MBL Genotype Research Articles

The MBL2 genotype relates to COVID-19 severity and may help to select the optimal therapy.

Sars-CoV-2 acute infection is clinically heterogeneous, ranging from asymptomatic cases to patients with a severe, systemic clinical course. Among the involved factors age and preexisting morbidities play a major role; genetic host susceptibility contributes to modulating the clinical expression and outcome of the disease. Mannose-binding lectin is an acute-phase protein that activates the lectin-complement pathway, promotes opsonophagocytosis and modulates inflammation, and is involved in several bacterial and viral infections in humans. Understanding its role in Sars-CoV-2 infection could help select a better therapy. We studied MBL2 haplotypes in 419 patients with acute COVID-19 in comparison to the general population and related the haplotypes to clinical and laboratory markers of severity. We recorded an enhanced frequency of MBL2 nullalleles in patients with severe acute COVID-19. The homozygous null genotypes were significantly more frequent in patients with advanced WHO score 4-7 (OR of about 4) and related to more severe inflammation, neutrophilia, and lymphopenia. Subjects with a defective MBL2 genotype (i.e.,0/0) are predisposed to a more severe acute Sars-CoV-2 infection; they may benefit from early replacement therapy with recombinant MBL. Furthermore, a subset of subjects with the A/A MBL genotype develop a relevant increase of serum MBL during the early phases of the disease and develop a more severe pulmonary disease; in these patients, the targeting of the complement may help. Therefore, COVID-19 patients should be tested at hospitalization with serum MBL analysis and MBL2 genotype, to define the optimal therapy.

Prevalence of Imipenemase and Verona Integron-Encoded Metalloβ-Lactamase in Imipenem-Resistant Pseudomonas aeruginosa

Objective: To determine the prevalence of metallo-β-lactamase (MBL) including imipenemase (IMP) and Verona integronencoded metallo-β-lactamase (VIM) in imipenem-resistant Pseudomonas aeruginosa (IRPA) isolates and investigate the in vitro activities of 9 antimicrobial agents against MBL-positive isolates. Material and Methods: Seventy-eight IRPA isolates were obtained from Songklanagarind Hospital. MBL production was detected by the combined-disk test, and the blaIMP and blaVIM genes were determined via Polymerase Chain Reaction (PCR). The in vitro activities of amikacin, gentamicin, aztreonam, ceftazidime, meropenem, ciprofloxacin, colistin, piperacillin/ tazobactam, and ticarcillin/clavulanate were determined using the E-test method. Results: Of the 78 IRPA isolates, 20 (25.6%, 95% CI 17.2-36.4%) were MBL phenotype-positive, and 30 (38.5%, 95% CI 28.5-49.6%) were MBL genotype-positive (29 Imipenemase (IMP)-type and 1 Verona integron-encoded metallo-βlactamase (VIM)-type). Ninety percent of the MBL genotype-positive isolates were MDR. Most MBL genotype- positive isolates were susceptible to colistin (susceptibility rate of 96.7% and MIC50 value of 1.5 µg/mL). Conclusion: Our results showed a high prevalence of MBL-positive isolates (38.5%) in IRPAs, and the IMP-type isolates were dominant among the metallo-β-lactamase-producing imipenem-resistant P. aeruginosa tested. Most MBL-positive isolates were susceptible to colistin and had low MIC50 values.

Mannose-binding lectin and risk of infections in type 2 diabetes: A Danish cohort study.

In individuals at increased risk of infections, e.g., patients with type 2 diabetes, low MBL may have detrimental effects. We used the Mendelian randomization principle to examine whether genetically low MBL is a risk factor for developing infections in patients with type 2 diabetes. Serum MBL (n = 7305) and MBL genotype (n = 3043) were determined in a nationwide cohort of patients with new type 2 diabetes and up to 8 years follow-up for hospital-treated infections and community-based antimicrobial prescriptions. The associations were examined in spline and Cox regression analyses. 1140 patients (16%) were hospitalized with an infection and 5077 patients (70%) redeemed an antimicrobial prescription. For low (≤100 μg/L) versus intermediate (101-1000 μg/L) serum MBL concentration, the adjusted hazard ratios (aHRs) were 1.13(95% confidence interval, 0.96-1.33) for any hospital-treated infections and 1.19(1.01-1.41) for bacterial infections. Low MBL expression genotype was not associated with risk of any hospital-treated infections except for diarrheal diseases (aHR 2.23[1.04-4.80]). Low MBL expression genotype, but not low serum MBL, was associated with increased risk for antimicrobial prescriptions (aHR 1.18[1.04-2.34] and antibacterial prescriptions 1.20[1.05-1.36]). Low MBL is a weak causal risk factor for developing infections in patients with type 2 diabetes.

Natural and Artificial Selection for Parasitoid Resistance in Drosophila melanogaster Leave Different Genetic Signatures.

Adaptation of complex traits depends on standing genetic variation at multiple loci. The allelic variants that have positive fitness effects, however, can differ depending on the genetic background and the selective pressure. Previously, we interrogated the Drosophila melanogaster genome at the population level for polymorphic positions and identified 215 single nucleotide polymorphisms (SNPs) that had significantly changed in frequency after experimental evolution for increased parasitoid resistance. In the current study, we follow up on 11 of these SNPs as putative targets of the experimental selection process (Jalvingh et al., 2014). We study the patterns of genetic variation for these SNPs in several European field populations. Furthermore, we associate the genetic variation of these SNPs to variation in resistance against the parasitoid Asobara tabida, by determining the individual phenotype and SNP genotype for 144 individuals from four Selection lines and four non-selected Control lines and for 400 individuals from 12 Field lines that differ in parasitoid resistance. For the Selection lines we additionally monitored the changes in allele frequencies throughout the five generations of experimental selection. For three genes, mbl (Zn-finger protein), mthl4 (G-protein coupled receptor) and CG17287 (protein-cysteine S-palmitoyltransferase) individual SNP genotypes were significantly associated with resistance level in the Selection and Control lines. Additionally, the minor allele in mbl and mthl4 were consistently and gradually favored throughout the five generations of experimental evolution. However, none of these alleles did appear to be associated to high resistance in the Field lines. We suggest that, within field populations, selection for parasitoid resistance is a gradual process that involves co-adapted gene complexes. Fast artificial selection, however, enforces the sudden cumulating of particular alleles that confer high resistance (genetic sweep). We discuss our findings in the context of local adaptation.

Development of functional mannose binding lectin is delayed in extremely low birth weight infants

Abstract Background Mannose binding lectin (MBL) is a liver derived plasma pattern recognition molecule that plays an important role in innate immune defence. Genetically driven deficiencies in MBL level and function are associated with increased frequency and severity of infection, and increased prevalence of autoimmune and chronic inflammatory diseases. Extremely low birth weight infants (ELBWI) are at increased risk of acquiring infection and innate immunity is particularly important in this group. We assessed functional MBL level and capacity to activate the complement cascade in ELBWI. Methods ELBW infants (< 1500 g, n=141) were recruited from the Mater Mothers’ Hospital (informed parental consent, ethics #492M). Whole blood was collected into EDTA coated tubes at birth (cord blood), and at D7 and D28 postpartum (heel prick). Functional MBL level and C4 deposition capacity were determined by ELISAs. MBL genotype was determined by PCR. MBL oligomerisation was determined by western blot. Full birth weight infants (n=190) and healthy adult blood donors (n=236) were used as comparators (unpaired t-test P<0.05). Results Compared to both full term neonates and adults, new born ELBW infants had significantly reduced MBL level (both P<0.001) and C4 deposition capacity (both P<0.001). Mannan binding and C4 deposition capacity of MBL in ELBW neonates increased over the first 28 Days, reaching comparative function to full term neonates by D7. Increased mannan binding and C4 deposition was associated with increased oligomerisation of MBL. Conclusions Development of functional MBL was delayed in ELBW infants. MBL oligomerisation was associated with increased capacity to activate the complement cascade.

Cardiovascular risk and mannose binding lectin in patients with rheumatoid arthritis from southern Brazil

BackgroundMannose binding lectin (MBL) appears to be involved in susceptibility to rheumatoid arthritis (RA), in the inflammatory process and in the genesis of atherosclerotic disease. ObjectiveTo study the association of MBL serum levels and its genotypic variation with carotid arteries intimal thickness (IMT) in RA patients from Southern Brazil. MethodsMBL serum levels, MBL2 genotyping and IMT were investigated in 90 RA patients along with their demographic, clinical and laboratory profile. MBL levels and MBL2 genotyping were evaluated in 90 healthy controls. ResultsA significant lower MBL serum concentration was observed in patients with RA in relation to controls (528 ng/mL vs 937.5 ng/mL, p = 0.05, respectively). The median IMT in RA patients was 0.59 mm (0.51 to 0.85 mm). There was no correlation between levels of MBL with disease activity, erythrocyte sedimentation rate, autoantibodies presence or IMT (p = NS). A weak and negative correlation was found between MBL and CRP levels (Rho = −0.24; p = 0.02;). The MBL2 variant at codon 54 (variant B) and HYPA haplotype were the most frequently observed in the RA sample (67.5% and 31.7%). MBL2 wild type (A/A) were associated with lower IMT when compared with heterozygotes (A/O; p = 0.04) and low producers (O/O; p = 0.05). In addition, high producers genotypes had lower levels of CRP when compared with medium (p = 0.04) or with low producers (p = 0.05). ConclusionRA patients had lower MBL levels than controls. MBL were negatively associated with CRP serum levels; low MBL genotypes producers increased thickness of the IMT than high producers.

Mannose-binding lectin and mannose-binding protein-associated serine protease 2 levels and infection in very-low-birth-weight infants.

The aim of this study was to explore the role of the lectin pathway in neonatal sepsis through the study of MBL and MASP2 levels and their relationship with infection in a cohort of very-low-birth-weight infants (VLBWI). MBL and MASP2 were measured in plasma samples of n = 89 VLBWI using ELISA and correlated with clinical parameters. MBL plasma levels were aligned with genotyping data of mbl2 exon 1 polymorphisms, rs1800450, rs1800451, and rs5030737. MBL levels were clearly determined by MBL genotype, i.e., AA individuals had tenfold higher MBL levels than AO individuals. MBL and MASP2 levels did not correlate with gestational age, apart from MASP2 levels on day 7. During the first 21 days of life, we noted a gradual increase in both MBL and MASP2 levels. On day 7 of life, MASP2 levels in infants developing late-onset sepsis measured before the onset of symptoms were found to be lower, as compared to non-LOS infants. In our cohort of VLBWI, MBL levels were genetically determined, but not associated with gestational age or sepsis in the first 21 days of life. Lower MASP2 levels on day 7 may indicate increased risk for late-onset infection.

Persistent changes in circulating white blood cell populations after splenectomy.

The effect of splenectomy on the incidence of infections and thromboembolisms has been investigated thoroughly. Nevertheless, the long-term effects of splenectomy on immunological profile and circulating blood counts have not been described before. To study such long-term effects, we analysed several parameters in splenectomised trauma patients and compared the results of this group ("otherwise healthy patients") to patients with a specific underlying disease. We measured platelet count, leukocytes and differential, lymphocyte subsets, serum levels of immunoglobulins, and complement pathways in 113 patients. Indications to perform a splenectomy were trauma (n=42), Hodgkin lymphoma (n=24), hereditary spherocytosis (n=21), and immune thrombocytopenia (n=26). In trauma patients lymphocytes and lymphocytes subsets were particularly elevated compared to normal population values. Splenectomised patients with Hodgkin lymphoma had significant lower numbers of T lymphocytes than trauma patients. Significant increases in platelets, leukocytes, and monocytes were observed in patients with hereditary spherocytosis. Occurrence of MBL genotype was different in ITP patients than in other splenectomised groups and the normal population. In splenectomised patients (>4years), platelet counts and lymphocyte subsets are increased which persist over time. As a result, these blood counts in splenectomised patients differ from reference values in the normal population.

Isolation of Potential Phages against Multidrug-Resistant Bacterial Isolates: Promising Agents in the Rivers of Kathmandu, Nepal.

Bacteriophages are being the subject of interest for alternative antimicrobial therapy for infectious diseases in recent years. Therapeutic effectiveness regarding phage therapy is a matter of concern since it is the most promising biological treatment of this era. Hence, the present study was aimed to isolate the potential bacteriophages present in river water samples and to analyze their host range among clinical strains of bacteria. Ten different locations of Kathmandu valley were selected for the collection of river water for the detection of probable phages. Bacteriophages were isolated from water samples using the double agar overlay method. Isolated phages were purified by diluting in the SM-buffer and filtering through 0.22 μm filter. Purified lysate was further processed for analyzing its host range by using spot method. Their host range was characterized against 20 bacterial strains, including multidrug-resistant. Total 67 different phages were isolated against 8 different host organisms. Out of them, forty-seven phages were selected for analyzing its host range. Among them, Serratia phages (ΦSER) had the broad host range infecting 17 different bacterial strains including multidrug-resistant harboring ESBL and MBL genotypes. However, Klebsiella phages (ΦKP) had narrow host range in comparison to other phages. Isolated phages had the potential effect against clinical strains of bacteria along with their broader host spectrum. Most importantly, promising effect against MDR pathogens in this study has raised the probable chances of the utility of these phages for biological control of bacterial infection including MBL and ESBL strains.

Mannose binding lectin 2 promotor-221 X/Y gene polymorphism in Egyptian systemic lupus erythematosus patients

Aim of the workThe present study was undertaken to determine whether mannose binding lectin-2 (MBL2) promotor-221X/Y gene polymorphism had a possible association with systemic lupus erythematosus (SLE) in Mansoura city. Patients and methodsWe analyzed functional polymorphisms in the promoter of MBL2 gene in 106 Egyptian SLE patients and 99 healthy controls by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). SLE disease activity was evaluated using SLE Disease Activity Index (SLEDAI) and organ damage was evaluated using SLE International Collaborating Clinic Damage Index (SLICC/DI). ResultsThe patients were 95 females and 11 males with a mean age of 34.4±10.2years and disease duration of 4±3.03years. Genotype frequencies of MBL2 were significantly different between patients and controls. The YY genotype was significantly associated with SLE in 77 (72.6%) patients compared to the control in 59 (59.6%) (p=0.048). The XY genotype was in 29 (27.4%) patients and in 40 (40.4%) control. An association was found between the XY genotype and alopecia (p=0.048), central nervous system involvement (p=0.03), vasculitis (p=0.004) and anti-phospholipid syndrome (p=0.001) while the YY genotype was associated with discoid rash, low serum complement level (C3; p=0.014 and C4; p=0.008) and with the presence of anticardiolipin antibodies (p=0.032). MBL genotype did not show any correlation with SLEDAI or SLICC/DI. ConclusionOur results indicate that MBL2 promotor-221X/Y polymorphism is a possible key-player for SLE development as well as the occurrence of some clinical and laboratory features. Further longitudinal studies including other single nucleoproteins are needed to clarify the role of MBL2.

Profile and multidrug resistance determinants of Chryseobacterium indologenes from seawater and marine fauna

The aim of this study was to investigate the prevalence and genetic basis of multidrug resistance in Chryseobacterium indologenes from seawater and marine invertebrates used for human consumption, in Kaštela Bay, Adriatic Sea, Croatia. Out of 16 samples of seawater, Mediterranean mussel (Mytilus galloprovincialis Lam.), Rayed Mediterranean limpets (Patella caerulea L.) and Purple sea urchins (Paracentrotus lividus Lam.) collected, 15 were positive for C. indologenes. In total, 41 isolates were randomly selected and tested for antibiotic susceptibility by disc-diffusion and broth microdilution methods. PCR was used to detect alleles encoding extended-spectrum (ESBLs) and metallo-β-lactamases (MBLs). The clonality of β-lactamase-producing strains was evaluated by random amplified polymorphic DNA (RAPD) analysis. All C. indologenes isolates showed multiple resistance to at least 9 out of 16 antibiotics tested. Lowest resistance rates were found for piperacillin (9.7 %) and ciprofloxacin (24.4 %), whereas only piperacillin/tazobactam and trimethoprim/sulfamethoxazole showed 100 % activity. More than half of isolates carried bla (IND)-type gene, including 2 isolates carrying bla (IND-2) and 21 carrying bla (IND-7), that was identified as a major MBL genotype in isolates from Adriatic Sea. RAPD typing of IND-producing isolates revealed 6 major groups with no predominant clone in population. The presence of multidrug resistant and IND-producing C. indologenes in marine environment, including marine fauna, pose a risk for transmitting this opportunistic pathogen to humans through recreation or consummation of seafood. In addition, the antibiotic susceptibility test results have practical relevance for empirical treatment of C. indologenes infections.

Low producer MBL genotypes are associated with susceptibility to systemic lupus erythematosus in Odisha, India

Variants of MBL gene have been associated with autoimmune disorders. The aim of this study was to explore whether common polymorphisms in MBL gene are associated with susceptibility to systemic lupus erythematosus (SLE) and its clinical manifestations in a cohort from eastern India. A total of 108 female SLE patients and 105 age, sex, and ethnically matched healthy controls were enrolled in the study. MBL2 codon and promoter polymorphisms were genotyped by AS-PCR and dARMS PCR, respectively. Plasma level of MBL was quantified by ELISA. Higher frequency of BB genotype and minor allele (B) was observed in patients of SLE compared to healthy controls (BB genotype: P = 0.0002; OR = 5.75, 95% CI = 2.09-15.76, B allele: P < 0.0001; OR = 2.78, 95% CI = 1.66-4.64). MBL codon 54, H-550L, Y-221X polymorphisms and combined MBL genotypes contributed to plasma MBL levels. Prevalence of MBL low producer genotype (LXA/LYB, LYB/LYB and LXB/LXB) was significantly higher in SLE patients compared to healthy control. (P = 0.005; OR = 3.09, 95% CI = 1.38-6.91). On analysis of clinical manifestations, MBL low producer genotype was significantly associated with autoimmune haemolytic anaemia (P = 0.006; OR = 13.06). Results of the present study indicate MBL2 variants as possible risk factors for development of SLE and clinical manifestation in eastern India.

Role of genetic polymorphisms in factor H and MBL genes in Tunisian patients with immunoglobulin A nephropathy

The molecular mechanisms of IgA nephropathy (IgAN) remain poorly understood. Several different polymorphic genes have been investigated in order to demonstrate their possible association with this disease. It is evident that mainly alternative and lectin pathways complement activation and play an important role in renal injury of IgAN. This study was conducted to determine eventual deficiencies of factor H in the SCR20 gene region and to look for a possible association between the polymorphism (+54) exon 1 of the MBL gene and the predisposition in Tunisian patients with IgAN. We then evaluated the effects of these FH mutations and/or this MBL polymorphism on nephropathy susceptibility and progression. Polymorphism A/B (+54) in the exon1 of the MBL gene and analysis within the C-terminal domain of the protein SCR20 in the exon 22 of the factor H (FH) gene were conducted in 36 sporadic IgAN Tunisian patients and 117 age and gender matched healthy subjects recruited from blood donors, by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing respectively. The analysis of the Gly54Asp (+54) mutation of the MBL gene according to the criteria of gravity of the IgAN reveals that the patients with genotype AB present more frequently with end-stage renal disease (ESRD) compared with those of genotype AA [OR: 8, CI (1.74-54.49), P = 0.019]. Moreover, the variant allele B was statistically more frequent than the allele A in patients with an association with initial arterial high blood pressure, ESRD and class V of the Haas classification compared to those without this association (P = 0.009). The direct sequencing of exon 22 (SCR 20) of FH gene did not reveal any abnormal mutational deficiency for this factor in all patients and controls. The data did not support the hypothesis that FH is a susceptibility factor for the IgAN. However the data did show there was an association between AB (+54) exon1 MBL genotype and severe sporadic forms of this disease in Tunisian patients. Because of the small number of subjects studied, a much larger cohort of IgAN patients with varying severity of the disease and its progression would seem necessary to confirm these findings.

Structural Polymorphisms in the Mannose-Binding Lectin Gene Are Associated with Juvenile Idiopathic Arthritis

To investigate the possible association between polymorphisms of the mannose-binding lectin gene (MBL2) and susceptibility to juvenile idiopathic arthritis (JIA). We performed a case-control association study including 118 Hungarian patients with JIA and 118 sex-matched healthy controls. MBL genotyping for the 3 mutant structural alleles at codons 54 (B), 57 (C), and 52 (D) in exon 1 and the promoter polymorphisms at position -550 (HL) and -221 (YX) were carried out by real-time PCR allelic discrimination. Serum level of MBL was determined by ELISA. Variant allele frequencies of both codon 52 and 57 polymorphisms in the MBL2 gene were significantly overrepresented in JIA (p=0.001 and p=0.004, respectively). The frequency of low MBL genotypes (XA/XA, YA/YO, XA/YO, and YO/YO) in JIA was higher than that in healthy controls (p=0.001). Serum MBL concentrations were found to be significantly lower in JIA patients versus control subjects (p=0.001). The 2 promoter polymorphisms and codon 54 SNP of the MBL2 gene were not associated with JIA. Our findings suggest that genetically determined low MBL levels may predispose children to JIA in a Hungarian population. These data warrant further research to investigate the role of the lectin-dependent complement system in the pathogenesis of JIA.

Analysis of resistant genes of beta-lactam antibiotics from Pseudomonas aeruginosa in pediatric patients

To analyze the antibiotic resistance of the Pseudomonas aeruginosa (PA) isolated from pediatric patients and the resistant genes of beta-lactam antibiotics thereof. 146 PA strains were isolated from pediatric patients. Agar dilution method recommended by the Clinical and Laboratory Standards Institute was used to examine the minimum inhibitory concentrations (MICs) of 12 antimicrobial agents, including the penicillins, third and fourth genet ration cephalosporins, carbapenemase, Aztreonam, beta-lactamase inhibitors, quinolones, and aminoglycosides. PCR was used to detect the expression of the genes TEM, SHV, OXA, PER, GES, CTX-M, IMP, VIM, DHA, MIR, FOX, and oprD2. The multi-drug resistance rates against different antibiotic were high among the 146 PA strains. The rates of imipenem and meropenem resistance were 41.1% and 35.6% respectively. Among the 146 PA strains, 46 (31.5%) were positive for the MBL genotype; 38 (82.6%) carried the blaIMP gene, 8 (17.4%) carried the blaVIM gene, and 114 (78.1%) were oprD2 negative. The genes TEM, SHV, OXA, CTX-M, PER, VEB, GES, FOX, MIR, and DHA were not found in all strains. Many PA isolated from pediatric patients carry the genes IMP or VIM and losses oprD2 gene related to the expression of the outer membrane porin OprD2. The loss of the gene oprD2 is essential mechanism of beta-lactam antibiotics resistance in PA.

Association of Mannose Binding Lectin (MBL-2) Deficiency with Pulmonary Infection after Allogeneic Hematopoietic Stem Cell Transplantation (HSCT).

Background: Low MBL2 concentration and MBL2 genotype variants have been associated with an increased risk of infection in various clinical settings. Pulmonary infection is a major complication of HSCT. We examined the relationship of MBL genotypes with post-engraftment bacterial (B-PNA) and fungal (F-PNA) pneumoniaMethods: Retrospective review of 236 non-consecutive, non-selected patients who underwent HSCT at MSKCC from 1/1/2000–4/30/2007. Microbiologically confirmed infections and pneumonias were recorded. Antifungal prophylaxis consisted of fluconazole 400 mg daily. Patients at high risk for mold infection received mold-active prophylaxis. After 1/1/2006 voriconazole was the first line anti-mold prophylaxis. Genotype was determined by PR-Melting Curve Analysis on blood or buccal swab specimens. MBL genotype was classified as wild-type: A/A (MBL-sufficient, MBL-S) or variant-type: A/O, O/O (MBL deficient, MBL-D). Patients were followed for up to 2 years. Statistical analysis: Fisher's Exact test was used to compare the incidence rate between MBL-S and MBL-D patients. Multivariate logistical regression models were used to investigate the relationship between bacterial or fungal pneumonia and MBL genotype, matched related donor (MRD), myeloablative conditioning (MC) peripheral blood as stem cell source (PBSC), acute GVHD grade 2–4 (aGVHD). The results from Maximum Likelihood Estimates were summarized.Results: Transplant characteristics: 80% MC, 76% PBSC, 48.6% MRD. Incidence of aGVHD: 22.4%. MBL genotypes: One-hundred and forty-two (60%) patients were homozygous for wild-type MBL2 (AA), 85(36%) were heterozygous (A/0) and 9 (3.8%) were homozygous for variant genotypes (OO). Transplant characteristics, rates of GVHD, relapse-free and overall survival were similar between MBL-D and MBL-S. There was higher incidence of overall bacterial infections in MBL-D compared to MBL-S pts (47.87% vs 36.62%, p=0.1049). MBL-D had a higher incidence of B-PNA (12.7% vs 4.9%, p=0.048). In multivariate logistic regression analysis, MBL-D(p=0.04) and aGVHD(p=0.06) were likely associated with B-PNA. Rates of overall fungal infections and F-PNA were similar [among MBL-D and MBL-S pts (12.77% vs 9.86%, p=0.5277) and (8.51% vs 7.75%, p=0.1049) respectively]. In multivariate logistic regression analysis only aGVHD was statistically significantly associated with F-PNA p=0.0002.Conclusions: 1) MBL-D genotype was likely associated with increased risk of bacterial pneumonia. 2) MBL-D and aGVHD were risk factors for B-PNA. 3) Further analyses are in progress to evaluate the effect of MBL-D on fungal pneumonia in patients who received mold prophylaxis versus patients who did not receive mold prophylaxis. 4) Prospective studies are needed to assess the relative contribution of MBL-D genotype on the risk of pulmonary infection in HSCT.

Association of MBL2 genotypes wtih infections and outcome after allogeneic stem cell transplantation

7100 Background: Low MBL2 concentration and MBL2 genotype variants have been associated with an increased risk of infection. Our objective was to correlate MBL2 genotypes with specific infections and outcome of HSCT. Methods: 125 non- consecutive, non-selected HSCT were examined. Patients were classified as high or low risk group based on status of underlying disease. Antifungal prophylaxis consisted of fluconazole 400 mg daily. Patients on steroids received mould prophylaxis. There was no routine antibacterial prophylaxis. Microbiologically confirmed infections were recorded. Genotype was determined by PR-Melting Curve Analysis on blood or buccal swab specimens. MBL genotype was classified as wild-type: A/A (MBL-sufficient, MBL-S) or variant-type: A/O, O/O (MBL deficient, MBL- D). Patients were followed for up to 2 years. Analyses of categorical variables were performed using the Fisher exact test and the Log-Rank test for time to event. Results: Seventy-one (58.2%) patients were homozygous for wild-type MBL2 (AA), 43 (35.3%) were heterozygous (A/0) and 8 (6.5%) were homozygous for variant genotypes (OO). MBL-D group had higher incidence of fungal infections (20% vs 7%, p=0.05), and in particular Aspergillosis (12% vs 3%, p=0.05). MBL-D was associated with a trend for higher rates of bacterial infections (63% vs 46%, p=0.10) and total number of bacterial infections (p=0.10). Rates of respiratory and enteric viral infections or CMV were similar in MBL-D and MBL-S groups (41% vs 38%, p=0.9 and 58% vs. 54% p=1.0 respectively). Patients with MBL-D genotype were at a disadvantage in relapse-free (RFS) and overall survival (OS), (p&lt;0.01 and p=.08). This disadvantage was also observed when stratified by disease risk groups. The estimated 2-year relapse-free survival rate was 30% compared to 53% for MBL-D vs. MBL-S patients (p&lt;0.01). Conclusions: 1) Patients with variant MBL genotype (MBL-D) had a trend for increased incidence and number of bacterial infections. 2) MBL-D genotype and graft versus host disease were risk factors for aspergillosis. 3) MBL-D genotype was associated with worse overall survival and relapse free survival post HSCT. These data suggest that MBL-D patients have impaired immune function compared with MBL-S patients and is consistent with animal data. [Table: see text]

Mannose-Binding Lectin Gene and Promoter Polymorphism in Visceral Leishmaniasis Caused by Leishmania infantum

Visceral leishmaniasis is an infectious disease caused by various species of Leishmania and Leishmania infantum is known to be associated with VL in Iran. Different factors can consider risk factors for VL that some remain unknown. The aim of present study is to determine the distribution of the alleles ofmannose-binding lectin gene codon 52, 54, 57 and promoter variants H/L, X/Y, P and Q in confirmed VL patients while compares then with normal controls and seek correlation between these variants and confirmed VL patients. Fifty eight confirmed VL patients blood samples were compared with one hundred and twenty normal controls from Azarbaijan population of Iran. MBL genotypes were investigated by polymerase chain reaction and restriction fragment length polymorphism. Allelic and genotypic frequency of the polymorphism at promoters and genes didn't show statistical differences in patients and normal controls, but frequency of alleles with high MBL concentration in VL patients was higher than controls (p = 0.03). We can conclude that normal alleles with high MBL serum level are risk factor for VL and defective alleles have protective role in VL.

Concordance of MBL protein concentrations, functional activities, and genotypes in a healthy control population

RATIONALE: MBL is a soluble oligomeric pattern recognition molecule that constitutes an important element in innate immune defense against a broad range of microorganisms. The binding of MBL to sugar motifs occurring on the surface of these microorganisms leads to the recruitment of MBL associated serine proteases (MASPs), which in complex with MBL activate complement via the MBL pathway. MBL-MASP complex deficiencies have been described in individuals and are mainly attributed to genetic polymorphisms. Individuals with MBL-MASP complex deficiencies have reduced or deficient complement activation via the MBL pathway, and in some, this condition leads to severe or recurrent infections. METHODS: In this study, the MBL protein concentration, functional activity and genotype of 30 individuals in a healthy control population were determined by ELISA, C4b deposition and real-time PCR, respectively. RESULTS: This study indicates that 90% (18/20) of individuals without a structural variant in exon 1 of the mbl2 gene have sufficient MBL protein concentrations (>1000 ng/mL) and function. The remaining 10% (2/20) of individuals without a structural variant who have sufficient MBL protein concentrations were determined to be deficient in MBL function. All individuals (10/10) with a structural variant have MBL levels that are characterized as deficient (<100 ng/mL) or reduced (<1000 ng/mL) and have deficient MBL function. CONCLUSIONS: The MBL protein concentration, functional activity and genotype data from 30 healthy controls were observed to be generally concordant. However, these data would suggest that determining MBL concentration, functional activity or genotype alone, is not sufficient to fully evaluate an individual's MBL status.