Extensive Ethnic Variation and Linkage Disequilibrium at the FCGR2/3 Locus: Different Genetic Associations Revealed in Kawasaki Disease

Effectiveness of two same-manufacturer intravenous immunoglobulin for Kawasaki disease

BACKGROUND

To investigate whether two brands of intravenous immunoglobulin (IVIG) from the same manufacturer lead to varied effects when administered to patients with Kawasaki disease.

(KD) METHODS

Clinical characteristics, laboratory data, IVIG response, and coronary arteries change were analyzed between two groups.

RESULTS

We included 158 KD cases. The mean age at KD diagnosis was 23 ± 1.39 (range, 2-95) months. In the first IVIG course, 18 (11.4 %) patients were unresponsive. TBSF (brand T) and Privigen (brand P) were administered to 94 and 64 patients, respectively. The brand P group had a significantly longer fever (P < 0.001) and hospitalization (P = 0.007) durations after the therapy and a higher number of IVIG unresponsiveness (P = 0.016) than the brand T group. In the multivariate logistic regression analysis, a high Formosa score (≥3, Odds ratio [OR], 4.939; 95 % confidence interval [CI], 1.199-20.337; P = 0.027), high levels of CRP (≥12 mg/L, OR: 4.257,95 % CI,1.265-14.322; P = 0.019), and treatment with brand P (OR, 3.621; 95 % CI, 1.029-12.677; P = 0.045) were independent risk factors for IVIG unresponsiveness.

CONCLUSIONS

Compared with brand T, brand P prolonged the fever and hospitalization durations after IVIG treatment and increased the proportion of IVIG treatment unresponsiveness, but it did not infer the coronary arteries sequelae.

Fcγ receptors and immunomodulatory antibodies in cancer

The discovery of both cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and programmed cell death protein 1 (PD1) as negative regulators of antitumour immunity led to the development of numerous immunomodulatory antibodies as cancer treatments. Preclinical studies have demonstrated that the efficacy of immunoglobulin G (IgG)-based therapies depends not only on their ability to block or engage their targets but also on the antibody's constant region (Fc) and its interactions with Fcγ receptors (FcγRs). Fc-FcγR interactions are essential for the activity of tumour-targeting antibodies, such as rituximab, trastuzumab and cetuximab, where the killing of tumour cells occurs at least in part due to these mechanisms. However, our understanding of these interactions in the context of immunomodulatory antibodies designed to boost antitumour immunity remains less explored. In this Review, we discuss our current understanding of the contribution of FcγRs to the in vivo activity of immunomodulatory antibodies and the challenges of translating results from preclinical models into the clinic. In addition, we review the impact of genetic variability of human FcγRs on the activity of therapeutic antibodies and how antibody engineering is being utilized to develop the next generation of cancer immunotherapies.

Genetic variations in low-to-medium-affinity Fcγ receptors and autoimmune neutropenia in early childhood in a Danish cohort

Autoimmune neutropenia (AIN) in early childhood is caused by autoantibodies directed against antigens on the neutrophil membrane and is a frequent cause of neutropenia in children. Association of AIN with Fcγ receptor (FCGR) 3B variants is well described. In this study, we investigate genetic variations in the FCGR locus and copy number variation of FCGR3B. A total of 130 antibody-positive AIN patients, 64 with specific anti-HNA-1a antibodies and 66 with broad-reacting anti-FcγRIIIb antibodies, were genotyped with a multiplex ligation probe assay and compared with healthy controls. Positive findings were confirmed with real-time q-PCR. We determined copy numbers of the FCGR2 and FCGR3 genes and the following SNPs: FCGR2A Q62W (rs201218628), FCGR2A H166R (rs1801274), FCGR2B I232T (rs1050501), FCGR3A V176F (rs396991), haplotypes for FCGR2B/C promoters (rs3219018/rs780467580), FCGR2C STOP/ORF and HNA-1 genotypes in FCGR3B (rs447536, rs448740, rs52820103, rs428888 and rs2290834). Generally, associations were antibody specific, with all associations being representative of the anti-HNA-1a-positive group, while the only association found in the anti-FcγRIIIb group was with the HNA-1 genotype. An increased risk of AIN was observed for patients with one copy of FCGR3B; the HNA genotypes HNA-1a, HNA-1aa or HNA-1aac; the FCGR2A 166H and FCGR2B 232I variations; and no copies of FCGR2B 2B.4. A decreased risk was observed for HNA genotype HNA-1bb; FCGR2A 166R; FCGR2B 232T; and one copy of FCGR2B promoter 2B.4. We conclude that in our Danish cohort, there was a strong association between variation in the FCGR locus and AIN. The findings of different genetic associations between autoantibody groups could indicate the presence of two different disease entities and disease heterogeneity.

Analysis of FCGR3A-p.176Val variants in women with recurrent pregnancy loss and the association with CD16a expression and anti-HLA antibody status

Natural Killer (NK) cells have been implicated in recurrent pregnancy loss (RPL). The p.Val176Phe (or Val158Phe) Single Nucleotide Polymorphism (SNP) in the FCGR3A gene encoding the FcγRIIIA or CD16a receptor has been associated with an enhanced affinity for IgG and stronger NK-mediated antibody-dependent cellular cytotoxicity. We hypothesized that the presence of at least one p.176Val variant associates with RPL and increased CD16a expression and alloantibodies e.g., against paternal human leukocyte antigen (HLA). In 50 women with RPL, we studied frequencies of the p.Val176Phe FCGR3A polymorphisms. Additionally, CD16a expression and anti-HLA antibody status were analyzed by flowcytometry and Luminex Single Antigens. In woman with RPL, frequencies were: 20% (VV), 42% (VF) and 38% (FF). This was comparable to frequencies from the European population in the NCBI SNP database and in an independent Dutch cohort of healthy women. NK cells from RPL women with a VV (22,575 [18731-24607]) and VF (24,294 [20157-26637]) polymorphism showed a higher expression of the CD16a receptor than NK cells from RPL women with FF (17,367 [13257-19730]). No difference in frequencies of the FCGR3A-p.176 SNP were detected when comparing women with or without class I and class II anti-HLA antibodies. Our study does not provide strong evidence for an association between the p.Val176Phe FCGR3A SNP and RPL.

FCGR2C: An emerging immune gene for predicting sepsis outcome

Background

Sepsis is a life-threatening disease associated with immunosuppression. Immunosuppression could ultimately increase sepsis mortality. This study aimed to identify the prognostic biomarkers related to immunity in sepsis.

Methods

Public datasets of sepsis downloaded from the Gene Expression Omnibus (GEO) database were divided into the discovery cohort and the first validation cohort. We used R software to screen differentially expressed genes (DEGs) and analyzed DEGs' functional enrichment in the discovery dataset. Immune-related genes (IRGs) were filtered from the GeneCards website. A Lasso regression model was used to screen candidate prognostic genes from the intersection of DEGs and IRGs. Then, the candidate prognostic genes with significant differences were identified as prognostic genes in the first validation cohort. We further validated the expression of the prognostic genes in the second validation cohort of 81 septic patients recruited from our hospital. In addition, we used four immune infiltration methods (MCP-counter, ssGSEA, ImmuCellAI, and CIBERSORT) to analyze immune cell composition in sepsis. We also explored the correlation between the prognostic biomarker and immune cells.

Results

First, 140 genes were identified as prognostic-related immune genes from the intersection of DEGs and IRGs. We screened 18 candidate prognostic genes in the discovery cohort with the lasso regression model. Second, in the first validation cohort, we identified 4 genes (CFHR2, FCGR2C, GFI1, and TICAM1) as prognostic immune genes. Subsequently, we found that FCGR2C was the only gene differentially expressed between survivors and non-survivors in 81 septic patients. In the discovery and first validation cohorts, the AUC values of FCGR2C were 0.73 and 0.67, respectively. FCGR2C (AUC=0.84) had more value than SOFA (AUC=0.80) and APACHE II (AUC=0.69) in evaluating the prognosis of septic patients in our recruitment cohort. Moreover, FCGR2C may be closely related to many immune cells and functions, such as B cells, NK cells, neutrophils, cytolytic activity, and inflammatory promotion. Finally, enrichment analysis showed that FCGR2C was enriched in the phagosome signaling pathway.

Conclusion

FCGR2C could be an immune biomarker associated with prognosis, which may be a new direction of immunotherapy to reduce sepsis mortality.

Comprehensive genetic and functional analyses of Fc gamma receptors influence on response to rituximab therapy for autoimmunity

BACKGROUND

Rituximab is widely used to treat autoimmunity but clinical response varies. Efficacy is determined by the efficiency of B-cell depletion, which may depend on various Fc gamma receptor (FcγR)-dependent mechanisms. Study of FcγR is challenging due to the complexity of the FCGR genetic locus. We sought to assess the effect of FCGR variants on clinical response, B-cell depletion and NK-cell-mediated killing in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).

METHODS

A longitudinal cohort study was conducted in 835 patients [RA = 573; SLE = 262]. Clinical outcome measures were two-component disease activity score in 28-joints (2C-DAS28CRP) for RA and British Isles Lupus Assessment Group (BILAG)-2004 major clinical response (MCR) for SLE at 6 months. B-cells were evaluated by highly-sensitive flow cytometry. Single nucleotide polymorphism and copy number variation for genes encoding five FcγRs were measured using multiplex ligation-dependent probe amplification. Ex vivo studies assessed NK-cell antibody-dependent cellular cytotoxicity (ADCC) and FcγR expression.

FINDINGS

In RA, carriage of FCGR3A-158V and increased FCGR3A-158V copies were associated with greater 2C-DAS28CRP response (adjusted for baseline 2C-DAS28CRP). In SLE, MCR was associated with increased FCGR3A-158V, OR 1.64 (95% CI 1.12-2.41) and FCGR2C-ORF OR 1.93 (95% CI 1.09-3.40) copies. 236/413 (57%) patients with B-cell data achieved complete depletion. Homozygosity for FCGR3A-158V and increased FCGR3A-158V copies were associated with complete depletion in combined analyses. FCGR3A genotype was associated with rituximab-induced ADCC, and increased NK-cell FcγRIIIa expression was associated with improved clinical response and depletion in vivo. Furthermore, disease status and concomitant therapies impacted both NK-cell FcγRIIIa expression and ADCC.

INTERPRETATION

FcγRIIIa is the major low affinity FcγR associated with rituximab response. Increased copies of the FCGR3A-158V allele (higher affinity for IgG1), influences clinical and biological responses to rituximab in autoimmunity. Enhancing FcγR-effector functions could improve the next generation of CD20-depleting therapies and genotyping may stratify patients for optimal treatment protocols.

FUNDING

Medical Research Council, National Institute for Health and Care Research, Versus Arthritis.

MicroRNAs in Kawasaki disease: An update on diagnosis, therapy and monitoring

Kawasaki disease (KD) is an acute autoimmune vascular disease featured with a long stage of febrile. It predominantly afflicts children under 5 years old and causes an increased risk of cardiovascular combinations. The onset and progression of KD are impacted by many aspects, including genetic susceptibility, infection, and immunity. In recent years, many studies revealed that miRNAs, a novel class of small non-coding RNAs, may play an indispensable role in the development of KD via differential expression and participation in the central pathogenesis of KD comprise of the modulation of immunity, inflammatory response and vascular dysregulation. Although specific diagnose criteria remains unclear up to date, accumulating clinical evidence indicated that miRNAs, as small molecules, could serve as potential diagnostic biomarkers and exhibit extraordinary specificity and sensitivity. Besides, miRNAs have gained attention in affecting therapies for Kawasaki disease and providing new insights into personalized treatment. Through consanguineous coordination with classical therapies, miRNAs could overcome the inevitable drug-resistance and poor prognosis problem in a novel point of view. In this review, we systematically reviewed the existing literature and summarized those findings to analyze the latest mechanism to explore the role of miRNAs in the treatment of KD from basic and clinical aspects retrospectively. Our discussion helps to better understand the pathogenesis of KD and may offer profound inspiration on KD diagnosis, treatment, and prognosis.

FCGR3A gene duplication, FcγRIIb-232TT and FcγRIIIb-HNA1a associate with an increased risk of vertical acquisition of HIV-1

Background

Some mother-to-child transmission (MTCT) studies suggest that allelic variations of Fc gamma receptors (FcγR) play a role in infant HIV-1 acquisition, but findings are inconsistent. To address the limitations of previous studies, the present study investigates the association between perinatal HIV-1 transmission and FcγR variability in three cohorts of South African infants born to women living with HIV-1.

Methods

This nested case-control study combines FCGR genotypic data from three perinatal cohorts at two hospitals in Johannesburg, South Africa. Children with perinatally-acquired HIV-1 (cases, n = 395) were compared to HIV-1-exposed uninfected children (controls, n = 312). All study participants were black South Africans and received nevirapine for prevention of MTCT. Functional variants were genotyped using a multiplex ligation-dependent probe amplification assay, and their representation compared between groups using logistic regression analyses.

Results

FCGR3A gene duplication associated with HIV-1 acquisition (OR = 10.27; 95% CI 2.00–52.65; P = 0.005) as did the FcγRIIb-232TT genotype even after adjusting for FCGR3A copy number and FCGR3B genotype (AOR = 1.72; 95%CI 1.07–2.76; P = 0.024). The association between FcγRIIb-232TT genotype and HIV-1 acquisition was further strengthened (AOR = 2.28; 95%CI 1.11–4.69; P = 0.024) if adjusted separately for FCGR2C c.134-96C>T. Homozygous FcγRIIIb-HNA1a did not significantly associate with HIV-1 acquisition in a univariate model (OR = 1.42; 95%CI 0.94–2.16; P = 0.098) but attained significance after adjustment for FCGR3A copy number and FCGR2B genotype (AOR = 1.55; 95%CI 1.01–2.38; P = 0.044). Both FcγRIIb-232TT (AOR = 1.83; 95%CI 1.13–2.97; P = 0.014) and homozygous FcγRIIIb-HNA1a (AOR = 1.66; 95%CI 1.07–2.57; P = 0.025) retained significance when birthweight and breastfeeding were added to the model. The common FCGR2A and FCGR3A polymorphisms did not associate with HIV-1 acquisition.

Conclusions

Collectively, our findings suggest that the FcγRIIb-232TT genotype exerts a controlling influence on infant susceptibility to HIV-1 infection. We also show a role for less studied variants–FCGR3A duplication and homozygous HNA1a. These findings provide additional insight into a role for FcγRs in HIV-1 infection in children.

Gut Microbiota Dysbiosis in Childhood Vasculitis: A Perspective Comparative Pilot Study

Kawasaki disease (KD) and Henoch–Schönlein purpura (HSP) are the most frequent vasculitis in childhood. For both, a multifactorial mechanism has been hypothesised, with an abnormal immune response in genetically predisposed children. Gut microbiota (GM) alterations might trigger the hyperimmune reaction. Our aim was to explore the GM in KD and compare it with the GM of HSP and febrile children. Children diagnosed with KD, HSP and non-KD febrile illness (F) were enrolled. GM was profiled by 16S rRNA gene sequencing and compared with the profiles of healthy children from previous studies. We enrolled 13 KD, 10 HSP and 12 F children. Their GM significantly differed from controls, with an overall reduction in the relative abundance of beneficial taxa belonging to the Ruminococcaceae and Lachnospiraceae families. Potential KD and HSP signatures were identified, including smaller amounts of Dialister in the former, and Clostridium and Akkermansia in the latter. Notably, the GM structures of KD, HSP and F patients stratified by abdominal involvement, with more severe dysbiosis in those suffering from intestinal symptoms. This is the first study analysing GM in a mostly Caucasian cohort of KD and HSP children. Our data could open up new opportunities for childhood vasculitis treatment.

Fc receptors and the diversity of antibody responses to HIV infection and vaccination

The development of an effective vaccine against HIV is desperately needed. The successive failures of HIV vaccine efficacy trials in recent decades have shown the difficulty of inducing an appropriate protective immune response to fight HIV. Different correlates of antibody parameters associated with a decreased risk of HIV-1 acquisition have been identified. However, these parameters are difficult to reproduce and improve, possibly because they have an intricate and combined action. Here, we describe the numerous antibody (Ab) functions associated with HIV-1 protection and report the interrelated parameters regulating their complex functions. Indeed, besides neutralizing and Fc-mediated activity, additional factors such as Ab type, concentration and kinetics of induction, and Fc-receptor expression and binding capacity also influence the protective effect conferred by Abs. As these parameters were described to be associated with ethnicity, age and sex, these additional factors must be considered for the development of an effective immune response. Therefore, future vaccine designs need to consider these multifaceted Ab functions together with the demographic attributes of the patient populations.

FCGR2A-HH Gene Variants Encoding the Fc Gamma Receptor for the C-Reactive Protein Are Associated with Enhanced Monocyte CD32 Expression and Cardiovascular Events’ Recurrence after Primary Acute Coronary Syndrome

Fcγ receptors (FcγRs) interact with the C-reactive protein (CRP) and mediate activation of inflammation-related pathogenic mechanisms affecting cardiovascular health. Our study evaluated whether FcγRIIA and FcγRIIIA profiles are associated with the recurrence of adverse cardiovascular events during the first year after a primary acute coronary syndrome (ACS). The primary endpoint was the recurrence of cardiovascular events (RCE), identified as a composite outcome comprising acute heart failure (AHF) and major adverse cardiovascular events (MACE). We obtained blood samples of 145 ACS patients to measure hsCRP circulating levels, to identify FcγRIIA-131RH rs1801274 and FcγRIIIA-158FV rs396991 polymorphisms, to analyze circulating monocytes and NK cell subsets expressing CD16 and CD32, and to detect serum-mediated FCGR2A-HH activation by luciferase reporter assays. The hsCRP, CD32-expression, and Fc-R mediated activation levels were similar in all patients regardless of their MACE risk. In contrast, the hsCRP levels and the proportion of CD14+ circulating monocytes expressing the CD32 receptor for CRP were significantly higher in the patients who developed AHF. The FCGR2A rs1801274 HH genotype was significantly more common in patients who developed RCE and MACE than in RCE-free patients and associated with an enhanced percentage of circulating CD32+CD14+ monocytes. The FCGR2A-HH genotype was identified as an independent predictor of subsequent RCE (OR, 2.7; p = 0.048; CI, 1.01–7.44) by multivariate analysis. These findings bring preliminary evidence that host FCGR2A genetic variants can influence monocyte CD32 receptor expression and may contribute to the fine-tuning of CD32-driven chronic activating signals that affect the risk of developing RCEs following primary ACS events.

An HIV Vaccine Protective Allele in FCGR2C Associates With Increased Odds of Perinatal HIV Acquisition

In the Thai RV144 HIV-1 vaccine trial, a three-variant haplotype within the Fc gamma receptor 2C gene (FCGR2C) reduced the risk of HIV-1 acquisition. A follow-on trial, HVTN702, of a similar vaccine candidate found no efficacy in South Africa, where the predominant population is polymorphic for only a single variant in the haplotype, c.134-96C>T (rs114945036). To investigate a role for this variant in HIV-1 acquisition in South Africans, we used the model of maternal-infant HIV-1 transmission. A nested case-control study was conducted of infants born to mothers living with HIV-1, comparing children with perinatally-acquired HIV-1 (cases, n = 176) to HIV-1-exposed uninfected children (controls, n = 349). All had received nevirapine for prevention of mother-to-child transmission. The FCGR2C copy number and expression variants (c.-386G>C, c.-120A>T c.169T>C, and c.798+1A>G) were determined using a multiplex ligation-dependent probe amplification assay and the c.134-96C>T genotype with Sanger sequencing. The copy number, genotype and allele carriage were compared between groups using univariate and multivariate logistic regression. The FCGR2C c.134-96C>T genotype distribution and copy number differed significantly between HIV-1 cases and exposed-uninfected controls (P = 0.002, P _Bonf = 0.032 and P = 0.010, P _Bonf = > 0.05, respectively). The FCGR2C c.134-96T allele was overrepresented in the cases compared to the controls (58% vs 42%; P = 0.001, P _Bonf = 0.016). Adjusting for birthweight and FCGR2C copy number, perinatal HIV-1 acquisition was associated with the c.134-96C>T (AOR = 1.89; 95% CI 1.25-2.87; P = 0.003, P _Bonf = 0.048) and c.169C>T (AOR = 2.39; 95% CI 1.45-3.95; P = 0.001, P _Bonf = 0.016) minor alleles but not the promoter variant at position c.-386G>C. The c.134-96C>T variant was in strong linkage disequilibrium with the c.169C>T variant, but remained significantly associated with perinatal acquisition when adjusted for c.169C>T in multivariate analysis. In contrast to the protective effect observed in the Thai RV144 trial, we found the FCGR2C variant c.134-96T-allele associated with increased odds of perinatal HIV-1 acquisition in South African children. These findings, taken together with a similar deleterious association found with HIV-1 disease progression in South African adults, highlight the importance of elucidating the functional relevance of this variant in different populations and vaccination/disease contexts.

Remodeling the Tumor Myeloid Landscape to Enhance Antitumor Antibody Immunotherapies

Among the diverse tumor resident immune cell types, tumor-associated macrophages (TAMs) are often the most abundant, possess an anti-inflammatory phenotype, orchestrate tumor immune evasion and are frequently associated with poor prognosis. However, TAMs can also be harnessed to destroy antibody-opsonized tumor cells through the process of antibody-dependent cellular phagocytosis (ADCP). Clinically important tumor-targeting monoclonal antibodies (mAb) such as Rituximab, Herceptin and Cetuximab, function, at least in part, by inducing macrophages to eliminate tumor cells via ADCP. For IgG mAb, this is mediated by antibody-binding activating Fc gamma receptors (FcγR), with resultant phagocytic activity impacted by the level of co-engagement with the single inhibitory FcγRIIb. Approaches to enhance ADCP in the tumor microenvironment include the repolarization of TAMs to proinflammatory phenotypes or the direct augmentation of ADCP by targeting so-called 'phagocytosis checkpoints'. Here we review the most promising new strategies targeting the cell surface molecules present on TAMs, which include the inhibition of 'don't eat me signals' or targeting immunostimulatory pathways with agonistic mAb and small molecules to augment tumor-targeting mAb immunotherapies and overcome therapeutic resistance.

Role of Burkholderia pseudomallei-Specific IgG2 in Adults with Acute Melioidosis, Thailand

Melioidosis is a life-threatening infectious disease caused by the gram-negative bacillus Burkholderia pseudomallei. An effective vaccine is needed, but data on protective immune responses in human melioidosis are lacking. We used ELISA and an antibody-dependent cellular phagocytosis assay to identify the major features of protective antibodies in patients with acute melioidosis in Thailand. We found that high levels of B. pseudomallei–specific IgG2 are associated with protection against death in a multivariable logistic regression analysis adjusting for age, diabetes, renal disease, and neutrophil count. Serum from melioidosis survivors enhanced bacteria uptake into human monocytes expressing FcγRIIa-H/R131, an intermediate-affinity IgG2-receptor, compared with serum from nonsurvivors. We did not find this enhancement when using monocytes carrying the low IgG2–affinity FcγRIIa-R131 allele. The findings indicate the importance of IgG2 in protection against death in human melioidosis, a crucial finding for antibody-based therapeutics and vaccine development.

FCGR Genetic Variation in Two Populations From Ecuador Highlands-Extensive Copy-Number Variation, Distinctive Distribution of Functional Polymorphisms, and a Novel, Locally Common, Chimeric FCGR3B/A (CD16B/A) Gene

Fcγ receptors (FcγR), cell-surface glycoproteins that bind antigen-IgG complexes, control both humoral and cellular immune responses. The FCGR locus on chromosome 1q23.3 comprises five homologous genes encoding low-affinity FcγRII and FcγRIII, and displays functionally relevant polymorphism that impacts on human health. Recurrent events of non-allelic homologous recombination across the FCGR locus result in copy-number variation of ~82.5 kbp-long fragments known as copy-number regions (CNR). Here, we characterize a recently described deletion that we name CNR5, which results in loss of FCGR3A, FCGR3B, and FCGR2C, and generation of a recombinant FCGR3B/A gene. We show that the CNR5 recombination spot lies at the beginning of the third FCGR3 intron. Although the FCGR3B/A-encoded hybrid protein CD16B/A reaches the plasma membrane in transfected cells, its possible natural expression, predictably restricted to neutrophils, could not be demonstrated in resting or interferon γ-stimulated cells. As the CNR5-deletion was originally described in an Ecuadorian family from Llano Grande (an indigenous community in North-Eastern Quito), we characterized the FCGR genetic variation in two populations from the highlands of Ecuador. Our results reveal that CNR5-deletion is relatively frequent in Llano Grande (5 carriers out of 36 donors). Furthermore, we found a high frequency of two strong-phagocytosis variants: the FCGR3B-NA1 haplotype and the CNR1 duplication, which translates into an increased FCGR3B and FCGR2C copy-number. CNR1 duplication was particularly increased in Llano Grande, 77.8% of the studied sample carrying at least one such duplication. In contrast, an extended haplotype CD16A-176V – CD32C-ORF+2B.2 – CD32B-2B.4 including strong activating and inhibitory FcγR variants was absent in Llano Grande and found at a low frequency (8.6%) in Ecuador highlands. This particular distribution of FCGR polymorphism, possibly a result of selective pressures, further confirms the importance of a comprehensive, joint analysis of all genetic variations in the locus and warrants additional studies on their putative clinical impact. In conclusion, our study confirms important ethnic variation at the FCGR locus; it shows a distinctive FCGR polymorphism distribution in Ecuador highlands; provides a molecular characterization of a novel CNR5-deletion associated with CD16A and CD16B deficiency; and confirms its presence in that population.

Treatment-associated hemolysis in Kawasaki disease: association with blood-group antibody titers in IVIG products

Hemolytic anemia resulting from IV Immunoglobulin (IVIG) treatment can be a serious complication, especially for those with underlying conditions with a high level of inflammation and after administration of high IVIG dosages, such as Kawasaki disease (KD), a multisystem vasculitis affecting young children. This hemolysis is caused by antibodies against blood groups A and B, but the precise mechanism for hemolysis is not known. We performed a single center, partly retrospective, partly prospective study of a cohort of 581 patients who received IVIG for treatment of KD from 2006 to 2013. Factors associated with hemolysis were identified through univariable and multivariable logistic regression. Six IVIG preparations were assayed for their hemolytic effect with serological and cellular assays to clarify the mechanism of red cell destruction. During the study period, a sudden increase in the incidence of hemolysis was observed, which coincided with the introduction of new IVIG preparations in North America that contained relatively high titers of anti-A and anti-B. These blood-group-specific antibodies were of the immunoglobulin G2 (IgG2) subclass and resulted in phagocytosis by monocyte-derived macrophages in an FcγRIIa-dependent manner. Phagocytosis was increased in the presence of proinflammatory mediators that mimicked the inflammatory state of KD. An increased frequency of severe hemolysis following IVIG administration was caused by ABO blood-group-specific IgG2 antibodies leading to FcγRIIa-dependent clearance of erythrocytes. This increase in adverse events necessitates a reconsideration of the criteria for maximum titer (1:64) of anti-A and anti-B in IVIG preparations.

Platelet FcγRIIA in immunity and thrombosis: Adaptive immunothrombosis

Sepsis and autoimmune diseases remain major causes of morbidity and mortality. The last decade has seen a new appreciation of platelets in host defense, in both immunity and thrombosis. Platelets are first responders in the blood to microbes or non-microbial antigens. The role of platelets in physiologic immunity is counterbalanced by their role in pathology, for example, microvascular thrombosis. Platelets encounter microbes and antigens via both innate and adaptive immune processes; platelets also help to shape the subsequent adaptive response. FcγRIIA is a receptor for immune complexes opsonized by IgG or pentraxins, and expressed in humans by platelets, granulocytes, monocytes and macrophages. With consideration of the roles of IgG and Fc receptors, the host response to microbes and autoantigens can be called adaptive immunothrombosis. Here we review newer developments involving platelet FcγRIIA in humans and humanized mice in immunity and thrombosis, with special attention to heparin-induced thrombocytopenia, systemic lupus erythematosus, and bacterial sepsis. Human genetic diversity in platelet receptors and the utility of humanized mouse models are highlighted.

How Genetics Might Explain the Unusual Link Between Malaria and COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated coronavirus disease 2019 (COVID-19) pandemic has been the subject of a large number of studies in recent times. Here, starting from the evidence that in Italy, the areas with the lowest number of COVID-19 cases were those with the highest incidence of malaria in the early 1900's, we explore possible inverse relationships between malaria and COVID-19. Indeed, some genetic variants, which have been demonstrated to give an advantage against malaria, can also play a role in the incidence and severity of SARS-CoV-2 infections (e.g., the ACE2 receptor). To verify this scientific hypothesis, we here use public data from whole-genome sequencing (WGS) experiments to extrapolate the genetic information of 46 world populations with matched COVID-19 data. In particular, we focus on 47 genes, including ACE2 and genes which have previously been reported to play a role in malaria. Only common variants (>5%) in at least 30% of the selected populations were considered, and, for this subset, we correlate the intra-population allele frequency with the COVID-19 data (cases/million inhabitants), eventually pinpointing meaningful variants in 6 genes. This study allows us to distinguish between positive and negative correlations, i.e., variants whose frequency significantly increases with increasing or decreasing COVID-19 cases. Finally, we discuss the possible molecular mechanisms associated with these variants and advance potential therapeutic options, which may help fight and/or prevent COVID-19.

C-Reactive Protein Enhances IgG-Mediated Cellular Destruction Through IgG-Fc Receptors in vitro

Antibody-mediated blood disorders ensue after auto- or alloimmunization against blood cell antigens, resulting in cytopenia. Although the mechanisms of cell destruction are the same as in immunotherapies targeting tumor cells, many factors are still unknown. Antibody titers, for example, often do not strictly correlate with clinical outcome. Previously, we found C-reactive protein (CRP) levels to be elevated in thrombocytopenic patients, correlating with thrombocyte counts, and bleeding severity. Functionally, CRP amplified antibody-mediated phagocytosis of thrombocytes by phagocytes. To investigate whether CRP is a general enhancer of IgG-mediated target cell destruction, we extensively studied the effect of CRP on in vitro IgG-Fc receptor (FcγR)-mediated cell destruction: through respiratory burst, phagocytosis, and cellular cytotoxicity by a variety of effector cells. We now demonstrate that CRP also enhances IgG-mediated effector functions toward opsonized erythrocytes, in particular by activated neutrophils. We performed a first-of-a-kind profiling of CRP binding to all human FcγRs and IgA-Fc receptor I (FcαRI) using a surface plasmon resonance array. CRP bound these receptors with relative affinities of FcγRIa = FcγRIIa/b = FcγRIIIa > FcγRIIIb = FcαRI. Furthermore, FcγR blocking (in particular FcγRIa) abrogated CRP's ability to amplify IgG-mediated neutrophil effector functions toward opsonized erythrocytes. Finally, we observed that CRP also amplified killing of breast-cancer tumor cell line SKBR3 by neutrophils through anti-Her2 (trastuzumab). Altogether, we provide for the first time evidence for the involvement of specific CRP-FcγR interactions in the exacerbation of in vitro IgG-mediated cellular destruction; a trait that should be further evaluated as potential therapeutic target e.g., for tumor eradication.

Genetic biomarkers for intravenous immunoglobulin response in chronic inflammatory demyelinating polyradiculoneuropathy

BACKGROUND AND PURPOSE

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a clinical and electrophysiological heterogeneous immune-mediated polyneuropathy. Intravenous immunoglobulin (IVIg), corticosteroids, and plasma exchange are proven effective treatments for CIDP. The clinical response to IVIg is variable between patients and currently unexplained. Finding biomarkers related to treatment response can help to understand the diversity of CIDP and personalise treatment choice.

METHODS

We investigated whether genetic variation between patients may explain some of these differences in treatment response. Based on previous publications, we selected six candidate genes that might affect immune and axonal functions, IVIg metabolism, and treatment response in CIDP. Genetic variants were assessed in 172 CIDP patients treated with at least one course of IVIg (2 g/kg). A response to IVIg was defined by ≥1 grade improvement on the modified Rankin Scale. Blood samples were tested for variations in CNTN2, PRF1, FCGRT, FCGR2B, GJB1, and SH2D2A genes.

RESULTS

In univariate analysis, patients with the FCGR2B promoter variant 2B.4/2B.1 responded more often to IVIg than patients with the 2B.1/2B.1 variant (odds ratio [OR] = 6.9, 95% confidence interval [CI] = 1.6-30; p = 0.003). Patients with the p.(Ala91Val) variant of PRF1 were less often IVIg responsive (OR = 0.34, 95% CI = 0.13-0.91; p = 0.038). In multivariate analysis, both PRF1 and FCGR2B showed discriminative ability to predict the chance of IVIg response (area under the curve = 0.67).

CONCLUSIONS

Variations in PRF1 and the promoter region of FCGR2B are associated with the response to IVIg in CIDP. These findings, which require validation, are a first step towards the understanding of the heterogeneity in the treatment response in CIDP.

Identification of increased expression of activating Fc receptors and novel findings regarding distinct IgE and IgM receptors in Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is associated with expression and methylation of Fc gamma receptor genes. We characterized immunoglobulin A (IgA), IgE, IgG, and IgM receptor expression levels in KD.

METHODS

Fc receptor expression levels were characterized using GeneChip Human Transcriptome Array 2.0 (HTA 2.0) with 18 KD patients, 18 non-febrile controls, and 18 febrile controls. Another 48 control individuals and 46 patients with KD were measured using pyrosequencing for the methylation levels.

RESULTS

The mRNA expression levels of FCER1A and FCER2 were significantly lower in KD patients than in non-febrile controls and then rose following treatments with intravenous immunoglobulin (IVIG). Expression levels of FCER1G increased compared to the non-febrile subjects and then subsided after IVIG. FCER1A methylation was significantly lower among KD patients and even lower in KD patients with IVIG resistance. HTA analysis revealed higher mRNA levels of FCAR, FCGR1C, and FCGR2A in KD patients. FCMR mRNA expression levels were significantly lower in KD patients. FCMR expression levels rose after IVIG treatment. After IVIG, FCGR1A, B, and C decreased even lower than the febrile controls.

CONCLUSION

This is the first study indicating that IgA, IgE, IgG, and IgM receptors are associated with KD. We highlighted potential biomarkers related to Fc receptors and their regulation.

Polymorphisms in Fc Gamma Receptors and Susceptibility to Malaria in an Endemic Population

Repeated infections by Plasmodium falciparum result in a humoral response that could reduce disease symptoms and prevent the development of clinical malaria. The principal mechanism underlying this humoral response is that immunoglobulin G (IgG) binds directly to the parasites, thus causing their neutralization. However, the action of antibodies alone is not always sufficient to eliminate pathogens from an organism. One key element involved in the recognition of IgG that plays a crucial role in the destruction of the parasites responsible for spreading malaria is the family of Fc gamma receptors. These receptors are expressed on the surface of immune cells. Several polymorphisms have been detected in the genes encoding these receptors, associated with susceptibility or resistance to malaria in different populations. In this review, we describe identified polymorphisms within the family of Fc gamma receptors and the impact of these variations on the response of a host to infection as well as provide new perspectives for the design of an effective vaccine for malaria.

Plasticity in Pro- and Anti-tumor Activity of Neutrophils: Shifting the Balance

Over the last decades, cancer immunotherapies such as checkpoint blockade and adoptive T cell transfer have been a game changer in many aspects and have improved the treatment for various malignancies considerably. Despite the clinical success of harnessing the adaptive immunity to combat the tumor, the benefits of immunotherapy are still limited to a subset of patients and cancer types. In recent years, neutrophils, the most abundant circulating leukocytes, have emerged as promising targets for anti-cancer therapies. Traditionally regarded as the first line of defense against infections, neutrophils are increasingly recognized as critical players during cancer progression. Evidence shows the functional plasticity of neutrophils in the tumor microenvironment, allowing neutrophils to exert either pro-tumor or anti-tumor effects. This review describes the tumor-promoting roles of neutrophils, focusing on their myeloid-derived suppressor cell activity, as well as their role in tumor elimination, exerted mainly via antibody-dependent cellular cytotoxicity. We will discuss potential approaches to therapeutically target neutrophils in cancer. These include strategies in humans to either silence the pro-tumor activity of neutrophils, or to activate or enhance their anti-tumor functions. Redirecting neutrophils seems a promising approach to harness innate immunity to improve treatment for cancer patients.

Paediatric multisystem inflammatory syndrome temporally associated with SARS-CoV-2 mimicking Kawasaki disease (Kawa-COVID-19): a multicentre cohort

BACKGROUND

Current data suggest that COVID-19 is less frequent in children, with a milder course. However, over the past weeks, an increase in the number of children presenting to hospitals in the greater Paris region with a phenotype resembling Kawasaki disease (KD) has led to an alert by the French national health authorities.

METHODS

Multicentre compilation of patients with KD in Paris region since April 2020, associated with the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ('Kawa-COVID-19'). A historical cohort of 'classical' KD served as a comparator.

RESULTS

Sixteen patients were included (sex ratio=1, median age 10 years IQR (4·7 to 12.5)). SARS-CoV-2 was detected in 12 cases (69%), while a further three cases had documented recent contact with a quantitative PCR-positive individual (19%). Cardiac involvement included myocarditis in 44% (n=7). Factors prognostic for the development of severe disease (ie, requiring intensive care, n=7) were age over 5 years and ferritinaemia >1400 µg/L. Only five patients (31%) were successfully treated with a single intravenous immunoglobulin (IVIg) infusion, while 10 patients (62%) required a second line of treatment. The Kawa-COVID-19 cohort differed from a comparator group of 'classical' KD by older age at onset 10 vs 2 years (p<0.0001), lower platelet count (188 vs 383 G/L (p<0.0001)), a higher rate of myocarditis 7/16 vs 3/220 (p=0.0001) and resistance to first IVIg treatment 10/16 vs 45/220 (p=0.004).

CONCLUSION

Kawa-COVID-19 likely represents a new systemic inflammatory syndrome temporally associated with SARS-CoV-2 infection in children. Further prospective international studies are necessary to confirm these findings and better understand the pathophysiology of Kawa-COVID-19. Trial registration number NCT02377245.

The association and functional relevance of genetic variation in low-to-medium-affinity Fc-gamma receptors with clinical platelet transfusion refractoriness

BACKGROUND

Inadequate responses to platelet transfusions (i.e., platelet transfusion refractoriness [PLT refractoriness]) are a serious problem. Multiple factors contribute to low yields upon platelet transfusion, among which are platelet-reactive allo-antibodies. Platelet-reactive allo-antibodies occur in up to 30% of patients receiving multiple transfusions, and presumably lead to rapid destruction of the transfused platelets via receptors for IgG, the Fc-gamma receptors (FcγRs). Genetic variation in FcγRs is associated with susceptibility to immune thrombocytopenia, in which autoantibodies against platelets cause thrombocytopenia.

OBJECTIVES

We hypothesized that genetic variation in FcγRs may also influence PLT refractoriness in allo-immunized patients and could help in identifying the patients at risk.

PATIENTS/METHODS

Patients with severe PLT refractoriness for whom diagnostic testing for allo-immunization was requested in the period of 2005 to 2013 were retrospectively included. A case-control study was performed comparing patients in whom platelet-reactive antibodies were detected (n = 181) with ethnically matched healthy controls (n = 180) to determine differences in all known functional copy number variations and single nucleotide polymorphisms in FcγRs.

RESULTS AND CONCLUSIONS

None of the tested FcγR genetic variations seemed associated with the development of severe PLT refractoriness. In contrast to observations in immune thrombocytopenia, genetic variation in FcγRs does not seem to influence the chance to develop PLT refractoriness. Our results do not support determination of FcγR genetic background as a means to identify patients most at risk for PLT refractoriness.

Transient and chronic childhood immune thrombocytopenia are distinctly affected by Fc-γ receptor polymorphisms

In childhood immune thrombocytopenia (ITP), anti-platelet autoantibodies mediate platelet clearance through Fc-γ receptor (FcγR)-bearing phagocytes. In 75% to 90% of patients, the disease has a transient, self-limiting character. Here we characterized how polymorphisms of FcγR genes affect disease susceptibility, response to intravenous immunoglobulin (IVIg) treatment, and long-term recovery from childhood ITP. Genotyping of the FCGR2/3 locus was performed in 180 children with newly diagnosed ITP, 22 children with chronic ITP, and 180 healthy control children by multiplex ligation-dependent probe amplification. Children with newly diagnosed ITP were randomly assigned to a single administration of IVIg or observation, and followed for 1 year (Treatment With or Without IVIg for Kids With ITP [TIKI] trial). We defined transient ITP as a complete recovery (≥100 × 10⁹/L) 3 months after diagnosis, including both self-limiting disease/IVIg responders and chronic ITP as absence of a complete recovery at 12 months. ITP susceptibility, as well as spontaneous recovery and response to IVIg, was associated with the genetic variants FCGR2C*ORF and FCGR2A*27W and the FCGR2B promoter variant 2B.4. These variants were overrepresented in patients with transient (N = 131), but not chronic (N = 43), disease. The presence of FCGR2C*ORF predisposed to transient ITP with an odds ratio of 4.7 (95% confidence interval, 1.9-14.3). Chronic ITP was associated with a deletion of FCGR2C/FCGR3B (copy number region 1) with an odds ratio of 6.2 (95% confidence interval, 1.8-24.7). Taken together, susceptibility to transient and chronic ITP is distinctly affected by polymorphic variants of FCGR2/3 genes. Our data suggest that genotyping of the FCGR2/3 locus may be useful for prognosis and guidance of treatment decisions in newly diagnosed childhood ITP.

A framework for understanding Kawasaki disease pathogenesis

Kawasaki disease (KD) is a common vasculitis of childhood, typically affecting children under the age of five. Despite many aspects of its presentation that bear resemblence to acute infection, no causative infectious agent has been identified despite years of intense scrutiny. Unlike most infections, however, there are significant differences in racial predilection that suggest a strong genetic influence. The inflammatory response in KD specifically targets the coronary arteries, also unusual for an infectious condition. In this review, we discuss recent hypotheses on KD pathogenesis as well as new insights into the innate immune response and mechanisms behind vascular damage. The pathogenesis is complex, however, and remains inadequately understood.

CD32a polymorphism rs1801274 affects the risk of Kawasaki disease

Aim: To analyze the impact of CD32a polymorphism rs1801274 on the occurrence of Kawasaki disease (KD) through the meta-analysis.Methods: The correlation between CD32a polymorphism rs1801274 and the susceptibility to KD was appraised using summarized odds ratios (ORs) with their 95% confidence intervals (95% CIs). Besides, stratification analyses were further implemented on the basis of ethnicity and control source, respectively. Between-study heterogeneity was checked adopting chi-square-based Q test, with p < .05 as significant level. And results from Q test determined which model would be employed for OR calculation, fixed- or random-effects. Sensitivity analysis was accomplished to test the stability of final results. Potential publication bias among included studies was investigated using Begg's funnel plot and Egger's test. If publication bias was significant, its influence on overall estimates would be measured adopting the trim-and-fill method.Results: CD32a polymorphism rs1801274 significantly increased KD risk in total analysis under the comparisons of AA vs. GG, AA + AG vs. GG, AA vs. GG + AG, A vs. G and AG vs. GG (OR = 2.69, 95% CI = 1.39-5.20; OR = 2.00, 95% CI = 1.23-3.26; OR = 1.90, 95% CI = 1.23-2.94; OR = 1.77, 95% CI = 1.34-2.34; OR = 1.53, 95% CI = 1.07-2.19). After stratification analysis by ethnicity, similar tendency was also observed in Caucasian and Asian subgroups under corresponding genetic models. And parallel results were replicated in population-based and other-source subgroups after stratified analysis by control source, under some contrasts.Conclusion: CD32a polymorphism rs1801274 has strong relation to KD onset, and the presence of its A allele could elevate the disease incidence.

Current State of Precision Medicine in Primary Systemic Vasculitides

Precision medicine (PM) is an emerging data-driven health care approach that integrates phenotypic, genomic, epigenetic, and environmental factors unique to an individual. The goal of PM is to facilitate diagnosis, predict effective therapy, and avoid adverse reactions specific for each patient. The forefront of PM is in oncology; nonetheless, it is developing in other fields of medicine, including rheumatology. Recent studies on elucidating the genetic architecture of polygenic and monogenic rheumatological diseases have made PM possible by enabling physicians to customize medical treatment through the incorporation of clinical features and genetic data. For complex inflammatory disorders, the prevailing paradigm is that disease susceptibility is due to additive effects of common reduced-penetrance gene variants and environmental factors. Efforts have been made to calculate cumulative genetic risk score (GRS) and to relate specific susceptibility alleles for use of target therapies. The discovery of rare patients with single-gene high-penetrance mutations informed our understanding of pathways driving systemic inflammation. Here, we review the advances in practicing PM in patients with primary systemic vasculitides (PSVs). We summarize recent genetic studies and discuss current knowledge on the contribution of epigenetic factors and extracellular vesicles (EVs) in disease progression and treatment response. Implementation of PM in PSVs is a developing field that will require analysis of a large cohort of patients to validate data from genomics, transcriptomics, metabolomics, proteomics, and epigenomics studies for accurate disease profiling. This multi-omics approach to study disease pathogeneses should ultimately provide a powerful tool for stratification of patients to receive tailored optimal therapies and for monitoring their disease activity.

Functional Attributes of Antibodies, Effector Cells, and Target Cells Affecting NK Cell-Mediated Antibody-Dependent Cellular Cytotoxicity

Ab-dependent cellular cytotoxicity (ADCC) is one of the most important effector mechanisms of tumor-targeting Abs in current immunotherapies. In ADCC and other Ab-dependent activation of myeloid effector cells, close cell-cell contact (between effector and target cell) and formation of immunological synapses are required. However, we still lack basic knowledge on the principal factors influencing ADCC potential by therapeutic Abs. In this study we investigated the combined roles of five factors affecting human NK cell-mediated ADCC, namely: 1) Ag density, 2) target cell membrane composition, 3) IgG FcγR polymorphism, 4) FcγR-blocking cytophilic Abs, and 5) Ab fucosylation. We demonstrate that the magnitude of NK cell-mediated ADCC responses is predominantly influenced by Ag density and Ab fucosylation. Afucosylation consistently induced efficient ADCC, even at very low Ag density, where fucosylated target Abs did not elicit ADCC. On the side of the effector cell, the FcγRIIIa-Val/Phe158 polymorphism influenced ADCC potency, with NK cells expressing the Val158 variant showing more potent ADCC. In addition, we identified the sialic acid content of the target cell membrane as an important inhibitory factor for ADCC. Furthermore, we found that the presence and glycosylation status of aspecific endogenous Abs bound to NK cell FcγRIIIa (cytophilic Abs) determine the blocking effect on ADCC. These five parameters affect the potency of Abs in vitro and should be further tested as predictors of in vivo capacity.

Genetic Variation in Low-To-Medium-Affinity Fcγ Receptors: Functional Consequences, Disease Associations, and Opportunities for Personalized Medicine

Fc-gamma receptors (FcγR) are the cellular receptors for Immunoglobulin G (IgG). Upon binding of complexed IgG, FcγRs can trigger various cellular immune effector functions, thereby linking the adaptive and innate immune systems. In humans, six classic FcγRs are known: one high-affinity receptor (FcγRI) and five low-to-medium-affinity FcγRs (FcγRIIA, -B and -C, FcγRIIIA and -B). In this review we describe the five genes encoding the low-to-medium -affinity FcγRs (FCGR2A, FCGR2B, FCGR2C, FCGR3A, and FCGR3B), including well-characterized functionally relevant single nucleotide polymorphisms (SNPs), haplotypes as well as copy number variants (CNVs), which occur in distinct copy number regions across the locus. The evolution of the locus is also discussed. Importantly, we recommend a consistent nomenclature of genetic variants in the FCGR2/3 locus. Next, we focus on the relevance of genetic variation in the FCGR2/3 locus in auto-immune and auto-inflammatory diseases, highlighting pathophysiological insights that are informed by genetic association studies. Finally, we illustrate how specific FcγR variants relate to variation in treatment responses and prognosis amongst autoimmune diseases, cancer and transplant immunology, suggesting novel opportunities for personalized medicine.

Expression, Role, and Regulation of Neutrophil Fcγ Receptors

Neutrophils are best known for their critical role in host defense, for which they utilize multiple innate immune mechanisms, including microbe-associated pattern recognition, phagocytosis, production of reactive oxygen species, and the release of potent proteases, mediators, antimicrobials, and neutrophil extracellular traps. Beyond their well-established contribution to innate immunity, neutrophils were more recently reported to interact with various other cell types, including cells from the adaptive immune system, thereby enabling neutrophils to tune the overall immune response of the host. Neutrophils express different receptors for IgG antibodies (Fcγ receptors), which facilitate the engulfment of IgG-opsonized microbes and trigger cell activation upon cross-linking of several receptors. Indeed, FcγRs (via IgG antibodies) confer neutrophils with a key feature of the adaptive immunity: an antigen-specific cell response. This review summarizes the expression and function of FcγRs on human neutrophils in health and disease and how they are affected by polymorphisms in the FCGR loci. Additionally, we will discuss the role of neutrophils in providing help to marginal zone B cells for the production of antibodies, which in turn may trigger neutrophil effector functions when engaging FcγRs.