Prevention of recurrent respiratory tract infections: a literature review of the activity of the bacterial lysate Lantigen B.

OBJECTIVE: Lantigen B, a bacterial lysate, was developed in the 1960s and showed a prophylactic effect in patients with recurrent respiratory tract infections. The objective of this article is to review the literature to update the efficacy and safety profile of Lantigen B in preventing recurrent respiratory tract infections (RRTI). MATERIALS AND METHODS: Articles available from international data banks and producing company archives were used. Only clinical studies providing a control group were considered. The effects of Lantigen B on the number of infectious episodes or comparable parameters were analyzed. RESULTS: 22 randomized clinical trials on 4,571 patients published between 1963 and 2014, with different methodologic accuracy, consistently demonstrated that Lantigen B reduced RRTI vs. placebo (RR -0.47; 95% CI = -0.38 to -0.56). The RR always favored Lantigen B in all the other subsets analyzed in adults with RRTI (RR = -0.48; 95% CI = - 0.33 to -0.62) and children (RR = -0.490; 95% CI = - 0.36 to -0.61). Unfortunately, some studies performed in the past evaluated a small number of patients, and clinical procedures were not always performed according to the more recent good clinical practices. Despite these evident limitations of considered studies, the response frequency has remained almost unchanged since the first articles in the 1960s. CONCLUSIONS: These data confirm the efficacy of Lantigen B alone in the prophylaxis of acute respiratory infections in adults and children but also suggest that Lantigen B, used with novel therapeutic strategies, can further improve clinical outcomes.

The involvement of IgH enhancer HS1.2 in the pathogenesis of Crohn's disease: how the immune system can influence a multifactorial disease.

OBJECTIVE: To study the 3' immunoglobulin heavy-chain regulatory region (3'RR) enhancer complex, active in class switching recombination and in B-cells, in Crohn's disease. PATIENTS AND METHODS: A total of 167 patients [79 females (47.3%) and 88 males (52.7%)] affected by Crohn's disease were enrolled in the study. As a control, we included 64 healthy subjects, age and sex matched, from the same geographical area. Blood tests were performed on all subjects to determine their antibody levels and to detect the presence of any possible infections. We conducted a selective PCR, which amplified the hs1.2-A region. The nested second PCR to amplify the polymorphic core of the enhancer was performed. RESULTS: No differences between cases and controls were observed with respect to sex distribution (43.8% females among controls and 49.5% among cases), age, tTG IgA, RF, serum or secretory IgA, IgG1, IgG2 and IgG3. No correlation was found between both seric and secretory immunoglobulins levels, with except of statistically significant differences between cases and controls with respect to IgA and IgG ASCA positivity (p<0.001), serum IgG4 (p<0.001) and IgD (p=0.001). CONCLUSIONS: We have demonstrated that in Crohn's disease, the HS1,2 immunoglobulins enhancer is not implicated in the disease pathogenesis. Moreover, we have found that IgG4 levels are lower in Crohn's disease patients than in controls; these data may be related to an impairment of number and function of Tregs, further linked to the presence of tissue inflammation. Crohn's disease is a complex multifactorial disease. The pathogenesis of Crohn's disease is incompletely understood although it is clear that the disease involves multiple interacting agents.

Whole-genome sequencing as standard practice for the analysis of clonality in outbreaks of meticillin-resistant Staphylococcus aureus in a paediatric setting.

Meticillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of hospital-associated infections. This study investigated the potential use of whole-genome sequencing (WGS) for surveillance purposes by re-examining MRSA strains related to past outbreaks among hospitalized paediatric patients. WGS data ameliorated the genotypic profile previously obtained with Sanger sequencing and pulsed-field gel electrophoresis typing, and discriminated between strains that were related and unrelated to the outbreaks. This allowed strain clonality to be defined with a higher level of resolution than achieved previously. This study demonstrates the potential of WGS to trace hospital outbreaks, which may lead to WGS becoming standard practice in outbreak investigations.

Molecular diagnosis and the Italian Board for ISAC.

The Component Resolved Diagnostic (CRD) approach has been developed when highly purified or recombinant allergen molecules have become available. These molecules are the allergenic proteins toward which the specific and clinically relevant IgE immune response is directed. So, the identification of protein families and cross-reactivity patterns of importance in allergy have been possible. The Italian advisory BOARD for ISAC was born: to evaluate the advantages, disadvantages and placement in diagnosis of CRD studying its application in allergic patients; to facilitate the interpretation of molecular diagnostics for clinical allergists; to evaluate the effectiveness of CRD in improving diagnostic risk assessment and early preventive treatment of allergic diseases. In the last years, its fields of interest have been: the evaluation of the performance of CRD on multi-sensitized allergic patients with respiratory symptoms and on poly-sensitized athletes; the evolution of IgE repertoire directed to single allergenic components by evaluating allergic patients with different age at a molecular level; the relevance of results obtained using allergen microarray technique for describing the IgE repertoire in allergic patients by reviewing the main articles focused on CRD published in the last 2 years; the need for an educational program focused on this new diagnostic tool also through the creation of an exhaustive and interactive explanation of the laboratory report molecular allergy; the investigation of the performance and potential additional diagnostic values of the ISAC microarray in a real-life clinical setting, taking into account also the economic values.

The additional values of microarray allergen assay in the management of polysensitized patients with respiratory allergy.

BACKGROUND: The IgE response is directed against specific components from an allergenic source. The traditional diagnostic methods use whole extracts, containing allergenic, nonallergenic and cross-reactive molecules. This may pose diagnostic challenges in polysensitized patients. Microarray techniques detect specific IgE against multiple molecules, but their value in term of additional information and economic saving has not been yet defined. OBJECTIVE: We assessed the additional diagnostic information provided by an allergen microarray in a large population of polysensitized subjects. METHODS: In this multicentre study, allergists were required to carefully record diagnosis and treatment of consecutive patients referred for asthma/rhinitis, using the standard methodology (history, skin prick test, IgE assay). Then, a microarray allergen assay was carried out. Clinicians were required to review their diagnosis/treatment according to microarray results. RESULTS: 318 allergic patients (30% reporting also nonrespiratory symptoms) and 91 controls were enrolled. The clinicians reported at least one additional information from the microarray in about 60% of patients, this resulting in therapeutic adjustments. In 66% of patients IgE to pan-allergens were detectable, being this clinically relevant in 38% of patients with polysensitization to pollens. CONCLUSION: Microarray IgE assay represents an advancement in allergy diagnosis, as a third-level approach in polysensitized subjects, when the traditional diagnosis may be problematic.

Occupational asthma associated to the exposure to limonium tataricum flowers.

Limonium tataricum (Lt) is a plant belonging to the family of Plumbaginaceae. The role of this family and in particular, that of dried flowers (but not of the pollen) in occupational allergy has already been described. We have observed a farmer with asthma occurring in the presence of fresh flowers. Standard methacoline test demonstrated that the patient was a true asthmatic. The allergenicity of Lt pollen was thus investigated Skin prick tests (SPT) were carried out using both standard allergens and the Lt extract and the patient's mucosal reactivity was evaluated by nasal provocation test with the pollen extract. In vitro studies were also performed on the patient's serum by evaluating routine specific anti-allergen IgE on raw extracts and on Microarray Allergen Chip (ISAC). Finally, the raw extract of the fresh Lt pollen was also used in ELISA inhibition test, immunoblotting and Basophil Activation Test (BAT). The specific sensitization was demonstrated by Skin Prick test and nasal provocation test. The sensitization was also confirmed by specific IgE and by in vitro activation of basophils in the presence of the pollen. By using RAST inhibition test, the presence of cross-reactivity with other pollens was ruled out. According to our results, Lt extracts contain an allergenic activity not only as dried flowers, but also as fresh pollen. For its role in occupational asthma, this allergen should be included in any allergy screening at least in farmers or in the flower industry employers.

Comparison of antibody-conjugated magnetic immunoassay and liquid chromatography-tandem mass spectrometry for the measurement of cyclosporine and tacrolimus in whole blood.

The aim of this work is to compare the results of a commercially available liquid chromatography tandem mass spectrometry (LC-MS/MS) method in a clinical pathology laboratory for routine Therapeutic Drug Monitoring (TDM) of cyclosporine (CsA) and tacrolimus (Tacr) in pediatric patients with those obtained with the current antibody-conjugated magnetic immunoassay (ACMIA). Whole blood levels of CsA (n= 135) and Tacr (n=100) were sequentially analyzed by using ACMIA and LC-MS/MS on pediatric transplanted patients. The differences were analyzed by using the Passing Bablok regression analysis and the Bland and Altman test. The LC-MS/MS method showed excellent reproducibility and lower limits of quantification compared to the ACMIA. A linear relationship between ACMIA and LC-MS/MS was obtained for both CsA Tacr. No significant inter-method biases were observed. The analytical performances of the LC-MS/MS method make it suitable for the accurate measurement of CsA and Tacr in pediatric transplanted patients. However ACMIA results are also accurate and reliable. For this reason the choice of the method to be used in a routine clinical pathology laboratory can be made on the bases of non-analytical considerations such as costs, organization, availability of skilled personnel.

Laboratory diagnosis of Streptococcus pneumoniae infections: past and future.

Streptococcus pneumoniae is one of the most important causative agent of pneumonia, meningitis, bacteremia, sinusitis and otitis media. The gold standard diagnostic method is still culture even if bacteriological diagnosis is making progress in molecular biology and in proteomics areas.

Microarray evaluation of specific IgE to allergen components in elite athletes.

BACKGROUND: Allergic sensitization and diseases have been reported to have a very high and increasing prevalence in elite athletes. Over 80% of allergic athletes are poly-sensitized. OBJECTIVE: This study aims at evaluating the potential diagnostic added value of a microarray technology (ImmunoCAP ISAC, Phadia AB [at present Thermo Fisher Scientific] Uppsala, Sweden which detects IgE antibodies to specific or cross-reacting allergen components. METHODS: Seventy-two poly-sensitized athletes according to skin prick test (SPT) with different allergic phenotypes (asthma n = 19; rhino-conjunctivitis n = 20; food allergy and/or oral allergy syndrome n = 13; no clinical symptoms n = 20) and two different control populations (20 poly-sensitized sedentary subjects with respiratory allergy and 20 healthy athletes with negative SPT) were studied for detecting specific IgE (sIgE) both to allergen extracts (ImmunoCAPsIgE) and to allergen components (ImmunoCAP ISAC). RESULTS: ImmunoCAP ISAC detected the presence of sIgE in 90% of poly-sensitized athletes--in 96% with symptoms and in 75% without symptoms--and in 100% of allergic controls. The pattern of positivity towards the 103 components tested differed from subject to subject, even in those with the same sensitization to allergen extract SPT or sIgE. Based on the ISAC results, poly-sensitized athletes were classified into the following prototypical patterns, differently represented in the clinical phenotypes studied (P = 0.03): (1) One single predominant specific allergen positivity; (2) sIgE to two or more non-cross-reacting allergens; (3) sIgE to cross-reacting allergens; and (4) sIgE to components potentially responsible for severe allergic reactions. CONCLUSIONS: The ImmunoCAP ISAC represents a useful additional tool for diagnosis and management of poly-sensitized athletes.

The role of basophil activation test in special populations with mastocytosis and reactions to hymenoptera sting.

BACKGROUND: Systemic mastocytosis (SM) may be associated with hymenoptera allergy. In such cases, immunotherapy is a life-saving treatment, but a circumstantiated diagnosis is needed for its prescription. Patients with SM and previous reactions to stings, but with negative tests represent a diagnostic dilemma. The basophil activation test (BAT) may be helpful in refining the diagnosis. OBJECTIVE: We assessed the usefulness of BAT in subpopulations of mastocytosis patients, including those with negative tests for insect allergy. METHODS: Within a population of patients with mastocytosis and previous stings, we studied by BAT and augmented intradermal test (IDT) (10 µg/ml) two groups: (1) with reactions to stings and negative tests; (2) without reactions and negative tests. Basophil activation test was performed with different venoms, assessing at flow cytometry basophils' activation. RESULTS: Sixty-three patients had mastocytosis and 52 had reactions to previous hymenoptera stings. Of them, seven proved negative to diagnostic tests. In six of seven of those patients, BAT was negative with all venoms, and in one, basophils resulted activated also with the negative control. In six patients without previous reactions and negative tests, BAT was totally negative in five of six patients and weakly positive to Hornet in one. Finally, the IDT at 10 µg/ml venom produced nonspecific positive results in most cases. CONCLUSION: In patients with mastocytosis, the negative results of standard tests are reliable, because BAT and IDT at higher concentration do not add useful information.

A validated HPLC method for the monitoring of thiopurine metabolites in whole blood in paediatric patients with inflammatory bowel disease.

Therapeutic drug monitoring (TDM) of major metabolites of thiopurine drugs is a widely used tool for assessing treatment efficacy and toxicity in patients with inflammatory bowel disease (IBD). We report the laboratory and clinical validation of a simple and reliable high performance liquid chromatography (HPLC) method for the measurement of 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP) on paediatric patients with IBD. The aim of this paper is to develop and validate a method for the measurement of 6-TGN and 6-MMP applicable to routine practice and to evaluate the usefulness of the TDM of thiopurine drugs in children with IBD attending our Gastroenterology Unit. The HPLC method was validated following international guidelines starting from red blood cells (RBC) and whole blood (WB). A comparison between RBC and WB was assessed. The usefulness of TDM was then evaluated using the new method from WB in 47 paediatric patients with IBD treated with thiopurine drugs. WB and RBC resulted in interchangeable matrices. The majority of patients had the metabolite levels inside the therapeutic ranges. A moderate correlation was found between 6-MMP concentration and the dose of thiopurines. A higher percentage of non responders was found among patients with lower levels of 6-TGN. Toxicity was found in eight patients and was evaluated in respect to the metabolite concentration. The described HPLC method is applicable to routine practice and it is suitable for its use in multicentric studies. Our results of TDM on paediatric IBD patients can contribute to clarify its role in their therapeutic management.

Serum insulin-like growth factor-I (IGF-I) reference ranges for chemiluminescence assay in childhood and adolescence. Data from a population of in- and out-patients.

BACKGROUND: Insulin-like growth factor I (IGF-I) measurement is widely used for the diagnosis of disorders of GH secretion and sensitivity, and for monitoring of both GH and IGF-I replacement therapies. However, the lack of appropriate reference values obtained from large and representative samples undermines its practical utility. OBJECTIVE: To establish IGF-I reference values for a commonly used enzyme-labeled chemiluminescent immunometric assay in a large population of children aged 0 to 18 years. DESIGN: Cross-sectional analysis of serum IGF-I levels from samples collected in the two major Italian Children's Hospitals. SUBJECTS AND METHODS: IGF-I was measured using a solid-phase, enzyme-labeled chemiluminescent immunometric assay in 24403 children (50.6% girls) aged 0 to 18 years. Quantile regression coupled to multivariable fractional polynomials was used to produce age- and sex-specific reference values. MAIN OUTCOME MEASURE: Age- and sex-specific IGF-I reference values. RESULTS AND CONCLUSION: Reference values for immunometric assay of IGF-I were produced in a large sample of children and adolescents. Prediction equations were provided to automatize their calculations.

The relationship between mucosal immunoresponse and clinical outcome in patients with recurrent upper respiratory tract infections treated with a mechanical bacterial lysate.

This open prospective study aims to evaluate whether a therapy with a polyvalent mechanical bacterial lysate (PMBL) could be associated to the enhancement of the locoregional immunoresponse in patients with recurrent upper respiratory tract infections. Forty patients (23 females and 17 males) were enrolled, 33 of whom concluded the study. The duration of the study was six months and each patient was visited five times. Twenty-six patients had an objective improvement in clinical and medical locoregional conditions, while in seven patients the treatment did not result in an objective amelioration. Twenty-five out of 27 patients with clinical response were characterized by an increase of specific antibodies against PMBL antigens in salivary fluids. Only two patients, with a non-significant clinical result, had a slight increase in the concentration of salivary specific IgA. The association between PMBLspecific immunoglobulin titers and clinical results was significant for IgG and IgA, but not significant for IgM. Th1 switch was detected only in patients with clinical amelioration, while the Th0 phenotype was observed in three responder and four non-responder patients. Weak Th2 polarization was also observed in one clinical responsive patient. The capacity of effectively opsonizing living bacteria was detected in samples derived from responder patients. These results suggest that PMBL treatment was able to trigger an efficient and well-targeted immune-response resulting in positive clinical outcome of the patients treated.

Burden of rotavirus infections in Liguria, Northern Italy: hospitalisations and potential savings by vaccination.

We evaluated the rates of gastroenteritis admissions to the emergency department and of rotavirus-related hospitalisations in children ≤5 years of age in 2006 at an Italian paediatric hospital. We calculated the number of rotavirus cases avoidable through the universal vaccination of children. Epidemiological data were extracted from the Data Elaboration Centre. To calculate the hospitalisation rate due to rotavirus, the virus was sought in the faeces of children hospitalised for acute gastroenteritis by means of rapid immunochromatographic assay. Emergency department admissions due to gastroenteritis numbered 2,396 (11.58% of the total admissions). Of these, 276 children (11.52%) were examined and then sent home, 1,286 (53.67%) were kept in short observation and 776 (32.38%) were hospitalised. In 27.83% of hospitalised cases, the rotavirus test proved positive. The rotavirus hospitalisation rate was 55 per 10,000 children ≤5 years of age in Genoa in 2006. In 85.6% of hospitalised patients with community-acquired rotavirus infection, the disease was severe. The number of avoidable cases confirmed that the vaccination of children ≤1 year of age could reduce the burden of rotavirus infection, especially with regard to hospitalisation (45 per 10,000 children ≤5 years of age) and admissions to short observation (85 per 10,000), generating benefits for the Italian healthcare system.

Sensitization profiles in polysensitized patients from a restricted geographical area: further lessons from multiplexed component resolved diagnosis.

BACKGROUND: The micro-array techniques for the detection of specific IgE has improved the diagnostic procedures for allergic diseases. This method also allows to define sensitisation profiles from an epidemiological point of view. We studied the sensitisation pattern in a population of polysensitized patients with respiratory allergy, living in a restricted geographical area in the north-west Italy. METHODS: Consecutive patients with asthma/rhinitis, living in the province of Cuneo, and having at least two positive skin prick test for non related aeroallergens were studied by a microarray (Phadia, Milan Italy) which allowed to detect specific IgE against 103 different allergen components. RESULTS: The 70 patients included had specific IgE towards a mean of 4.3 allergens/patient (range 2-12 allergens). Concerning pollens, 63 (90%) had specific IgE to at least one genuine grass pollen allergen, 32 (45.7%) had Ole e 1 specific IgE antibodies, although olive tree is not present in the area. A relevant percentage of sensitisation to mite was found (47,1%). True co-sensitisation to grass-pollen allergens/Bet v 1/Ole e 1 was observed in 15 individuals (21.4%). Prup 1, resulted to be a sensitising allergen in 23 patients (32.85%), 4 of whom were co-sensitised to Prup 3 and/or Art v 3. CONCLUSION: A detailed knowledge of the sensitisation pattern may have relevant implications for the prescription of specific immunotherapy. Moreover, sensitisation to PR-10 (or profilin), frequently associated to oral allergy syndrome, in some cases could hide the sensitisation to LTPs which are clinically more relevant.

Neo-adjuvant chemo/immunotherapy in the treatment of stage III (N2) non-small cell lung cancer: a phase I/II pilot study.

In a previous randomized study, we showed that adjuvant immunotherapy with tumor-infiltrating lymphocytes and recombinant interleukin-2 (rIL-2) significantly improved survival in resected N2-non small cell lung cancer (NSCLC) patients. The present study assesses feasibility, safety and potential efficacy of combined neo-adjuvant chemotherapy and immunotherapy with peripheral blood mononuclear cells (PBMC) and rIL-2 in resectable N2-NSCLC patients. Eighty-two consecutive N2-NSCLC patients underwent neo-adjuvant chemotherapy with cisplatin and gemcitabine. Out of the 82 patients, 23 were also subjected to leukapheresis prior to neo-adjuvant chemotherapy while the remaining 59 did not. Collected PBMC were analyzed for viability and phenotype and then stored frozen in liquid nitrogen. Thawed PBMC were infused intravenously, 5 days before surgery. After the infusion, rIL-2 was administered subcutaneously until surgery. Only patients with a partial or complete response to neoadjuvant chemotherapy underwent surgery: 13 patients in the experimental immunotherapy group (A) and 32 in the reference group (B). The two groups were homogeneous for all major prognostic factors. Median leukapheresis yield was 10 billion PBMC, (range 3-24 billions). Two to six billion PBMC were infused. The phenotypic analysis showed that similar proportions of CD4 and CD8 cells were present in leukapheresis products, and thawed PBMC, as well as in T lymphocytes isolated from the removed tumours. No severe adverse effects were observed following immunotherapy. No significant differences in overall survival (OS) and event-free survival (EFS) were seen between the two groups. However, the 5-year OS in group A was almost twice as much compared to group B (59 percent vs 32 percent). After adjustment for major prognostic factors, a statistically significant 66 percent reduction in the hazard of death was seen in patients receiving immunotherapy. The OS benefit was more evident in patients with adenocarcinoma than in those with squamous cell carcinoma. This study supports the favorable toxicity profile and potential efficacy of combining neo-adjuvant chemotherapy and immunotherapy with PBMC and rIL-2 in the treatment of N2-NSCLC patients.

Morphological diagnosis by bone marrow aspirate of toxoplasmosis infection in an HIV-positive patient.

An HIV-positive woman receiving antiretroviral therapy developed an opportunistic toxoplasma infection, detected by morphological examination of bone marrow aspirate in the absence of serological positivity. The intracellular presence of Toxoplasma gondii was confirmed by indirect immunofluorescence microscopy, using a polyclonal antitoxoplasma antiserum on marrow smears. This case report confirms the utility of morphological bone marrow examination for the diagnosis of parasitic infections in patients with impaired host defenses.

New approach for rapid detection of known hemoglobin variants using LC-MS/MS combined with a peptide database.

The identification of hemoglobin (Hb) variants is usually performed by means of different analytical steps and methodologies. Phenotypic methods, such as gel electrophoresis and high performance liquid chromatography, are used to detect the different electrophoretic or chromatographic behaviors of hemoglobin variants in comparison to HbA0 used as a control. These data often need to be combined with mass spectrometry analyses of intact globins and their tryptic peptide mixtures. As an alternative to a 'step-by-step' procedure, we have developed a 'single step' approach for the identification of Hb variants present in biological samples. This is based on the microHPLC-ESI-MS/MS analysis of the peptide mixture generated by a tryptic digestion of diluted Hb samples and an in-house new database containing solely the variant tryptic peptide of known human Hb variants. The experimental results (full MS and MS/MS spectra) are correlated with theoretical mass spectra generated from our in-house-built variant peptide database (Hbp) using the SEQUEST algorithm. Simple preparation of samples and an automated identification of the variant peptide are the main characteristics of this approach, making it an attractive method for the detection of Hb variants at the routine clinical level. We have analyzed 16 different samples, each containing a different known variant of hemoglobin.

Bacterial lysate in the prevention of acute exacerbation of COPD and in respiratory recurrent infections.

Respiratory tract infections (RTIs) represent a serious problem because they are one of the most common cause of human death by infection. The search for the treatment of those diseases has therefore a great importance. In this study we provide an overview of the currently available treatments for RTIs with particular attention to chronic obstructive pulmonary diseases exacerbations and recurrent respiratory infections therapy and a description of bacterial lysate action, in particular making reference to the medical literature dealing with its clinical efficacy. Those studies are based on a very large number of clinical trials aimed to evaluate the effects of this drug in maintaining the immune system in a state of alert, and in increasing the defences against microbial infections. From this analysis it comes out that bacterial lysates have a protective effect, which induce a significant reduction of the symptoms related to respiratory infections. Those results could be very interesting also from an economic point of view, because they envisage a reduction in the number of acute exacerbations and a shorter duration of hospitalization. The use of bacterial lysate could therefore represent an important means to achieve an extension of life duration in patients affected by respiratory diseases.

Surface receptors and functional interactions of human natural killer cells: from bench to the clinic.

The past 10years have witnessed dramatic progress in our understanding of how natural killer (NK) cells function and their role in innate immunity. Thanks to an array of inhibitory receptors specific for different HLA class I molecules, human NK cells can sense the decrease or loss of even single alleles at the cell surface. This represents a typical condition of a potential danger, i.e. the presence of tumor or virally infected cells. NK cell triggering and lysis of these cells is mediated by several activating receptors and coreceptors that have recently been identified and cloned. While normal cells are usually resistant to NK-mediated attack, a remarkable exception is represented by dendritic cells (DCs). In their immature form they are susceptible to NK-mediated lysis because of the expression of low levels of surface HLA class I molecules. The process of DC maturation (mDCs) is characterized by the surface expression of high levels of HLA class I molecules. Accordingly, mDCs become resistant to NK cells. A recent major breakthrough highlighted the role played by donor NK cells in allogenic bone marrow transplantation to cure acute myeloid leukemias. 'Alloreactive' NK cells derived from donor hematopoietic precursors not only prevented leukemic relapses, but also prevented graft rejection and graft-versus-host disease.