FcgammaRIIa Polymorphism Research Articles

Intravenous Immunoglobulin (IVIg) Is a Highly Effective Treatment for HIT: Critical Role of the IgG Fc Domain in Inhibiting HIT Antibody-Mediated Platelet Activation

Heparin-induced thrombocytopenia (HIT) is characterized by antibodies (abs) directed to complexes of PF4 and heparin that are an important cause of morbidity and mortality in heparin-treated patients. Direct Thrombin inhibitors (DTIs) and fondaparinux (off-label) are the mainstays of therapy, but despite their use, thrombosis is common. Thus there is a need for additional treatment regimens, especially in severely affected patients. We recently encountered two patients with severe thrombotic HIT and persistent thrombocytopenia who responded dramatically to intravenous immunoglobulin G (IVIg) and performed studies to examine the basis for this effect.Patient 1, a 47-year-old man, presented with severe thrombocytopenia (TP, 13,000/ul), lower extremity thromboses and pulmonary embolism 13 days after being treated with heparin during cardiac surgery. PF4 ELISA (2.7 OD) and serotonin release assay (SRA) (100%) were strongly positive. Argatroban and then bivalirudin were given, but TP persisted for 17 days (Fig 1A). On Days 18 and 19 1gm/Kg of IVIg was administered. Platelet counts rose dramatically and he was discharged four days later (Fig 1A). Surprisingly, despite platelet recovery, two "platelet-activating" HIT tests, the SRA and newly described PEA (Padmanabhan et al, Chest 2016, epub) remained strongly positive (data not shown). The standard PEA is performed using platelets "primed" by pre-incubation with 30 ug/ml platelet factor 4 (PF4) and no heparin. However strong platelet-activating HIT abs, like those seen in this patient with "delayed HIT" may require only a small amount of PF4 to prime platelets for activation. When testing was repeated using platelets primed with only 1 ug/ml PF4 (Low PF4 PEA, LP-PEA), an inverse correlation between the PEA signal and platelet counts was observed (Fig 1A).Patient 2, a 73-year-old man, presented with severe TP (25,000/ul) and pulmonary embolism 9 days after receiving heparin during cardiac surgery. PF4 ELISA (2.3 OD) and SRA (100%) were strongly positive. He was treated with bivalirudin but remained thrombocytopenic with positive HIT test results (not shown) for 3 weeks (Fig 1B). Therapeutic plasma exchange (TPE) was performed on Day 22 with no effect on platelet counts. On Days 23 and 24, 1gm/Kg of IVIg was administered. Platelet counts rose sharply and he was discharged one week later. As with Patient 1, the LP-PEA but not the PEA test results became negative after IVIg treatment, coinciding with improvement in platelet counts (Fig 1B).To understand the beneficial effect of IVIg in these patients, we added IVIg to patient serum in amounts sufficient to produce IgG levels comparable to those achieved in vivo and examined the effects in the PEA/LP-PEA assay. At the 2gm/Kg dose, IVIg reduced the LP-PEA signal significantly in both patients (Fig 1C). Similar results were obtained with sera from 5 other patients with HIT, indicating that the IVIg effect is not restricted to HIT sera with unique characteristics (Fig 1D). Purified IgG Fc fragments are both necessary and sufficient to achieve this effect, while Fab fragments demonstrated no inhibitory activity (Fig 1E).IgG2 comprises approximately 25% of IVIg and it is known that IgG2 binds poorly to the RR131 isotype of the platelet Fc receptor, FcGammaRIIa. Thus, RR131 platelets should be less susceptible to IVIg-based inhibition than HH131 platelets. Consistent with this, activation was more effectively inhibited with HH131 platelets than with RR131 (Fig 1F). These results were confirmed using a second HIT ab (data not shown).Experience with these patients shows that IVIg can be highly effective for treating patients with HIT unresponsive to standard therapies. The constant domain (Fc) of IgG plays a critical role in mediating this effect. Patients homozygous for the RR131 FcGammaRIIa polymorphism may be less responsive to IVIg treatment and may require higher doses or more prolonged therapy. IVIg has been used only rarely to treat HIT. Additional studies are needed to define its role in treating this dangerous condition. [Display omitted] DisclosuresPadmanabhan:Bloodcenter of Wisconsin: Patents & Royalties: A patent application has been filed on a Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591; Fenwal (Fresenius Kabi): Research Funding; Schlesinger & Associates: Consultancy, Honoraria; LEK Consulting: Consultancy, Honoraria; Mallinckrodt Pharmaceuticals: Consultancy, Honoraria; Terumo BCT: Consultancy, Honoraria. Jones:Bloodcenter of Wisconsin: Patents & Royalties: A patent application has been filed on a Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591. Bougie:Bloodcenter of Wisconsin: Patents & Royalties: A patent application has been filed on a Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591. Aster:Bloodcenter of Wisconsin: Patents & Royalties: A patent application has been filed on a Method of detecting platelet activating antibodies that cause heparin-induced thrombocytopenia/thrombosis; PCT/US14/62591.

FcgammaRIIA and FcgammaRIIIB polymorphisms in Brazilian systemic lupus erythematosus and associations with clinical manifestations

FcgammaRIIA and FcgammaRIIIB polymorphisms in Brazilian systemic lupus erythematosus and associations with clinical manifestations

Correlation of Fc Gamma RIIA Polymorphisms with EBV-Positivity and LMP1 Expression in Patients with Low Grade B-Cell Lymphomas

Abstract 1600 Background:It is well known that Fc gamma receptors expressed on monocytes and macrophages enhance the presentation of antibody-bound antigens. Human Fc gamma receptors are coded by genes located on chromosome 1q23. Fc gamma RIIA (CD32) is a transmembrane protein expressed on neutrophils. Efficacy of phagocytosis by polymorphonuclear neutrophils is known to vary between allotypes of Fc gamma RIIa. Polymorphisms of Fc gamma RIIA have been linked to susceptibility to infections by encapsulated bacteria (N. meningitides, H. influenzae) and severe sepsis by several authors. Moreover, susceptibility to perinatal HIV-1 infection has been attributed to polymorphisms of Fc gamma RIIA, and this is the only association of FC gamma RIIA with viral diseases in the literature. FcγRIIA gene has two condominantly expressed alleles the 131-Arg (R131) and the 131-His (H131) allele. R131 binds IgG2 much less avidly than H131. Aim of the study:To propose Fc gamma RIIA polymorphisms as a genetic risk factor for acquisition and latency of EBV infection in patients with lymphoproliferative diseases. Patients and Methods:Forty Greek patients with EBV-unrelated low grade B-cell leukemic lymphomas (chronic lymphocytic leukemia: 23, marginal zone lymphoma: 11, mantle cell lymphoma: 3, hairy cell leukemia: 2, follicular lymphoma: 1), were included in the study. Patients' sera were tested with ELISA for the presence of EBV-VCA IgG antibodies. DNA from peripheral blood was studied by quantitative real time - PCR for the EBV-R gene, while RNA from peripheral blood was studied by RT-PCR for the EBV-LMP1 oncoprotein. Genomic DNA from peripheral blood was tested for Fc gamma RIIA 131Histidin(H)/arginine(R) SNP, by PCR, followed by restriction fragment length polymprphim (RFLP) using the appropriate enzyme (BstUI, Fermentas, Vilnius, Lithuania). We used Pearson Chi-square for the statistical analysis of the results. Results:All but 2 patients were positive for EBV-VCA IgG antibodies. Nineteen patients (47.5%) were EBV-positive. LMP1 was expressed in 13/19 (68.4%) EBV-positive patients. The vast majority (16/19, 84.2%) of EBV positive patients carried the R131 allele (13 were heterozygous and 3 homozygous), while only 3 were homozygous for the H131 allele. Among 21 EBV-negative patients, only 6 (28.5%) carried the R131 allele (4 heterozygous and 2 homozygous) (2-sided p=0001). R131 allele was present in 11/13 (84.6%) LMP1-positive patients in comparison to 6/21 (28.0%) EBV-negative patients (2-sided p=0.002). Discussion:The high prevalence of FC gamma RIIA polymorphisms among EBV-positive patients indicates a possible pathogenetic role of the FC gamma RIIA in acquisition and chronicity of EBV infection. LMP1 is the major oncoprotein of EBV. The correlation of this polymorphism to LMP1 expression is an indication that it may play a major role in the expression of latency phase proteins, a fact that may further be implicated in the pathogenesis of lymphoproliferative diseases in these patients. We continue the study in our centre, increasing the number of patients enrolled. Disclosures:No relevant conflicts of interest to declare.

Interleukin-15 enhances rituximab-dependent cytotoxicity against chronic lymphocytic leukemia cells and overcomes transforming growth factor beta-mediated immunosuppression

Chemoimmunotherapy with anti-CD20 monoclonal antibody rituximab is increasingly used for the treatment of patients with chronic lymphocytic leukemia (CLL). Antibody-dependent cytotoxicity (ADCC) is one of the most important mechanisms of action of rituximab against B-cell malignancies. We studied ways to increase the cytotoxic effect of rituximab on CLL cells by enhancing ADCC. Peripheral blood mononuclear cell (PBMC) or purified natural killer (NK) cells from healthy donors were activated with interleukin-15 (IL-15) and cultured with rituximab-coated CLL cells, and ADCC was evaluated using a (51)chromium release assay. The IL-15 significantly enhanced invitro ADCC against CLL cells, and this effect was mainly mediated by NK cells. The IL-15 treated effector cells with the low affinity FcγRIIIA receptor (158FF) had an ADCC comparable to those with the high affinity FcγRIIIA form (158VF). Inaddition, IL-15 enhanced rituximab-mediated ADCC of CLL cells in the presence of transforming growth factor-beta. The IL-15 increases rituximab-mediated ADCC against CLL, and supports the use of such agents with the goal of improving clinical response to chemoimmunotherapy in patients with CLL.

FCgammaRIIa Polymorphism Is Not Associated with Overall Response, Progression Free Survival and Overall Survival In Diffuse Large B-Cell Lymphoma Treated with Rituximab

AbstractAbstract 5078 Background:Low-affinity receptor for the Fcγ region of immunoglobulin G (IgG) (FcγR) is constitutively expressed on resting human neutrophils. These receptor, termed FcγRIIa display biallelic polymorphism which have functional consequences with respect to binding and/or ingestion of targets opsonized by human IgG subclass antibodies. Rituximab is a chimeric monoclonal antibody directed against CD20, an antigen found in most B-cell malignancies. Multiple mechanisms have been proposed for the activity of Rituximab, including antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC) and a direct proapoptotic effect. F(ab′)2 Rituximab homodimers were shown to be effective in inducing apoptosis of B-cell lymphoma cell lines in vitro. Recently, it have been established that ADCC is important as predominant mechanism of lymphoma cell clearance and that Fcγ receptors (FcγRs) are critical for the in vivo actions of Rituximab in non-Hodgkin lymphoma (NHL). A genomic polymorphism at amino acid 131 of FcγRIIA has been described whereby the presence of Histidine (H) rather than Arginine is associated with responses to the CD20-directed immunoglobulin G1 (IgG1) Rituximab among patients with indolent lymphoma. FcγRIIA genotype have been associated with a better clinical and molecular response in follicular lymphoma patients treated as first line therapy with Rituximab alone and in patients with diffuse large B-cell lymphoma (DLBCL) treated with the concomitant administration of Rituximab and CHOP (R-CHOP). Methods:Here we analyzed the role of specific polymorphism of activating FcγRIIA in 64 patients with DLBCL treated with R-CHOP concerning prediction complete response (CR), Progression Free Survival (PFS) and Overall Survival (OS) using a polymerase chain reaction-restriction fragment length polymorphism method. Results:The median age of the patients was 48.6 years. Out of the 64 patients (32%), were stage III-IV and 27 (42.5%) had more than 2 factors of the International Prognostic Index. Fity-six (89%) had CR and 7 (9.5%) had refractory disease (RD). Seven (11%) of the patients presented relapses. Deaths occurred in 6 (9.3%) patients with follow up of 19,5 months (range 21,3-50,1). The distribution of FcγRIIA polymorphism genotypes was: 15 (23,4%) HH, 30(46,9%) HR and 19(29,7%) RR, while considering only two groups (HH and R allele (HR and RR) was 15 (23,4%) and 49 (76,6%). There were no statistically significant differences in the genotypes groups according prognostic factors. In addition, there were not differences between response rate and FcγRIIA genotypes polymorphism: the CR in HH and HR/ RR were respectively 80% and 89%, p=0,377. It was not found differences regarding FcγRIIa. HH genotype presented a median PFS and OS. Thus, PFS HH genotype presented a median PFS 20,96 ± 10,49 months versus HR/RR median PFS 12,03 ± 7,71 months, p = 0,765, and OS 23,26 ± 10,42 months versus HR/ RR median OS 12,7 ± 7,42 months, p =0,98. Conclusions:Contrary to recent report we showed that FcγRIIA polymorphism is not associated to overall response, PFS and OS in patients with DLBCL treated with R-CHOP. Disclosures:No relevant conflicts of interest to declare.

Vaccine-induced IgG2 anti-HIV p24 is associated with control of HIV in patients with a ‘high-affinity’ FcγRIIa genotype

We have previously shown that vaccination with a recombinant fowlpox virus carrying the genes for HIV Gag-Pol and interferon-gamma (IFN-gamma) was associated with partial control of HIV replication after antiretroviral therapy (ART) was ceased but not with increased anti-HIV T-cell responses. Because IFN-gamma enhances IgG2 production, and IgG2 antibodies to HIV antigens and the 'high-affinity' polymorphism of FcgammaRIIa (the major Fc receptor for IgG2) have been associated with a favourable outcome of HIV infection, we examined the association of IgG2 antibodies to HIV p24 and 'high-affinity' polymorphisms of FcgammaRIIa with control of HIV replication in these patients. Plasma from weeks 0 (cessation of ART 1 week after the last vaccination), 9 and 20 was available from patients who had received the full construct vaccine, a partial construct (without IFN-gamma) or placebo. IgG2 and IgG1 anti-p24 and anti-gp41 were assayed and all patients were genotyped for the FcgammaRIIa 131 R/H polymorphism that affects IgG2 binding. At week 0, IgG2 anti-p24 was present in five of nine full construct patients but none of 14 partial construct or placebo patients and was associated with a smaller increase in plasma HIV RNA over 20 weeks. Patients with IgG2 anti-p24 and the 'high-affinity' polymorphism of FcgammaRIIa exhibited lower HIV replication than other patients at week 20. The role of IgG2 anti-HIV antibodies and FcgammaRIIa in the control of HIV replication should be investigated further. Inclusion of an IFN-gamma gene in DNA vaccine constructs might be a means of enhancing IgG2 antibody production.

An Update on the Prevalence and Characterization of H-PF4 Antibodies in Asian-Indian Patients

Heparin is the second most widely used anticoagulant/antithrombotic agent besides warfarin and is commonly used for various purposes such as treatment and surgical indications. A significant adverse effect of heparin treatment can occur when heparin binds platelet factor 4 (H-PF4) to form a complex that results in formation of H-PF4 antibodies, which in turn leads to platelet/endothelial cell activation followed by heparin-induced thrombocytopenia (HIT). Based on the heparin-induced platelet aggregation and enzyme-linked immunosorbent assay tests, the H-PF4 antibody (HIT antibody) was diagnosed in 6% of Indian patients undergoing cardiovascular surgery who received unfractionated heparin, but the frequency of occurrence rose to 15% when the patients were tested with the (14)C-serotonin release assay. This highlights some methodological variations in the diagnosis of HIT antibodies. It was also found that all the HIT-positive patients were either homozygous or heterozygous for the FcgammaRIIa polymorphism, which also highlights the role of this polymorphism in the occurrence of HIT. Very recent studies show that increases in HIT antibody production may also be due to heparin contaminants. Although these antibodies do not result in thrombocytopenia, contaminants in heparin may be capable of triggering a differential immunogenic response in comparison with contaminant-free heparin. Here we discuss the methodological differences in diagnosing HIT, the potential impact of contaminants in heparin, as well as future considerations.

Pharmacokinetic study and Fcγ receptor gene analysis in two patients with rheumatoid arthritis controlled by low-dose infliximab

The main aim of this study is to investigate the pharmacokinetics of infliximab and Fcgamma receptor (FcgammaR) polymorphism in two patients with rheumatoid arthritis (RA) who were well controlled by low-dose infliximab. A 57-year-old woman (Patient 1) and a 67-year-old woman (Patient 2) had active RA despite methotrexate and prednisolone treatments. They improved after the addition of infliximab (3 mg/kg), but developed pneumonia and sepsis, respectively. Although the infliximab doses were reduced to 1.5 mg/kg and 1 mg/kg, respectively, clinical improvements were maintained. Blood samples were obtained at 1 h after infliximab administration and at eight weeks (just before the next dose). The elimination half-life was determined by the serum concentration of infliximab. We also analyzed the polymorphisms of FcgammaRIIA, FcgammaRIIIA, and FcgammaRIIIB for the genomic DNA samples from the two patients and three controls. Amplification of the FcgammaR-genomic regions in allotype-specific polymerase chain reactions was used to distinguish the genotypes. Decresed clearance of infliximab was proven by a pharmacokinetic study of these patients under low-dose infliximab therapy. 131H/H (FcgammaRIIA) and 176F/F (FcgammaRIIIA) were detected in both patients. NA1/NA2 and NA2/NA2 (FcgammaRIIIB) were detected in Patients 1 and 2, respectively. These patients were well controlled over the long term by low-dose infliximab. The mechanism of the reduced clearance of infliximab might possibly be explained in part by the FcgammaR polymorphisms.

FcgammaRIIIa polymorphisms and cetuximab induced cytotoxicity in squamous cell carcinoma of the head and neck.

The interaction of Fc fragments of antibodies with the Fcgamma receptors is an essential checkpoint in antibody-dependent cellular cytotoxicity (ADCC). Specific polymorphisms at position 158 enhance FcgammaRIIIa affinity for IgG1 and are associated with improved clinical outcome in lymphoma patients treated with IgG1 anti-CD20 antibody. The role of ADCC in the therapeutic effects of the alpha-epidermal growth factor receptor (EGFR) mAb, cetuximab, in patients with squamous cell carcinoma of the head and neck (SCCHN) is poorly defined. We employed three SCCHN cell lines to test two hypotheses: (1) SCCHN is susceptible to cetuximab-mediated ADCC, (2) efficacy of ADCC is associated with polymorphisms at position 158 of FcgammaRIIIa. FcgammaRIIIa-158 polymorphisms were determined for healthy donors, and their purified NK cells were used as effector cells against three SCCHN cell lines in ADCC assays. Cytotoxicity levels were compared for each polymorphism class. Proliferation and cell cycle assays were done to examine the direct effects of cetuximab. Our results indicate that SCCHN is susceptible to cetuximab-mediated ADCC in vitro. NK cytotoxic efficiency correlates with donor 158-polymorphisms in FcgammaRIIIa. Overall cytotoxicity was greatest for individuals having a single V allele when compared to homozygous F/F individuals; the cumulative percent cytotoxicity for each polymorphism among the cell lines was 58.2% V/V, 50.6% V/F, and 26.1% F/F (P < 0.001). Additionally, the presence of a V allele correlated with superior natural cytotoxicity against NK sensitive targets. These data have both prognostic and therapeutic relevance and support the design of a prospective trial to determine the influence of FcgammaRIIIa polymorphisms on the clinical outcome of patients with SCCHN treated with alpha-EGFR mAbs.

FCgamma Receptor Polymorphisms Do Not Influence the Outcome of Treatment with Rituximab Followed by Active Immunotherapy with Mitumprotimut-T (FavId®, Id-KLH).

Background: Patient specific active idiotype immunotherapy with immunoglobulin idiotype is a promising new therapy for follicular NHL. Response to therapy may include both humoral and cellular anti-idiotypic immunity, but it is not clear which is most important. Prior studies have suggested that immunoglobulin FCgammaRIIIa (FCgRIIIa) polymorphisms at position 158 valine (V) or phenylalanine (F) effect the response to treatment with rituximab as well as outcomes from idiotype immunotherapy following objective response to chemotherapy. Here we present data assessing the correlation of FCgRIIIa polymorphisms and outcomes from idiotype immunotherapy following treatment with rituximab.Treatment: We determined the FCgRIIIa genotype using a SSCP method with genomic DNA isolated from 55 rituximab-naïve patients treated on a Phase II trial of mitumprotimut-T (FavId®, Id-KLH) (Koc et al, Blood , 2006; 108: #691). Four patients who progressed following rituximab and therefore did not receive mitumprotimut-T were excluded from this analysis. All 55 patients in this analysis had follicular NHL with a median age of 55 years. Thirty five patients were treatment naïve and 20 had relapsed following prior chemotherapy. Patients received rituximab (375mg/m2 i.v. weekly x 4) and those with stable or responding disease assessed at Week 11 received Id-KLH (1 mg s.q. monthly x 6) starting on Week 12 along with Leukine® (sargramostim, GM-CSF, 250 mcg, s.q.) on Days 1–4. Pts continued to receive booster injections on a reduced schedule, every other month x6 then quarterly thereafter, until disease progression. Radiological scans were performed every 3 months for the first 2 years of follow up, then every 6 months thereafter and reviewed centrally. Objective response and time to tumor progression (TTP) were assessed using modified IWG criteria (Cheson et al, J Clin Oncol 1999; 17:1244). Response at 3 months, best response, TTP and progression free survival (PFS) at 1 year and 3.5 years were all assessed with respect to FCgRIIIa genotypes.Results: DNA was isolated from all 55 patients and successfully analyzed by SSCP for polymorphisms at position 158 of FCgRIIIa. Nine of 55 patients were V/V (16%), 27 were F/F (49%) and 19 were heterozygous V/F (35%). Overall, the 3 month response rate CR+PR) was 31/55 (56%) and the best overall response rate was 39/55 (71%). The 3 month response (post rituximab) was 5/9 (56%) for V/V, 9/19 (47%) for V/F and 17/27 (63%) for F/F patients. Best response was 6/9 (67%) for V/V, 12/19 (63%) for V/F and 21/27 (78%) for F/F patients. Median TTP was 19.5 months for V/V, 22.3 months for V/F and 18 months for F/F patients. The PFS at 1 year post initiation of rituximab was 57% for V/V, 61% for VF and 68% for FF patients while at the median follow-up of 3.5 years the PFS was 31% for V/V, 42% for V/F and 31% for F/F patients.Conclusions: FCgRIIIa polymorphisms were not associated with response rate or time to progression following a treatment program consisting of single agent rituximab followed by idiotype vaccination with mitumprotimut-T in rituximab-naïve patients. Results from an ongoing randomized Phase III study will assess the efficacy of this combined therapy, but these data suggest that long term PFS in patients receiving an idiotype vaccine following rituximab may rely more on a cell mediated immune response rather than a humoral response to idiotype.

6015 POSTER FcgammaRIIIa and FcgammaRIIa polymorphisms do not influence overall survival in follicular lymphoma patients treated with rituximab

6015 POSTER FcgammaRIIIa and FcgammaRIIa polymorphisms do not influence overall survival in follicular lymphoma patients treated with rituximab

Relevance of the low-affinity type of the Fcγ-receptor IIIa-polymorphism in bullous pemphigoid

Bullous pemphigoid (BP) is mediated by autoantibodies directed against molecules of the basement membrane zone. The biological function of antibodies involves binding to Fc-receptors expressed on human leucocytes. Recent studies suggested that a functional single-nucleotide-polymorphism of the Fcgamma-receptor IIIa (FcgammaRIIIa = CD16) at nucleotide 559 might predispose to the development of antibody-associated autoimmune disorders. This allelic difference affects the level of receptor affinity by predicting either a phenylalanine (F 158, low-affinity) or valine (V 158, high-affinity). We investigated if inherited frequencies of the high- and low-affinity FcgammaRIIIa polymorphism differed between patients with BP and healthy subjects. Genomic DNA from peripheral white blood cells was analyzed regarding FcgammaRIIIa polymorphism at nucleotide 559 by an established polymerase chain reaction. Sixty-seven Caucasian patients with BP and 88 healthy controls were included into the study. There was no significant difference in the distribution of the homozygous high-affinity FcgammaRIIIa-allotype (V/V) between BP-patients (14.9%) and healthy control subjects (20.5%). In contrast, 58.2% of the BP-patients were homozygous for the low-affinity FcgammaRIIIa-allotype (F/F), compared to 28.4% of the healthy controls (P = 0.001, OR 3.51). The frequencies of the polymorphism in the control group were in range of formerly published frequencies for healthy Caucasian subjects. Thus, the FcgammaRIIIa (158 F/V) polymorphism may modulate the susceptibility to acquire BP.

Fc gamma RIIa, IIIa and IIIb polymorphisms in Turkish children susceptible to recurrent infectious diseases

The efficacy of IgG-induced Fc gamma receptor (FcgammaR) function displays interindividual heterogeneity due to genetic polymorphisms of three FcgammaR subclasses: FcgammaRIIa, FcgammaRIIIa and FcgammaRIIIb. FcgammaR polymorphisms may contribute to disease susceptibility or may alter disease course. The aim of this study is to examine FcgammaR gene polymorphisms in Turkish children with recurrent respiratory tract infections and without well known humoral immunodeficiencies. For the patients in the study group (n=52), recurrent infection was defined as the presence of at least six infection episodes a year. Seventy-one healthy children with a maximum of two infections in a year were enrolled as the control group. Subjects in both groups had no abnormalities in serum immunoglobulins, IgG subsets and specific antibody levels. For FcgammaRIIa: H131H, H131R, R131R genotypes and 131R, 131H alleles; for FcgammaRIIIa: F158F, F158V, V158V genotypes and 158F, 158V alleles; and for FcgammaRIIIb: -NA1/NA1, NA1/NA2, NA2/NA2 genotypes and NA1, NA2 alleles were determined by using amplification refractory mutation system polymerase chain reaction (ARMS-PCR). Compared with the control group, the FcgammaRIIa-R131R genotype and 131R allele were found to be significantly elevated in the study group, and FcgammaRIIa-H131H genotype and 131H allele in the study group were significantly lower than in the control group. Genotypes and alleles related with FcgammaRIIIa and FcgammaRIIIb gene polymorphisms did not show any significant difference between the study and control groups. FcgammaRIIa gene polymorphism (R131R) may increase the risk and susceptibility for recurrent infectious diseases in children.

FcγRIIa-131R allele and FcγRIIIa-176V/V genotype are risk factors for progression of IgA nephropathy

Fcgamma receptors (FcgammaRs) may play an important role in positive and negative regulation of immune cell responses and immune complex (IC) clearance. Mesangial IgG deposition and circulating IgG/IgA-IC in sera are observed in patients with IgA nephropathy (IgAN). Therefore, the pathological roles of IgG-IC in IgAN have been discussed. On the other hand, several studies have identified FcgammaR polymorphisms (FcgammaRIIa, FcgammaRIIIa and FcgammaRIIIb) that determine susceptibility to autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. The objective of the present study was to clarify whether FcgammaR polymorphisms influence susceptibility to IgAN, clinical features or severity in patients with IgAN. Japanese patients with IgAN (n = 124) and healthy controls (n = 100) were genotyped for FcgammaR polymorphisms (FcgammaRIIa-131H or R, FcgammaRIIIa-176F or V and FcgammaRIIIb-NA1 or -NA2). The genotyping of these polymorphisms was performed using allele-specific polymerase chain reaction (PCR) methods. Associations among FcgammaR polymorphisms and susceptibility, age of onset, levels of serum immunoglobulins, intensity of glomerular IgG deposition and pathological severity were analysed. These three FcgammaR polymorphisms showed no significant differences in genotype and allele frequencies between the IgAN patients and healthy controls. Each FcgammaR polymorphism had no influence on age of onset, serum levels of IgG and glomerular IgG deposition in IgAN. However, FcgammaRIIa-131R (R/R or H/R) or FcgammaRIIIa-176V homozygous carriers (V/V) showed significantly more severe injury than FcgammaRIIa-131H homozygous (H/H) (P < 0.03) or FcgammaRIIIa-176F carriers (F/F or F/V) (P < 0.03), respectively. The present study shows that polymorphisms of FcgammaRIIa and FcgammaRIIIa influence the severity of IgAN in Japanese patients but not the incidence, suggesting that IgG-IC may play important roles in the progression and prognosis of this disease via FcgammaRs.

Polymorphism of Fcγ RIIa May Affect the Efficacy of γ-Globulin Therapy in Kawasaki Disease

We evaluated whether there is a possible relationship between the effectiveness of gamma-globulin treatment for patients with Kawasaki disease (KD) and the polymorphism of Fcgamma RIIa, IIIb, and IIIa. Genomic DNA was extracted from whole blood collected from 56 patients with KD who received gamma-globulin treatment. The genotypes for Fcgamma RIIIb-NA(1, 2), Fcgamma RIIa-H/R131, and FcgammaRIIIa-F/V158 were determined to investigate the association between these polymorphisms and the development of coronary lesions (CALs). Twenty-three percent of patients with the HH allele for the Fcgamma RIIa polymorphism progressed to CALs, compared with 60% with the HR and RR alleles. HR and RR alleles may be a predictor of the progression of CALs in KD before the initiation of gamma-globulin therapy.

Heterogeneity of platelet responsiveness to anti‐CD36 in plasma associated with adverse transfusion reactions

Antibodies to CD36 (anti-CD36) are clinically important. As some platelet immunoglobulins produced by transfusion or pregnancy have been shown to induce platelet activation and to play roles in non-haemolytic transfusion reactions (NHTRs), we investigated the in vitro response of platelets to plasma containing anti-CD36. Plasma containing anti-CD36, implicated in the development of NHTRs and subsequent thrombocytopenia, was incubated with CD36-positive platelets. Plasma-induced platelet activation was examined by evaluating platelet aggregation and RANTES (regulated on activation, normal, T-cell expressed, and presumably secreted) release. Platelet activation was induced by plasma alone in four out of 20 CD36-positive subjects. In seven subjects, platelet activation was synergistically induced by the combination of epinephrine priming and the plasma. The platelets of the nine remaining subjects failed to respond to the plasma. Platelet activation induced by either the plasma alone or by synergy with epinephrine required the involvement of Fc gamma RIIa. The different responsiveness of the platelets was partially associated with the surface levels of CD36 and Fc gamma RIIa, but not with Fc gamma RIIa polymorphisms. Plasma containing anti-CD36, implicated in the development of NHTRs, exhibited a platelet-activating capability. Additionally, platelets from healthy human subjects exhibited a considerable degree of heterogeneity in their responsiveness to this plasma. The heterogeneity of these responses may determine the occurrence of anti-CD36-related NHTRs.

Prevalence of heparin-induced antibodies in patients with chronic renal failure undergoing hemodialysis

Heparin-induced thrombocytopenia (HIT) type II is a serious complication of heparin therapy. It presents initially as thrombocytopenia, and is associated with thrombosis in 20-50% of the cases. HIT is related to the presence of heparin-induced antibodies (HIA), which show specificity for the PF4-heparin (PF4-H) complex. The FcgammaRIIa receptor has been suggested to participate in the pathogenic mechanism of HIA. Since patients undergoing chronic hemodialysis (HD) are exposed repeatedly to heparin, we studied the prevalence of HIA and their eventual relationship with thrombocytopenia and/or thrombosis, and the possible participation of the FcgammaRIIa polymorphism. We studied 207 patients with chronic renal failure (CRF) undergoing HD. As a control we included 130 blood donors and 28 patients with CRF without HD. The HIA patients were studied with the use of a PF4-H ELISA. Additionally, in some positive cases for the previous test, a 14C- serotonin release assay (14C-SRA) was performed. The polymorphism FcgammaRIIa H/R131 was studied by polymerase chain reaction (PCR) with allele-specific primers. Thirty-seven patients (17.9%) undergoing HD presented with HIA. The majority of these antibodies were IgG, IgM, and IgA. The HIA investigated presented specificity against the PF4-H complex, but not against PF4 alone (P<0.001). Twelve out of 22 (54.5%) PF4-H antibodies were positive when tested with the 14C-SRA. The distribution of the FcgammaRIIa polymorphism in patients and healthy controls was 42.6% and 41.6% for H/H131, 41% and 48.9% for the H/R131 isoform, and 16.4% and 9.5% for the R/R131 isoform, respectively. No statistically significant difference in the FcgammaRIIa isoform distribution was found. Twenty-nine out of 156 patients (18.5%) presented thrombocytopenia, and 21/207 (12.4%) had thrombosis of the native vein arterio-venous fistula (AVF). We did not find any statistically significant between HIA and thrombocytopenia or thrombosis. An important proportion of patients with CRF undergoing HD developed HIA, but these cases were not associated with thrombocytopenia or thrombosis of AVF. The frequency of the FcgammaRIIa polymorphism did not statistically differ between HIT type II and normal controls.

Association of Fc gamma receptor IIA polymorphisms with acute renal-allograft rejection.

Acute rejection is a leading cause of early renal-allograft failure. The human Fc gamma receptor IIA (FcgammaRIIA) forms an essential link between the humoral branch and the effector cells of the immune system. In this study, we examined FcgammaRIIA genotypes in renal-allograft recipients (rejectors) with acute graft rejection and in a number of control groups to investigate a possible association between FcgammaRIIA polymorphism and acute renal-allograft rejection. The distribution of the genotypes in the study patient group differed from the control groups. The frequency of homozygosity for FcagammaRIIA-R/R131 in the rejectors was significantly higher than that in the recipients (nonrejectors) with well-functioning renal allografts and in blood donors (P< 0.05). In comparison with the control groups, the rejectors displayed a higher R131 allele frequency (P< 0.05) and a lower H131 allele frequency (P< 0.05). These results reveal a significant association between FcgammaRIIA-R/R131 and acute renal-graft rejection, and it is likely that FcgammaRIIA polymorphisms could be useful markers for potential risk of rejection.

Polymorphism of Fc receptor IIa for immunoglobulin G is associated with placental malaria in HIV-1-positive women in western Kenya.

Genetic polymorphism of the Fc receptor IIa for immunoglobulin (Ig) G (Fc gamma RIIa) determines IgG subclass binding. Previous studies have shown that individuals with the IgG1/3-binding Fc gamma RIIa-Arg/Arg131 genotype are relatively protected against high-density malaria, whereas individuals with the IgG2-binding Fc gamma RIIa-His/His131 genotype are at increased risk for developing cerebral malaria. The present study was undertaken to examine the relationship between Fc gamma RIIa polymorphism and placental malaria (PM) in pregnant women of known human immunodeficiency virus (HIV)-1 status. Fc gamma RIIa genotype was determined in 903 pregnant women who had participated in a study designed to assess the effect that PM has on vertical transmission of HIV-1. Fc gamma RIIa polymorphism was assessed in relation to PM. Among HIV-negative women, there was no difference in the distribution of the Fc gamma RIIa polymorphism by PM status. However, among HIV-positive women, the frequency of the Fc gamma RIIa-His/His131 genotype was significantly higher in women with PM than in women without PM (31% vs. 22%, respectively [P=.032]). In multivariate analysis, the adjusted odds ratio for PM in HIV-positive women with the Fc gamma RIIa-His/His131 genotype versus women in the Fc gamma RIIa-His/Arg131 reference group was 1.72 (95% confidence interval, 1.11-2.69 [P=.016]). The present study suggests that the IgG2-binding Fc gamma RIIa-His/His131 genotype is associated with enhanced susceptibility to PM in HIV-positive women but not in HIV-negative women.

Polymorphism of Fc receptor IIa for IgG in infants is associated with susceptibility to perinatal HIV-1 infection.

To evaluate the effect of polymorphism of the Fc gamma receptor IIa, which is associated with differential human IgG subclass binding, on perinatal HIV-1 transmission. Fc gamma RIIa genotype was tested in 448 HIV-seropositive mothers and their infants from a cohort study designed to assess the effect of placental malaria on HIV vertical transmission conducted from 1996 to 2001 in western Kenya. Fc gamma RIIa polymorphism was analyzed for associations with susceptibility to perinatal HIV infection and all-cause child mortality in HIV-positive children. Overall, 20% of infants were perinatally infected with HIV. There was no statistically significant association between maternal genotype and perinatal HIV-1 transmission. However, frequency of the infant Fc gamma RIIa His/His131 genotype was higher in HIV-positive compared with HIV-negative infants (35% and 21%, respectively), whereas the distribution was reversed (15% and 28%, respectively) for infants with the Fc gamma RIIa Arg/Arg131 genotype. Multivariate logistic regression controlling for maternal and infant confounding factors demonstrated that the odds of perinatal HIV infection in infants with the Fc gamma RIIa His/His131 versus Fc gamma RIIa His/Arg131 genotypes were significantly higher (adjusted odds ratio, 2.22; 95% confidence interval, 1.23-4.02; P = 0.009). There was no evidence for an association between HIV-positive child all-cause mortality and Fc gamma RIIa genotype. This study provides the first evidence that the infant Fc gamma RIIa His/His131 genotype is associated with susceptibility to perinatal HIV-1 transmission and further suggests that there is a dose-response relationship for the effect of the Fc gamma RIIa His131 gene on transmission.