T cells, CD14+pSTAT1+ monocytes, CD4+T-bet+, CD8+T-bet+ and CD4+pSTAT3+ T cells and CD14+pSTAT3+ monocytes increased after 12 drug infusions and were similar to those observed in untreated relapsing RRMS patients. Otherwise in vitro NZB exposure of peripheral blood mononuclear cells from untreated RRMS patients and controls had no effect. It was concluded that NZB treatment determines an accumulation of CD4+pSTAT1+, CD8+pSTAT1+, CD4+T-bet+, CD8+T-bet+ and CD4+STAT3+ T cells in peripheral blood that may account for the exacerbation of the disease observed in some patients after the discontinuation of the drug.

Effect of non-surgical periodontal therapy on the levels of Th17/Th1/Th2 cytokines and their transcription factors in Chinese chronic periodontitis patients.

AIM: A new subset of CD4(+) T cells, Th17, has been recently discovered independent from Th1/Th2 paradigm. The aim of this study was to investigate the effects of non-surgical periodontal therapy on the expression of Th17/Th1/Th2 cytokines and transcription factors, and Th17 cell vibration in Chinese chronic periodontitis patients. MATERIALS AND METHODS: The levels of Th17/Th1/Th2 cytokines (IL-17, IL-21/IFN-γ/IL-4) in gingival crevicular fluid from 30 chronic periodontitis patients before and after treatment were determined by ELISA. The expression of transcription factors (RORC, T-bet and GATA-3) in peripheral blood was measured by real-time PCR, and the levels of Th17 cells in CD4(+) T cells were determined by flow cytometry. RESULTS: After treatment, the levels of IL-17 and IL-21 were down-regulated (P<0.05), and IL-4 was increased (P<0.05), but there were no differences in the level of IFN-γ (P>0.05). Correspondingly, the expression of RORC was decreased 1.99-fold (P<0.05), and GATA-3 was increased 1.76-fold (P<0.05). However, there were no differences in the level of T-bet (P>0.05). Moreover, the quantity of Th17 cells in peripheral blood was decreased (P<0.05), especially IL-17(+) IFN-γ(+) subgroup. CONCLUSIONS: These results suggest that Th17 cells play a destructive role in the immune balance of periodontitis, and the effect of Th1 cells is not significant, while Th2 cells have a protective effect.

Characterization of KIR + NKG2A + Eomes- NK-like CD8+ T cells and their decline with age in healthy individuals.

BACKGROUND: KIR+NKG2A + Eomes+ CD8+ T cells, which are preferentially found with a TEMRA (CD45RA + CCR7-) phenotype while having the capacity to rapidly produce IFN-γ in response to innate stimulation (IL-12 and IL-18), have been demonstrated to exist in human cord blood and the adult blood circulation. This highly responsive T-cell type was termed NK-like CD8+ T cells due to their capability to act in an innate immune fashion in mice similar to NK cells. However, KIR+NKG2A + CD8+ T cells that are Eomes- represent a small proportion of unconventional T cells that have not been described until now. METHODS: We compare the distribution of the memory phenotypes and senescence-associated markers of two T-cell subsets by multicolor flow cytometry in 10 cord blood samples and 105 healthy individuals (HIs) ranging from 6 to 84 years of age. RESULTS: We found that the Eomes+ population has a higher differentiation degree than the Eomes- population. T cells in the Eomes- subset show proportionally less TEMRA phenotypes while instead preferentially displaying a more naïve and TCM phenotype. Furthermore, the Eomes- population was shown to linearly decrease with age, while the Eomes+ population exhibited more senescence-associated characteristics, such as CD57 expression and loss of CD28. CONCLUSION: Overall, the KIR+NKG2A + Eomes- CD8+ T-cell population shares similar characteristics with the Eomes+ population, although with a lower degree of differentiation, lower senescence marker expression, and a proportional decrease with age. Thus, we suspect that KIR+NKG2A + Eomes-CD8+ T cells may represent a less differentiated stage of the NK-like CD8+ T-cell subset.

SARS-CoV-2 spike-specific memory B cells express higher levels of T-bet and FcRL5 after non-severe COVID-19 as compared to severe disease.

SARS-CoV-2 infection elicits a robust B cell response, resulting in the generation of long-lived plasma cells and memory B cells. Here, we aimed to determine the effect of COVID-19 severity on the memory B cell response and characterize changes in the memory B cell compartment between recovery and five months post-symptom onset. Using high-parameter spectral flow cytometry, we analyzed the phenotype of memory B cells with reactivity against the SARS-CoV-2 spike protein or the spike receptor binding domain (RBD) in recovered individuals who had been hospitalized with non-severe (n = 8) or severe (n = 5) COVID-19. One month after symptom onset, a substantial proportion of spike-specific IgG+ B cells showed an activated phenotype. In individuals who experienced non-severe disease, spike-specific IgG+ B cells showed increased expression of markers associated with durable B cell memory, including T-bet and FcRL5, as compared to individuals who experienced severe disease. While the frequency of T-bet+ spike-specific IgG+ B cells differed between the two groups, these cells predominantly showed an activated switched memory B cell phenotype in both groups. Five months post-symptom onset, the majority of spike-specific memory B cells had a resting phenotype and the percentage of spike-specific T-bet+ IgG+ memory B cells decreased to baseline levels. Collectively, our results highlight subtle differences in the B cells response after non-severe and severe COVID-19 and suggest that the memory B cell response elicited during non-severe COVID-19 may be of higher quality than the response after severe disease.

Homeostatic regulation of T effector to Treg ratios in an area of seasonal malaria transmission.

An important aspect of clinical immunity to malaria is the ability to down-regulate inflammatory responses, once parasitaemia is under control, in order to avoid immune-mediated pathology. The role of classical (CD4(+)CD25(+)CD127(lo/-)FOXP3(+)) Treg in this process, however, remains controversial. Thus, we have characterized the frequency, phenotype and function of Treg populations, over time, in healthy individuals in The Gambia. We observed that both the percentage and the absolute number of CD4(+)FOXP3(+)CD127(lo/-) T cells were higher among individuals living in a rural village with highly seasonal malaria transmission than among individuals living in an urban area where malaria rarely occurs. These CD4(+)FOXP3(+)CD127(lo/-) T cells exhibited an effector memory and apoptosis-prone phenotype and suppressed cytokine production in response to malaria antigen. Cells from individuals exposed to malaria expressed significantly higher levels of mRNA for forkhead box P3 and T-box 21 (T-BET) at the end of the malaria transmission season than at the end of the non-transmission season. Importantly, the ratio of T-BET to forkhead box P3 was remarkably consistent between populations and over time, indicating that in healthy individuals, a transient increase in Th1 responses during the malaria transmission season is balanced by a commensurate Treg response, ensuring that immune homeostasis is maintained.

IFN-gamma-STAT1 signal regulates the differentiation of inducible Treg: potential role for ROS-mediated apoptosis.

Regulatory CD4(+) T cells are important for the homeostasis of immune cells, and their absence correlates with autoimmune disorders. However, how the immune system regulates Treg homeostasis remains unclear. We found that IFN-gamma-deficient-mice had more forkhead box P3 (FOXP3(+)) cells than WT mice in all secondary lymphoid organs except the thymus. However, T-bet- or IL-4Ralpha-deficient mice did not show a similar increase. In vitro differentiation studies showed that conversion of naïve T cells into FOXP3(+) cells (neo-generated inducible Treg (iTreg)) by TGF-beta was significantly inhibited by IFN-gamma in a STAT-1-dependent manner. Moreover, an in vivo adoptive transfer study showed that inhibition of FOXP3(+) iTreg generation by IFN-gamma was a T-cell autocrine effect. This inhibitory effect of IFN-gamma on iTreg generation was significantly abrogated after N-acetyl-L-cysteine treatment both in vitro and in vivo, indicating that IFN-gamma regulation of iTreg generation is dependent on ROS-mediated apoptosis. Therefore, our results suggest that autocrine IFN-gamma can negatively regulate the neo-generation of FOXP3(+) iTreg through ROS-mediated apoptosis in the periphery.

Quantification of fetal DNA by use of methylation-based DNA discrimination.

BACKGROUND: Detection of circulating cell-free fetal nucleic acids in maternal plasma has been used in noninvasive prenatal diagnostics. Most applications rely on the qualitative detection of fetal nucleic acids to determine the genetic makeup of the fetus. This method leads to an analytic dilemma, because test results from samples that do not contain fetal DNA or are contaminated with maternal cellular DNA can be misleading. We developed a multiplex approach to analyze regions that are hypermethylated in placenta relative to maternal blood to evaluate the fetal portion of circulating cell-free DNA isolated from maternal plasma. METHODS: The assay used methylation-sensitive restriction enzymes to eliminate the maternal (unmethylated) fraction of the DNA sample. The undigested fetal DNA fraction was then coamplified in the presence of a synthetic oligonucleotide to permit competitive PCR. The amplification products were quantified by single-base extension and MALDI-TOF MS analysis. RESULTS: Using 2 independent markers, (sex determining region Y)-box 14 (SOX14) and T-box 3 (TBX3), we measured a mean of 151 copies of fetal DNA/mL plasma and a mean fetal fraction of 0.13 in samples obtained from pregnant women. We investigated 242 DNA samples isolated from plasma from pregnant and nonpregnant women and observed an analytical sensitivity and specificity for the assay of 99% and 100%, respectively. CONCLUSIONS: By investigating several regions in parallel, we reduced the measurement variance and enabled quantification of circulating cell-free DNA. Our results indicate that this multiplex methylation-based reaction detects and quantifies the amount of fetal DNA in a sample isolated from maternal plasma.