Validation of the NUT CRACKER Diagnostic Algorithm and Prediction for Cashew and Pistachio Co-Allergy.

BACKGROUND: Because of the high cross-sensitization among tree nuts, the NUT CRACKER (Nut Co-reactivity-Acquiring Knowledge for Elimination Recommendations) study proposed a diagnostic algorithm to minimize the number of required oral food challenges (OFCs). OBJECTIVE: To validate the algorithm for cashew and pistachio allergy and determine markers for allergic severity. METHODS: Patients (n = 125) with a median age of 7.8 (interquartile range, 5.9-11.2) years with suspected tree nut allergy were evaluated prospectively with decision tree points on the basis of skin prick test (SPT), basophil activation test (BAT), and knowledge of the coincidence of allergies. Validation of allergic status was determined by OFC. Markers of clinical severity were evaluated using the combined original and prospective cohort (n = 187) in relationship to SPT, BAT, and Ana o 3-sIgE. RESULTS: Reactivity to cashew in SPT, BAT, and Ana o 3-sIgE and the incidence of abdominal pain on challenge were significantly higher in dual-allergic cashew/pistachio patients (n = 82) versus single cashew allergic patients (n = 18) (P = .001). All 3 diagnostic tests showed significant inverse correlation with log10 reaction doses for positive cashew OFC. The algorithm reduced overall the total number of OFCs by 72.0%, with a positive predictive value and negative predictive value of 93.0% and 99.0%, respectively. Cashew false-positives were observed primarily in hazelnut-allergic patients (P = .026). In this population, Ana o 3-specific IgE could diagnose cashew allergy with a sensitivity of more than 90% and a specificity of more than 95%. CONCLUSIONS: The NUT CRACKER diagnostic algorithm was validated and reduced the number of diagnostic OFCs required. Markers for severity phenotypes may guide oral immunotherapy protocols, improving the risk/benefit ratio for patients.

Cashew oral immunotherapy for desensitizing cashew-pistachio allergy (NUT CRACKER study).

BACKGROUND: Oral immunotherapy (OIT) is a treatment option for patients with milk, egg, and peanut allergy, but data on the efficacy and safety of cashew OIT are limited. METHODS: A cohort of 50 cashew-allergic patients aged ≥4 years, who were consecutively enrolled into cashew OIT (target dose 4000 mg protein) between 4/2016 and 12/2019. Fifteen cashew-allergic patients who continued cashew elimination served as observational controls. Co-allergy to pistachio and walnut was determined. Full desensitization rate and associated immunological changes in both groups were compared. Patients fully desensitized to cashew were instructed to consume a dose of 1200 mg cashew protein for 6 months and were then challenged to a full dose. Patients with co-allergy to pistachio or walnut were challenged to the respective nut. RESULTS: Forty-four of 50 OIT-treated patients (88%) compared to 0% in controls tolerated a dose of 4000 mg cashew protein at the end of the study (odds ratio 8.3, 95% CI 3.9-17.7, p < 0.001). An additional three patients were desensitized to 1200 mg cashew protein, and three patients stopped treatment. Three patients (6%) were treated with injectable epinephrine for home reactions. Desensitized patients had decreased SPT, sIgE, basophil reactivity, and increased sIgG4, following treatment. Following cashew desensitization, all pistachio (n = 35) and four of eight walnut co-allergic patients were cross-desensitized to the respective nut. All (n = 44) patients consuming a low cashew dose for ≥6 months following desensitization passed a full-dose cashew OFC. CONCLUSIONS: Cashew OIT desensitizes most cashew-allergic patients and cross-desensitizes to pistachio. Safety is similar to OIT for other foods.

Combinatorial advantage of Ses i 1-specific IgE and basophil activation for diagnosis of sesame food allergy.

BACKGROUND: The prevalence of sesame food allergy (SFA) is increasing worldwide with the potential of anaphylactic reactions upon exposure. Utility of specific component IgE testing as an alternative to the oral food challenge (OFC), the diagnostic standard, is being investigated. METHODS: Patients (n = 42) with suspected SFA completed an open OFC to sesame. Diagnostic testing included serum levels of Ses i 1-specific IgE, skin prick test with high-protein extract, and basophil reactivity (% induced CD63 expression) for each patient. The diagnostic utility of these tests was evaluated at a 95% sensitivity, with the outcome measure being the number of OFCs required. RESULTS: Twenty-seven patients (64%) were diagnosed with SFA. Ses i 1 IgE differed significantly between allergic and tolerant patients (p = .0001). ROC curve analysis for Ses i 1 IgE yielded an AUC of 0.88 ± 0.05. Levels of Ses i 1 IgE correlated to induced CD63+ expression on basophils (p = .0001). Ses i 1 IgE was not sufficiently robust as a single step for diagnosis. Used concurrently, BAT and Ses i 1 IgE yielded correct positive classifications for 25 of 27 sesame-allergic patients with two false positives (93% PPV). Both tests were negative in 5 non-allergic patients. Patients with divergent Ses i 1 IgE and BAT results required OFC (n = 10, 24% of patients). Alternatively, sequential use of BAT, ruling in SFA followed by Ses i 1 IgE diagnosing non-allergic patients, yielded a 89% PPV, with 19% requiring OFC. CONCLUSION: Ses i 1 IgE and BAT used together can decrease the need for OFC in most SFA patients. A prospective cohort trial is necessary to validate these results.

Coronary atherosclerosis severity is closely associated with decreased GLP-1R positivity among CD16+ pro-inflammatory and patrolling monocyte subsets.

Background and aims: Glucagon Like Peptide-1 Receptor (GLP-1R) activation reduces pro-inflammatory responses of human monocytes, their accumulation in the vascular wall and foam cell formation inhibiting atherosclerogenesis. This suggests that reduction of circulating GLP-1-1R positive monocytes may have pro-atherogenic effects. It is unknown whether different CD14/CD16 monocytes subsets display GLP-1R and whether their relative proportions correlate with atherosclerosis severity. We evaluated the association between GLP-1R positivity in different CD14/CD16 monocyte subsets and coronary atherosclerosis severity. Methods: Relative amounts of classical (CD14+/CD16-), intermediate pro-inflammatory (CD14+/CD16+) and non-classical patrolling (CD14-/CD16+) subsets of total circulating monocytes and the proportions of GLP-1R positive monocytes in these subsets were determined in 13 control subjects and 10 dyslipidemic ischemic heart disease (IHD) patients with severe angiographic proven coronary atherosclerosis using flow cytometry analysis. Atherosclerosis severity was calculated by SYNTAX score. Results: In univariable analysis, severe atherosclerosis was associated with decreased proportion of classical monocytes and two fold increased CD16+ pro-inflammatory and patrolling subsets as compared with controls (p = 0.01, p = 0.02 and p = 0.01, respectively). Frequency of GLP-1R positive monocytes was decreased in both CD16+ subsets (p = 0.02 and p = 0.05, respectively) and negatively correlated with atherosclerosis severity (r = -0.65, p = 0.005 and r = -0.44, p = 0.05, respectively). Conclusions: Increased skewing of the classical monocyte population toward CD16+ pro-inflammatory and patrolling subsets accompanied by decreased in GLP-1R positivity are associated with coronary atherosclerosis severity in IHD patients with dyslipidemia. Although the effect of potential confounders cannot be ruled out, our data suggest that failure of GLP-1R-dependent anti-inflammatory/anti-atherogenic control results in innate immune system dysfunction and can promote atherosclerogenesis.

A Prospective Validation of the NUT CRACKER Diagnostic Algorithm for Walnut and Pecan Allergy with Prediction of Severity.

BACKGROUND: We previously devised an algorithm using skin prick tests (SPT), basophil activation tests (BAT), and co-allergy status to reduce the need for oral food challenges (OFCs) in 63 patients with suspected walnut/pecan allergies. OBJECTIVE: To validate prospectively the NUT CRACKER (Nut Co-Reactivity-Acquiring Knowledge for Elimination Recommendations) diagnostic algorithm in a new cohort of patients (n = 120) and to study the utility of SPT and BAT in predicting walnut-pecan allergy severity in both groups (n = 183). METHODS: Patients (n = 183) aged 8 (6-11) years, median (interquartile range), with suspected tree nut allergy were studied. SPT used ground nut extract (10 mg/mL), and BAT assessed allergen-induced basophil CD63 expression. Allergy was determined based on a recent reaction or a positive OFC, and tolerance was defined by regular consumption or a negative OFC. RESULTS: Walnut BAT was significantly higher in walnut/pecan dual compared with single walnut allergy (P = .003) and predicted the need for epinephrine during positive walnut OFCs (P = .009). Results of walnut and pecan BAT correlated with the corresponding nut eliciting dose (P = .014 and P < .001, respectively). Receiver operating curves for walnut and pecan allergy in the prospective cohort yielded area under the curves ranging from 0.87 to 0.93 for SPT and BAT. Concordant with the original study, pecan-allergic patients were all co-allergic for walnut. The algorithm decreased the need for OFCs by 78.8 % with 6 of 240 (2.5%) falsely positives and no false negatives. CONCLUSION: The algorithm was validated prospectively and awaits broader testing across other populations. The use of BAT further associates with severity in walnut/pecan allergy.

Microbial signature in IgE-mediated food allergies.

BACKGROUND: Multiple studies suggest a key role for gut microbiota in IgE-mediated food allergy (FA) development, but to date, none has studied it in the persistent state. METHODS: To characterize the gut microbiota composition and short-chain fatty acid (SCFAs) profiles associated with major food allergy groups, we recruited 233 patients with FA including milk (N = 66), sesame (N = 38), peanut (N = 71), and tree nuts (N = 58), and non-allergic controls (N = 58). DNA was isolated from fecal samples, and 16S rRNA gene sequences were analyzed. SCFAs in stool were analyzed from patients with a single allergy (N = 84) and controls (N = 31). RESULTS: The gut microbiota composition of allergic patients was significantly different compared to age-matched controls both in α-diversity and ß-diversity. Distinct microbial signatures were noted for FA to different foods. Prevotella copri (P. copri) was the most overrepresented species in non-allergic controls. SCFAs levels were significantly higher in the non-allergic compared to the FA groups, whereas P. copri significantly correlated with all three SCFAs. We used these microbial differences to distinguish between FA patients and non-allergic healthy controls with an area under the curve of 0.90, and for the classification of FA patients according to their FA types using a supervised learning algorithm. Bacteroides and P. copri were identified as taxa potentially contributing to KEGG acetate-related pathways enriched in non-allergic compared to FA. In addition, overall pathway dissimilarities were found among different FAs. CONCLUSIONS: Our results demonstrate a link between IgE-mediated FA and the composition and metabolic activity of the gut microbiota.

Clinical and Molecular Characterization of Walnut and Pecan Allergy (NUT CRACKER Study).

BACKGROUND: Diagnostic methods for distinguishing walnut-allergic patients from walnut-sensitized but walnut-tolerant individuals are limited. Furthermore, characteristics of single walnut versus dual walnut-pecan allergy are lacking. OBJECTIVE: To provide clinical and molecular characteristics of walnut- and pecan-allergic patients. METHODS: A prospective cohort study of 76 walnut-sensitized patients was performed. Walnut skin prick test and serum measurements of specific IgE to walnut and its components were performed. Patients were challenged to walnut and pecan unless they regularly consumed walnut and pecan. RESULTS: Of the 76 patients studied, 61 were diagnosed as walnut-allergic and 15 as walnut-tolerant. IgE levels greater than or equal to 0.35 kUA/L to Jug r 1 or 4 provided the best diagnostic method for identifying walnut-allergic patients (accuracy, 0.93). Of the 61 walnut-allergic patients, 49 were pecan-allergic whereas 12 were pecan-tolerant. None of the walnut-tolerant patients was allergic to pecan. Dual allergic patients had significantly lower walnut reaction dose (median, 100 mg vs 1230 mg; P < .001). IgE levels greater than or equal to 0.35 kUA/L to Jug r 4, low-molecular-weight vicilins, or high-molecular-weight vicilins best segregated dual walnut-pecan-allergic patients from single walnut-allergic patients. Inhibition studies demonstrated that walnut pretreatment completely blocked IgE binding to pecan, whereas in some patients, pecan incubation only partially blocked IgE binding to walnut. CONCLUSIONS: Walnut components are helpful in diagnosing walnut allergy and in identifying patients with pecan coallergy. Competitive ELISA indicates that pecan comprises a subset of the allergenic determinants of walnut.

Efficacy and Safety of Sesame Oral Immunotherapy-A Real-World, Single-Center Study.

BACKGROUND: The presence of sesame in Western diet is increasing, making its avoidance by sesame-allergic patients more challenging. OBJECTIVE: To report the efficacy and safety of sesame oral immunotherapy (OIT). METHODS: Sixty patients aged 4 years or older, diagnosed as sesame-allergic on the basis of a positive oral food challenge, were consecutively enrolled into OIT between November 2014 and November 2017. Fifteen patients with sesame allergy, based on a positive oral food challenge or a recent immediate reaction, and a positive skin prick test result or specific IgE, continued sesame elimination and served as observational controls. Immunologic parameters were measured in a subset (OIT, n = 16; controls, n = 11) at the start and end of the study. Fully desensitized patients continued daily consumption of 1200 mg sesame protein and challenged with 4000 mg after more than 6 months. RESULTS: Fifty-three OIT-treated patients (88.4%) were fully desensitized to sesame, compared with 0% of controls. Four additional patients (total 57 of 60 = 95%) were desensitized to more than 1000 mg protein. Reactions occurred in 4.7% of hospital doses and 1.9% of home doses. Epinephrine-treated reactions occurred in 16.7% of patients for hospital and 8.3% for home doses. Significant decreases in rSes i 1 IgE (P = .007) and basophil reactivity (P = .001) and increases in sesame and rSes i 1 IgG4 (P = .001) occurred in OIT-treated patients but not in controls. Forty-seven patients desensitized to 4000 mg were evaluated more than 6 months after reaching maintenance. Only mild reactions were reported during maintenance, and all passed the 4000-mg challenge. CONCLUSIONS: Sesame-OIT is an effective alternative to sesame avoidance in allergic patients. The potential for adverse events necessitates its performance in specialized centers.

Walnut oral immunotherapy for desensitisation of walnut and additional tree nut allergies (Nut CRACKER): a single-centre, prospective cohort study.

BACKGROUND: The safety and efficacy of oral immunotherapy for tree nut allergy has not been demonstrated to date, and its effectiveness is complicated by the high prevalence of co-allergies to several nuts. This study aimed to investigate the use of walnut oral immunotherapy in the desensitisation of walnut and additional tree nuts in patients who are co-allergic to several nuts. METHODS: In a single-centre, prospective cohort study (the Nut Co-Reactivity ACquiring Knowledge for Elimination Recommendations study) at the Institute of Allergy, Immunology, and Paediatric Pulmonology at the Yitzhak Shamir Medical Centre, we recruited patients aged 4 years or older who were allergic to walnut, with or without co-allergy to pecan, hazelnut, and cashew. The diagnosis of each food allergy was based on a positive skin prick test or specific serum IgE (≥0·35 kUA/L) to the corresponding nut together with a positive oral food challenge, unless an immediate (within 2 h of exposure) reaction in the past year had been documented. Patients with uncontrolled asthma or a medical contraindication to receive adrenaline were excluded. Patients were assigned to walnut oral immunotherapy or the control group (observation and strict dietary exclusion) on the basis of the order of presentation to the clinic. Oral immunotherapy began with a 4-day dose-escalation phase to establish the single highest tolerated dose, which was consumed daily at home for 24 days; subsequent monthly dose escalations were repeated until 4000 mg walnut protein was achieved. Patients who were desensitised to walnut continued to consume 1200 mg walnut protein daily for 6 months as maintenance. The primary outcome was walnut desensitisation (passing an oral food challenge with 4000 mg of walnut protein) at the end of the study, analysed by intention to treat. In patients who were co-allergic to pecan, hazelnut, and cashew, the proportion who achieved cross-desensitisation to these nuts in addition to walnut desensitisation was examined. FINDINGS: 73 patients with a walnut allergy were enrolled between May 15, 2016, and Jan 14, 2018. 49 (89%) of 55 patients in the oral immunotherapy group were desensitised to walnut compared with none of 18 patients in the control group (odds ratio 9·2, 95% CI 4·3-19·5; p<0·0001). Following walnut desensitisation, all patients who were co-allergic to pecan (n=46) were also desensitised to pecan. Additionally, 18 (60%) of 30 patients who were co-allergic to hazelnut or cashew, and 14 (93%) of 15 patients who were co-allergic to hazelnut alone, were either fully desensitised or responded to treatment. 47 (85%) of 55 patients had an adverse reaction (mostly grade 1 or 2) during up-dosing in the clinic; eight patients required intramuscular epinephrine in response to a dose at home. Of 45 patients who had follow-up data for the maintenance phase, all maintained walnut desensitisation and one patient required epinephrine during this period. INTERPRETATION: Walnut oral immunotherapy can induce desensitisation to walnut as well as cross-desensitisation to pecan and hazelnut in patients who have tree nut co-allergies, with a reasonable safety profile. A low daily dose of the allergen maintains desensitisation. FUNDING: None.

Phospholipase C-Gamma 2 Activity in Familial Steroid-Sensitive Nephrotic Syndrome.

BACKGROUND: Familial Steroid-sensitive Nephrotic Syndrome (SSNS) is rare, complicating the identification of candidate genes. A recent population-based approach study of SSNS identified HLA-DQA1 and Phospholipase C-Gamma 2 (PLCG2) missense coding variants as candidate loci. PLCG2 is a signaling molecule regulated by phosphorylation and is critical for Ca2+ flux in cells of the immune system. METHODS: In order to detect a candidate gene for familial SSNS, we conducted an whole-exome sequencing in a pedigree consisting of two healthy parents, two non-identical twin brothers with SSNS, and a healthy young sibling. Flow cytometric assays were conducted to investigate the effects of the identified PLCG2 rare variants on B cell receptor-mediated PLCG2 tyrosine 759 phosphorylation, as well as on Ca2+ flux. RESULTS: Two missense rare variants in the PLCG2 gene were detected in the affected twins. An increase in tyrosine phosphorylation of PLCG2 as well as more rapid Ca2+ flux were noted in response to stimulation in the affected twins compared to their parents. CONCLUSIONS: Rare variants in PLCG2 segregated with disease in familial SSNS. Functional studies suggest the combined rare variants result in a gain of function in PLCG2 activity. Taken together, these results support PLCG2 as a possible candidate locus for familial SSNS.

Food allergy to previously tolerated foods: Course and patient characteristics.

BACKGROUND: The acquisition of food allergy (FA) to previously safely consumed basic food proteins is an unusual presentation of immunoglobulin E (IgE)-mediated allergic disease. OBJECTIVE: We sought to characterize patients who developed FA to previously tolerated foods (FA-PTF), including underlying reasons for and length of elimination diet of previously tolerated foods. METHODS: Patients (n = 30) with complaints consistent with FA to foods previously consumed safely were evaluated. Clinical history was obtained, and skin prick testing and graded oral food challenges (OFC) were performed. One fatal case of FA-PTF was reported by a physician. RESULTS: Twenty-two of 30 patients (ages 1.2-50 years) were diagnosed with FA-PTF by OFC to milk (n = 17), egg (n = 2), and peanuts (n = 3). One additional patient with FA-PTF had a fatal reaction to milk. Anaphylactic reactions were reported in 12 of these 23 FA-PT patients (52%); 8 experienced multiple episodes. Atopic dermatitis was diagnosed in 52% (12/23) of patients, 8 of 12 as severe; overall, 18 of 23 (78%) of patients had marked personal atopic background. Sixteen patients (70%) initiated an elimination diet, 12 of whom did so on advice from a health care provider, before the appearance of allergic symptoms. However, in 4 patients with FA-PTF, reactivity to the food protein emerged during uninterrupted consumption. CONCLUSION: Food allergy to previously tolerated foods primarily appears after an elimination diet in atopic patients. Anaphylactic reactions are common. Health care providers should consider these risks before recommending elimination diet of tolerated foods.

Efficacy of baked milk oral immunotherapy in baked milk-reactive allergic patients.

BACKGROUND: Patients with IgE-mediated cow's milk allergy who are nonreactive to baked milk (BM) can be desensitized with BM to promote tolerance to unheated milk (UM). OBJECTIVE: We sought to test whether patients who are BM reactive can progress in BM oral immunotherapy (OIT) and become desensitized to UM as well. METHODS: Fifteen patients (>4 years) who previously failed to complete our milk OIT program were enrolled into the BM OIT protocol. A dose of BM (180 °C for 30 minutes) which was less than the eliciting dose was increased 50% monthly while under medical supervision until the primary outcome dose of 1.3 g/d BM protein was achieved. Basophil reactivity and milk protein-specific IgE binding were analyzed at the first round of BM OIT therapy (T0) and at 12 months of BM treatment. RESULTS: In terms of the primary outcome, only 3 (21%) of 14 patients tolerated the 1.3 g/d BM dose. Although some patients initially progressed in BM OIT, 8 of 11 failed because of IgE-mediated reactions. Three did not complete the program because of non-IgE-mediated factors. An increase in challenge threshold to UM was noted in patients continuing until 12 months (P = .003), including those among whom reactions precluded continuation in the program. Patients (n = 3) who successfully reached maintenance had decreased milk-specific IgE reactivity. Furthermore, the mean difference at T0 between induced HM and UM percentages of CD203c expression was significantly lower in patients who successfully completed BM OIT than in those who did not (-11% vs 4.4%, P = .0002), which is consistent with their decreased clinical reactivity to BM. CONCLUSIONS: Although use of hypoallergenic BM in OIT is a promising therapy, care must be taken before its administration in BM-reactive patients because of the risk for anaphylaxis and only limited increase in challenge threshold attained.

Dimerization of NKp46 receptor is essential for NKp46-mediated lysis: characterization of the dimerization site by epitope mapping.

NKp46 is a primary activating receptor of NK cells that is involved in lysis of target cells by NK cells. Previous studies showed that the membrane-proximal domain of NKp46 (NKp46D2) retained the binding of NKp46 to its ligands and is involved in lysis. We studied NKp46D2 by using a peptide-based epitope mapping approach and identified an NKp46D2-derived linear epitope that inhibited NKp46-mediated lysis. The epitope, designated as pep4 (aa 136-155), interacted with NKp46, and lysis by NK cells was inhibited by the presence of pep4. Through modeling and mutagenesis, we showed that pep4 could be involved in NKp46 homodimerization. R145 and D147 contribute to the function of pep4, and R145Q mutation in recombinant NKp46 reduced its binding to target cells. At the cellular level, fluorescent resonance energy transfer analysis revealed that pep4 is indeed involved in dimerization of cell membrane-associated NKp46. We suggest that the NKp46-derived pep4 site is part of the dimerization surface of NKp46 and that NKp46 dimerization contributes to NKp46-mediated lysis by NK cells.

Human NK cell recognition of target cells in the prism of natural cytotoxicity receptors and their ligands.

The matter of the pathogen- and cancer-associated ligands recognized by the Natural Cytotoxicity Receptors (NCRs) has been a subject of intense research ever since the identification of the NCRs more than 12 years ago by Alessandro and Lorenzo Moretta: NKp46 in 1997, NKp44 in 1998, and finally NKp30 in 1999. Expression patterns recognized by NCRs include pathogen-derived, pathogen-induced, and cancer-associated cellular 'self' ligands. Pathogen-exposed cells may exhibit both types of pathogen-associated ligands. Transformed cells, in contrast, exhibit only 'self' ligands which are derived from both the intracellular- and membrane-associated milieu of self molecules. These expression patterns allow for NCR-based NK cell discrimination between healthy and affected cells, in the realms of both pathogenic infection and potential tumorigenesis. The focus of this review is on the current knowledge regarding the identities of NCR ligands and the type of target cells expressing these ligands.

Upregulation of MHC class I expression following dengue virus infection: the mechanism at the promoter level.

Unlike many other viruses that downregulate MHC class I expression on infected cell membranes, flaviviruses were reported to upregulate the MHC class I expression. Dengue virus was shown to induce HLA class I expression; however, the precise transcriptional mechanism that is used by the virus remains unclear. This article assessed the findings of a recently published report describing the mechanism used by dengue virus to induce HLA-A2 expression and characterizing the transcription factors that are involved. The study showed that p50/p65 and p65/65 NF-κB dimers bind to the class I regulatory complex within the HLA-A2 promoter. This finding and its significance for the design of possible antiviral therapeutic agents are discussed in this article.

Proliferating cell nuclear antigen is a novel inhibitory ligand for the natural cytotoxicity receptor NKp44.

NK cells play an important role in the early immune response to cancer. The NKp44 activating receptor is the only natural cytotoxicity receptor that is expressed exclusively by primate NK cells, yet its cellular ligands remain largely unknown. Proliferating cell nuclear Ag (PCNA) is overexpressed in cancer cells. In this study, we show that the NKp44 receptor recognizes PCNA. Their interaction inhibits NK cell function through NKp44/ITIM. The physical interaction of NKp44 and PCNA is enabled by recruitment of target cell PCNA to the NK immunological synapse. We demonstrate that PCNA promotes cancer survival by immune evasion through inhibition of NKp44-mediated NK cell attack.

The immunological impact of genetic drift in the B10.BR congenic inbred mouse strain.

The MHC-matched, minor histocompatibility Ag (miHA)-mismatched B10.BR-->CBA strain combination has been used to elucidate the immunobiology of graft-vs-host disease (GVHD) following allogeneic bone marrow transplantation. Studies conducted in the 1980s had established that B10.BR CD8+ T cells were capable of mediating GVHD in the absence of CD4+ T cells, and that CD4+ T cells were unable to induce lethal disease. In more recent studies with this GVHD model, we detected etiological discrepancies with the previously published results, which suggested that genetic drift might have occurred within the B10.BR strain. In particular, there was increased allorecognition of CBA miHA by B10.BR CD4+ T cells, as determined by both TCR Vbeta spectratype analysis and the induction of lethal GVHD in CBA recipients. Additionally, alloreactivity was observed between the genetically drifted mice (B10.BR/Jdrif) and mice rederived from frozen embryos of the original strain (B10.BR/Jrep) using Vbeta spectratype analysis and IFN-gamma ELISPOT assays, suggesting that new miHA differences had arisen between the mice. Furthermore, T cell-depleted B10.BR/Jdrif bone marrow cells were unable to provide long-term survival following either allogeneic or syngeneic bone marrow transplantation. Gene expression analysis revealed several genes involved in hematopoiesis that were overexpressed in the lineage-negative fraction of B10.BR/Jdrif bone marrow, as compared with B10.BR/Jrep mice. Taken together, these results suggest that genetic drift in the B10.BR strain has significantly impacted the immune alloreactive response in the GVHD model by causing altered expression of miHA and diminished capacity for survival following transplantation into lethally irradiated recipients.