MBL2 polymorphism and risk of severe infections in multiple myeloma patients receiving high-dose melphalan and autologous stem cell transplantation

Current perspectives on interethnic variability in multiple myeloma: Single cell technology, population pharmacogenetics and molecular signal transduction

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This review discusses the emerging single cell technologies and applications in Multiple myeloma (MM), population pharmacogenetics of MM, resistance to chemotherapy, genetic determinants of drug-induced toxicity, molecular signal transduction.

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The role(s) of epigenetics and noncoding RNAs including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) that influence the risk and severity of MM are also discussed.

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It is understood that ethnic component acts as a driver of variable response to chemotherapy in different sub-populations globally.

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This review augments our understanding of genetic variability in ‘myelomagenesis’ and drug-induced toxicity, myeloma microenvironment at the molecular and cellular level, and developing precision medicine strategies to combat this malignancy.

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The emerging single cell technologies hold great promise for enhancing our understanding of MM tumor heterogeneity and clonal diversity.

Multiple myeloma (MM) is an aggressive cancer characterised by malignancy of the plasma cells and a rising global incidence. The gold standard for optimum response is aggressive chemotherapy followed by autologous stem cell transplantation (ASCT). However, majority of the patients are above 60 years and this presents the clinician with complications such as ineligibility for ASCT, frailty, drug-induced toxicity and differential/partial response to treatment. The latter is partly driven by heterogenous genotypes of the disease in different subpopulations. In this review, we discuss emerging single cell technologies and applications in MM, population pharmacogenetics of MM, resistance to chemotherapy, genetic determinants of drug-induced toxicity, molecular signal transduction, as well as the role(s) played by epigenetics and noncoding RNAs including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) that influence the risk and severity of the disease. Taken together, our discussions further our understanding of genetic variability in ‘myelomagenesis’ and drug-induced toxicity, augment our understanding of the myeloma microenvironment at the molecular and cellular level and provide a basis for developing precision medicine strategies to combat this malignancy.

Mannose-binding lectin gene polymorphism and the susceptibility of sepsis: A meta-analysis

Objective

To assess the association between the Mannose-binding lectin (MBL) gene polymorphism and the susceptibility to sepsis using a meta-analysis.

Methods

The publications were searched on PubMed, Embase, and Web of Science databases up to December 1, 2019 for relevant literature.

Results

A total of 32 studies (21 adult and 11 pediatric studies) were selected for analysis. Overall, in the three models of MBL +54 A/B gene polymorphisms, namely the dominant model BB + AB vs. AA ( p = 0.03), the recessive model BB vs. AB + AA ( p < 0.00001), and the allele model B vs. A ( p = 0.04), MBL +54 A/B was significantly related to the risk of sepsis. In the adult group, the MBL A/O gene polymorphism was associated with the risk of sepsis in the dominant model AO + OO vs. AA ( p = 0.006) as well as in the allele model O vs. A ( p = 0.04). The MBL +54 A/B gene polymorphism was significantly related to the risk of sepsis in the recessive model and, therefore, may increase the risk of sepsis. In the pediatric group, no polymorphic loci were significantly associated with sepsis in any of the three models. The results of the publication bias test demonstrated no publication bias in an unadjusted estimate of the relationship between MBL A/O and −211Y/X gene polymorphism and sepsis.

Conclusions

The polymorphisms of MBL that are related to the occurrence of sepsis are primarily A/O and +54 A/B, while −221Y/X and −550H/L have no clear relationship with the susceptibility of sepsis in various age groups or different models.

Components of the Lectin Pathway of Complement in Haematologic Malignancies

The complement system is activated cascadically via three distinct major routes: classical pathway (CP), alternative pathway (AP) or lectin pathway (LP). The unique factors associated with the latter are collectins (mannose-binding lectin, collectin-10, collectin-11), ficolins (ficolin-1, ficolin-2, ficolin-3) and proteins of the mannose-binding lectin-associated serine protease (MASP) family (MASP-1, MASP-2, MASP-3, MAp19, MAp44). Collectins and ficolins are both pattern-recognising molecules (PRM), reactive against pathogen-associated molecular patterns (PAMP) or danger-associated molecular patterns (DAMP). The MASP family proteins were first discovered as complexes with mannose-binding lectin (MBL) and therefore named MBL-associated serine proteases, but later, they were found to interact with ficolins, and later still, collectin-10 and collectin-11. As well as proteolytic enzymes (MASP-1, MASP-2, MASP-3), the group includes non-enzymatic factors (MAp19, MAp44). In this review, the association-specific factors of the lectin pathway with haematologic malignancies and related infections are discussed.

Low pre-transplant levels of mannose-binding lectin are associated with viral infections and mortality after haematopoietic allogeneic stem cell transplantation

BACKGROUND

Mannose-binding lectin (MBL) is a key component of innate immunity. Low serum MBL levels, related to promoter polymorphism and structural variants, have been associated with an increased risk of infection. The aim of this work was to analyse the incidence and severity of infections and mortality in relation to the MBL2 genotype and MBL levels in patients underwent allogeneic haematopoietic stem cell transplantation (Allo-HSCT).

RESULTS

This was a prospective cohort study of 72 consecutive patients underwent Allo-HSCT between January 2007 and June 2009 in a tertiary referral centre. Three periods were considered in the patients' follow-up: the early period (0-30 days after Allo-HSCT), the intermediate period (30-100 days after Allo-HSCT) and the late period (> 100 days after Allo-HSCT). A commercial line probe assay for MBL2 genotyping and an ELISA Kit were used to measure MBL levels. A total of 220 episodes of infection were collected in the 72 patients. No association between donor or recipient MBL2 genotype and infection was found. The first episode of infection presented earlier in patients with pre-transplant MBL levels of < 1000 ng/ml (median 6d vs 8d, p = 0.036). MBL levels < 1000 ng/ml in the pre-transplant period (risk ratio (RR) 2.48, 95% CI 1.00-6.13), neutropenic period (0-30 days, RR 3.28, 95% CI 1.53-7.06) and intermediate period (30-100 days, RR 2.37, 95% CI 1.15-4.90) were associated with increased risk of virus infection. No association with bacterial or fungal disease was found. Mortality was associated with pre-transplant MBL levels < 1000 ng/ml (hazard ratio 5.55, 95% CI 1.17-26.30, p = 0.03) but not with MBL2 genotype.

CONCLUSIONS

Patients who underwent Allo-HSCT with low pre-transplant MBL levels presented the first episode of infection earlier and had an increased risk of viral infections and mortality in the first 6 months post-transplant. Thus, pre-transplant MBL levels would be important in predicting susceptibility to viral infections and mortality and might be considered a biomarker to be included in the pre-transplantation risk assessment.

The Role of Complement Activating Collectins and Associated Serine Proteases in Patients With Hematological Malignancies, Receiving High-Dose Chemotherapy, and Autologous Hematopoietic Stem Cell Transplantations (Auto-HSCT)

We conducted a prospective study of 312 patients (194 with multiple myeloma, 118 with lymphomas) receiving high-dose conditioning chemotherapy and autologous hematopoietic stem cell transplantation (auto-HSCT). Polymorphisms of MBL2 and MASP2 genes were investigated and serial measurements of serum concentrations of mannose-binding lectin (MBL), CL-LK collectin and MASP-2 as well as activities of MBL-MASP-1 and MBL-MASP-2 complex were made. Serum samples were taken before conditioning chemotherapy, before HSCT and once weekly after (totally 4-5 samples); in minority of subjects also 1 and/or 3 months post transplantation. The results were compared with data from 267 healthy controls and analyzed in relation to clinical data to explore possible associations with cancer and with chemotherapy-induced medical complications. We found a higher frequency of MBL deficiency-associated genotypes (LXA/O or O/O) among multiple myeloma patients compared with controls. It was however not associated with hospital infections or post-HSCT recovery of leukocytes, but seemed to be associated with the most severe infections during follow-up. Paradoxically, high MBL serum levels were a risk factor for prolonged fever and some infections. The first possible association of MBL2 gene 3′-untranslated region polymorphism with cancer (lymphoma) in Caucasians was noted. Heterozygosity for MASP2 gene +359 A>G mutation was relatively frequent in lymphoma patients who experienced bacteremia during hospital stay. The median concentration of CL-LK was higher in myeloma patients compared with healthy subjects. Chemotherapy induced marked increases in serum MBL and MASP-2 concentrations, prolonged for several weeks and relatively slighter decline in CL-LK level within 1 week. Conflicting findings on the influence of MBL on infections following chemotherapy of myeloma and lymphoma have been reported. Here we found no evidence for an association between MBL deficiency and infection during the short period of neutropenia following conditioning treatment before HSCT. However, we noted a possible protective effect of MBL during follow-up, and suspected that to be fully effective when able to act in combination with phagocytic cells after their recovery.

Low circulating mannan-binding lectin levels correlate with increased frequency and severity of febrile episodes in myeloma patients who undergo ASCT and do not receive antibiotic prophylaxis

Patients with multiple myeloma (MM) who undergo autologous stem cell transplantation (ASCT) are susceptible to severe infections. Low levels of circulating mannan-binding lectin (MBL) are associated with increased risk of infection. In this prospective study, we evaluated 100 patients who underwent ASCT regarding the effect of MBL on the incidence and severity of febrile episodes. Seventeen patients had MBL levels <500 ng/mL (11 received antibiotic prophylaxis and 6 did not). Although there was no statistical difference regarding the development of febrile episodes between patients with low and normal MBL, among 17 patients with low MBL levels, six out of eleven patients who received antibiotic prophylaxis developed a febrile episode compared with six out of six patients who did not receive antibiotic prophylaxis and developed a febrile episode. Patients with low MBL levels who responded less frequently to first line antibiotic therapy required more frequent administration of a second more advanced line of antibiotics, independently of receiving or not prophylaxis, and required prolonged hospitalization. In the univariate analysis low MBL associated with shorter OS. Our results suggest that patient with low MBL levels should receive antibiotic prophylaxis to reduce the number of febrile episodes and raise the issue of MBL replacement for these patients.

Risk stratification and immunogenetic risk for infections following stem cell transplantation

Patients undergoing haematopoietic stem cell transplantation (HSCT) are highly exposed to infectious agents. However, it is not known why certain HSCT recipients rapidly develop severe infections while other, despite similar immunosuppressive conditions, do not. Increasing evidence suggests that such differences may be due, in part, to polymorphisms in immune genes. Thus, the identification of genetic factors influencing susceptibility to infections in HSCT recipients may lead to the development of individualized management strategies. However, studies are challenged by several issues, including the relative small size of existing cohorts, the frequent use of prophylactic or preemptive antimicrobial agents, and the fact that genes responsible for immune functions can be inherited either from the donor or the host. Consequently, the major challenge for today's researchers is to overcome these limitations and find associations that are robust enough to be translated into reliable risk stratification strategies for infectious diseases.

Infections After High-Dose Chemotherapy and Autologous Hematopoietic Stem Cell Transplantation

Infection represents an important cause of morbidity after autologous hematopoietic stem cell transplantation (HSCT). Immunodeficiency is the key risk factor and results from interplay between the underlying disease and its therapy. Various defects in the immune system coexist in HSCT recipients. In the early post-transplant period, neutropenia, oral and gastrointestinal mucositis, and the presence of central venous catheters are the main risk factors. Bacterial infections predominate, and the agents and antibiotic susceptibility profiles vary widely in different regions. Invasive candidiasis is infrequent with fluconazole use, but the incidence of invasive aspergillosis is on the rise, mainly in patients receiving purine analogues or intensive chemotherapy before transplant. In the post-engraftment period, infections are less frequent, but may contribute to significant non-relapse mortality. The dynamics of immune reconstitution drives the risk for infection in this period. The most frequent infections are varicella-zoster virus disease and respiratory tract infections. Assessment of the risk of infection in each period and the identification of patients at higher risk of specific infections are critical to the appropriate management of infectious complications after autologous hematopoietic stem cell transplantation.

Mannose-binding lectin gene variants and infections in patients receiving autologous stem cell transplantation

Background

Serious infections are common in patients undergoing autologous stem cell transplantation (ASCT) mainly because of the effects of immunosuppression. The innate immune system plays an important role in the defense against different infections. Mannose binding lectin (MBL) is a central molecule of the innate immune system. There are several promoter polymorphisms and structural variants of the MBL2 gene that encodes for this protein. These variants produce low levels of MBL and have been associated with an increased risk for infections.

Methods

Prospective cohort study. The incidence, severity of infections and mortality in 72 consecutive patients with hematologic diseases who underwent ASCT between February 2006 and June 2008 in a tertiary referral center were analyzed according to their MBL2 genotype. INNO-LiPA MBL2 was used for MBL2 gene amplification and genotyping. Relative risks (RR) (IC95%) as measure of association were calculated. Multivariate analysis was performed using logistic regression.

Results

A statistically significant higher number of fungal infections was found in patients with MBL2 variants causing low MBL levels (21.1%versus1.9%, p=0.016). In this MBL2 variant group infection was more frequently the cause of mortality than in the MBL2 wild-type group (p=0.05). Although not statistically significant, there was a higher incidence of major infections in the MBL2 variant group as well as a higher number of infections caused by gram-positive bacteria.

Conclusions

Low-producer MBL2 genotypes were associated with an increased number of fungal infections in ASCT patients, which would suggest that MBL has a protective role against such infections. ASCT patients with MBL2 variant genotypes are more likely to die as a result of an infection.

Mannose-binding lectin polymorphisms and the risk of sepsis: evidence from a meta-analysis

Several studies have evaluated the association between mannose-binding lectin (MBL) polymorphisms and sepsis. However, the results are inconclusive and conflicting. To better understand the roles of MBL polymorphisms in sepsis, we conducted a comprehensive meta-analysis. All relevant studies were searched from PubMed, EMBASE and Web of Knowledge databases, with the last report up to 7 May 2013. Twenty-nine studies addressing four MBL polymorphisms (-550G/C, -221G/C, structure variant A/O, Gly54Asp) were analysed for susceptibility to sepsis and one study for sepsis-related mortality. Overall, significant associations between structure variant A/O and susceptibility to sepsis were observed for AO + OO vs. AA [odds ratio (OR) 1·27, 95% confidence interval (CI) 1·05-1·52, P = 0·01] and O vs. A (OR 1·19, 95% CI 1·02-1·40, P = 0·03). In subgroup analysis based on age group, increased risk was found in the paediatric group in the dominant model (OR 1·72, 95% CI 1·16-2·56, P = 0·007). Moreover, there was a slight association between the +54A/B polymorphism and susceptibility to sepsis in Caucasians (recessive model: OR 10·64, 95% CI 1·24-91·65, P = 0·03). However, no association was observed for -550G/C and -221G/C polymorphisms both overall and in subgroup analysis. For sepsis-related mortality, only one study suggested AO/OO was associated with in-hospital mortality in pneumococcal sepsis patients after controlling for confounding variables. Our meta-analysis indicated that MBL structure variants might be associated with susceptibility to sepsis but further studies with a large sample size should be conducted to confirm these findings.

Mannose-binding lectin genotype influences frequency and duration of infectious complications in children with malignancy

Children with cancer receiving identical treatment differ in their experience of infection, suggesting that variations in immunity may influence susceptibility to infection. Studies of the influence of mannose-binding lectin (MBL), an important component of the innate immune system, in children with febrile neutropenia (FN) have yielded conflicting results. We examined the role of MBL in infection susceptibility in the largest cohort of children with cancer reported to date. MBL levels were measured and genotyping performed on children (≤16 y) receiving chemotherapy for cancer in London, UK. Clinical data from FN episodes were recorded prospectively. MBL status was assessed in 269 children; 513 episodes of FN were captured from 211 patients. Patients with MBL2 polymorphisms experienced more FN episodes than wildtype genotype (median 2 vs. 1, respectively; P = 0.074) and more episodes with documented infection (P = 0.045). Patients experiencing multiple FN episodes had lower MBL levels (P = 0.036). MBL genotype influenced duration of episode in some groups: high-risk MBL-deficient patients spent up to 5 nights longer/episode in hospital than equivalent wildtypes. These results indicate that MBL deficiency influences both susceptibility to and outcome of FN episodes and may be most important in those patients at higher risk of complications of FN.

Mannan-binding lectin in malignancy

Complement may play a dual role in cancer: it may contribute either to the development or to the inhibition of tumour growth. Its components may be candidate biomarkers facilitating the disease detection, its progress or effectiveness of therapy. Additionally, complement deficiencies may increase the risk of infections and contribute to the higher mortality, especially in patients undergoing aggressive chemotherapy. In this paper, possible cancer associations of one of the factors activating complement via the lectin pathway, mannan-binding lectin (MBL), are discussed.

Antimicrobial therapy of febrile complications after high-dose chemotherapy and autologous hematopoietic stem cell transplantation--guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

More than 18,000 autolgous transplantation were performed in Europe in the year 2009. It as a routine procedure in experienced centres. Even if there is a low mortality rate, infections are a major issue after transplantation, occurring in more than 60 % of the patients. In this review we discuss all aspects of infections after autologous stem transplantation, including epidemiology, diagnostics, therapeutic algorithms, prophylaxis and supportive therapy.

Genetic variants and the risk for invasive mould disease in immunocompromised hematology patients

PURPOSE OF REVIEW

Single-nucleotide polymorphisms (SNPs) appear to influence the risk of invasive mould disease (IMD) in immunocompromised patients. This raises the question of whether genetic risk prediction can be used to alter clinical practice. This review focuses on the current status of genetic association studies regarding invasive fungal disease among hematology patients, with an emphasis on IMD.

RECENT FINDINGS

Many studies have shown that SNPs in genes encoding cytokines, chemokines, and their receptors can increase the risk for IMD. Greater emphasis has recently been placed on SNPs in pattern-recognition receptors, including Toll-like receptor 4 (TLR4) and dectin-1. An association has been found between SNPs in TLR4 and dectin-1 and invasive aspergillosis, which has been strengthened by biological evidence from in-vitro and in-vivo studies that showed a loss of function in the presence of the SNP. Nevertheless, despite improving our understanding of host antifungal defenses in immunocompromised hosts, clinical applicability is still a long way off. Current genetic associations need further validation, as virtually all studies suffer methodological limitations such as small sample size, heterogeneity of cohorts, selection bias, ill defined outcome measure, and statistical flaws, mainly the lack of adjustments for multiple comparisons.

SUMMARY

Genetic variations in immune genes are associated with the risk for IMD among hematology patients although inconsistencies are frequently reported. The next step will be to select consistent SNPs and test them for their value in assessing risk in larger, better designed multicenter studies that will necessitate collaboration of multiple institutions in national or international consortia.

Mannan-binding lectin deficiency - Good news, bad news, doesn't matter?

Mannan-binding lectin (MBL) deficiency has been classified as a commonly occurring immune disorder, affecting approximately 30% of the human population. MBL, being part of the innate immune system, supports the recognition of infectious pathogens by binding to carbohydrate moieties expressed on microorganisms and activates the lectin pathway of the complement system. MBL2 gene polymorphisms are associated with quantitative and qualitative MBL abnormalities in the serum. The clinical impact of MBL deficiency and its association to a wide variety of diseases has been extensively studied. The picture is puzzling as the studies suggest a detrimental or beneficial or no impact of low or high MBL serum levels on disease susceptibility. In this review we attempt to extract what is relevant from the literature and address controversial issues. We finally suggest that a comprehensive understanding of the role of MBL in human diseases requires considering its context-dependency.

Sepsis in acute myeloid leukaemia patients receiving high-dose chemotherapy: no impact of chitotriosidase and mannose-binding lectin polymorphisms

Infections after chemotherapy often cause significant morbidity in patients with acute myeloid leukaemia (AML). Chitotriosidase (CHIT) and mannose-binding lectin (MBL) are part of the innate immune system. Polymorphism in the CHIT-coding gene (CHIT1) may be associated with Gram-negative sepsis in children with AML, and polymorphism in the MBL-coding gene (MBL2) seems to modify the risk of infections in several patient groups. The purpose of this study was to investigate the possible associations between polymorphisms in CHIT1, MBL2 and sepsis in adult patients treated with high-dose chemotherapy for AML. We included 190 patients treated with 526 cycles of chemotherapy. The follow-up period was 6 months from the diagnosis of AML. Prophylactic antibiotics were not used. We identified 604 febrile episodes with 246 episodes of sepsis. Thirty-two patients (17%) either died from infection or infection was a major concomitant factor for death. No significant associations between CHIT1 polymorphism and sepsis (P = 0.85) or death caused by sepsis (P = 0.14) were found. Furthermore, no significant associations between MBL2 polymorphism and sepsis (P = 0.76) or death caused by sepsis (P = 0.24) were observed. The severe and long-lasting neutropenia and mucositis after chemotherapy may explain why the MBL system does not protect against sepsis in patients with AML. Replacement therapy with recombinant MBL is not likely to decrease the risk of sepsis in patients with AML.

Influence of MBL-2 mutations in the infection risk of patients with follicular lymphoma treated with rituximab, fludarabine, and cyclophosphamide

The employment of current treatments based on chemotherapy and immunotherapy leads to inmunosuppression. The presence of mutations or polymorphisms in genes related to immune system might involve an additional disadvantage. The aim of the present study was to analyze mannose-binding lectin (MBL-2 gene) mutations and their association with severe infections and event-free survival in patients diagnosed with follicular lymphoma, treated uniformly, in the clinical trial LNHF-03. The results of this trial showed impressive clinical efficacy but was complicated with 80 documented infectious episodes. Patients were classified into two genotypic groups, AA and AO/OO, based on their haplotypic inheritance. Neither the number of infectious episodes nor differences in event-free survival was found as a function of MBL-2 groups. Other factors, including the lymphoma malignancy and the immune alterations associated with the disease, should be considered responsible for this observation.

Influence of mannose-binding lectin genotypes and serostatus in allo-SCT: analysis of 131 recipients and donors

Mannan-binding lectin (MBL) deficiency is determined by MBL gene polymorphisms and is associated with an increased infection risk. To clarify the role of MBL in Allo-SCT, 131 recipients-donors were analysed. MBL genotypes were determined by PCR and heteroduplex analyses, MBL serum levels by ELISA, and MBL oligomers by western blotting. MBL levels <400 ng/ml were associated with increased susceptibility to fungal pneumonia (7/12 vs 35/111; P=0.04, adjusted P=0.002), HSV/VZV (7/12 vs 26/111; P=0.03), CMV reactivation and acute GVHD. Donor genotypes had no influence. Pre-SCT MBL levels corresponded to recipients' genotypes (P<0.001), changed significantly post-SCT, but were not influenced by donors' genotypes. MBL oligomer profiles were similar pre-/post-SCT. Cultured CD34+ cells were found not to synthesise MBL. In conclusion, low MBL levels pre-transplant predisposed patients to sepsis, fungal and viral infection. Donors' MBL genotypes did not influence infection rates. Prospective studies should clarify the importance of MBL as a prelude for MBL replacement after SCT.

Infectious complications after chemotherapy and stem cell transplantation in multiple myeloma: implications of Fc gamma receptor and myeloperoxidase promoter polymorphisms

Multiple myeloma is associated with a high risk of infections. We hypothesized that Fc gamma receptor (FCGR) and myeloperoxidase (MPO) promoter gene polymorphisms influence the risk of infections after induction chemotherapy (IC) and autologous stem cell transplantation (ASCT). Retrospectively, we analysed 136 patient courses of IC and 113 procedures of ASCT. Genetic analyses were made with PCR techniques on genomic DNA. The incidence rate ratio of sepsis during ASCT in patients homozygous for the G-129MPO promoter type was 0.30 (95% CI: 0.09-0.96). The G-463AMPO promoter polymorphism was not associated with the risk of infections. The polymorphisms of FCGR2A, FCGR3A and FCGR3B were not convincingly associated with infections. The NA1 variant of FCGR3B was strongly skewed with other risk factors, and the results in IC and ASCT were conflicting. Further studies of the G-129AMPO promoter as a potential risk modifier for infections are relevant.

Mannose-binding lectin status is associated with risk of major infection following myeloablative sibling allogeneic hematopoietic stem cell transplantation

Mannose-binding lectin (MBL) is a mediator of innate immunity that influences the risk of infection in a range of clinical settings. We previously reported associations between MBL2 genotype and infection in a retrospective study of myeloablative allogeneic hematopoietic stem cell transplantation (allo-HCT). However, other studies have been inconclusive, and the role of MBL in reduced-intensity conditioning (RIC) transplantation is unknown. Here we report a prospective study examining MBL2 genotype, MBL levels, and risk of major infection following HLA-matched sibling myeloablative (n = 83) and RIC (n = 59) HCT. Baseline MBL levels were higher in recipients than donors (P < .001), and recipient MBL levels increased during the peritransplantation period (P = .001), most notably in MBL2 wild-type individuals receiving myeloablative total body irradiation (mTBI). MBL2 coding mutations were associated with major infection in recipients receiving mTBI. The cumulative incidence of major infection in recipient harboring an MBL2 mutation receiving mTBI was 70.6%, compared with 31.1% of those without mutations not receiving mTBI (P = .01). MBL status was not associated with infection in RIC transplants. These results confirm the association of MBL status with risk of infection in myeloablative, TBI-conditioned transplantation. Studies examining the role of MBL replacement therapy to prevent infection in this setting should be considered.

Immunodeficiency and immunotherapy in multiple myeloma

Multiple myeloma is a malignant tumour of plasma cells that remains incurable for the vast majority of patients, with a median survival of 2-3 years. It is characterized by the patchy accumulation of tumour cells within bone marrow leading to variable anaemia, bone destruction, hypercalcaemia, renal failure and infections. Immune dysfunction is an important feature of the disease and leads to infections that are both a major cause of morbidity and mortality and may promote tumour growth and resistance to chemotherapy. Numerous defects of the immune system have been described in multiple myeloma although the relative clinical importance of these remains elusive. There has been considerable interest in the identification of an autologous response against myeloma. Although T cells and humoral responses directed against myeloma-associated antigens have been described, it is uncertain if the immune system plays a role in preventing or controlling myeloma cell growth. There is increasing interest in the potential role of immunotherapy but the success of these interventions is likely to be modified by the immunologically hostile environment associated with multiple myeloma. This review attempts to summarize the current knowledge relating to the immune defects found in multiple myeloma.

Complement activating soluble pattern recognition molecules with collagen-like regions, mannan-binding lectin, ficolins and associated proteins

Mannan-binding lectin (MBL), L-ficolin, M-ficolin and H-ficolin are all complement activating soluble pattern recognition molecules with recognition domains linked to collagen-like regions. All four may form complexes with four structurally related proteins, the three MBL-associated serine proteases (MASPs), MASP-1, MASP-2 and MASP-3, and a smaller MBL-associated protein (MAp19). The four recognition molecules recognize patterns of carbohydrate or acetyl-group containing ligands. After binding to the relevant targets all four are able to activate the complement system. We thus have a system where four different and/or overlapping patterns of microbial origin or patterns of altered-self may be recognized, but in all cases the signalling molecules, the MASPs, are shared. MASP-1 and MASP-3 are formed from one gene, MASP1/3, by alternative splicing generating two different mRNAs from a single primary transcript. Similarly MASP-2 and MAp19 are both generated from one gene, MASP-2/MAp19, by alternative splicing. A number of non-synonymous polymorphisms of the four recognition molecules and of the MASPs are known, and the implications of these alterations are being studied. The clinical impact of deficiencies will be discussed.

New directions in the genomics of allogeneic hematopoietic stem cell transplantation

Despite optimal supportive care and high-resolution HLA matching, complications such as GVHD and infection remain major barriers to the success of allogeneic HCT (allo-HCT). This has led to growing interest in the non-HLA genetic determinants of complications after allo-HCT. Most studies have examined genetic predictors of GVHD, relapse, and mortality and have focused on 3 main areas: minor histocompatibility antigen (miHAs), inflammatory mediators of GVHD, and more recently NK cell-mediated allorecognition. The genetic basis of other outcomes such as infection and drug toxicity are less well studied but are being actively investigated. High-throughput methodologies such as single nucleotide polymorphism arrays are enabling the study of hundreds of thousands of genetic markers throughout the genome and the interrogation of novel genetic variants such as copy number variations. These data offer the opportunity to better predict those at risk of complications and to identify novel targets for therapeutic intervention. This review examines the current data regarding the non-HLA genomics of allo-HCT and appraises the promises and pitfalls for integration of this new genetic information into clinical transplantation practice.