Platelet Serotonin (5-HT) Concentration, Platelet Monoamine Oxidase B (MAO-B) Activity and HTR2A, HTR2C, and MAOB Gene Polymorphisms in Asthma

The complex role of the serotonin system in respiratory function and inflammatory diseases such as asthma is unclear. Our study investigated platelet serotonin (5-HT) levels and platelet monoamine oxidase B (MAO-B) activity, as well as associations with HTR2A (rs6314; rs6313), HTR2C (rs3813929; rs518147), and MAOB (rs1799836; rs6651806) gene polymorphisms in 120 healthy individuals and 120 asthma patients of different severity and phenotypes. Platelet 5-HT concentration was significantly lower, while platelet MAO-B activity was considerably higher in asthma patients; however, they did not differ between patients with different asthma severity or phenotypes. Only the healthy subjects, but not the asthma patients, carrying the MAOB rs1799836 TT genotype had significantly lower platelet MAO-B activity than the C allele carriers. No significant differences in the frequency of the genotypes, alleles, or haplotypes for any of the investigated HTR2A, HTR2C and MAOB gene polymorphisms have been observed between asthma patients and healthy subjects or between patients with various asthma phenotypes. However, the carriers of the HTR2C rs518147 CC genotype or C allele were significantly less frequent in severe asthma patients than in the G allele carriers. Further studies are necessary to elucidate the involvement of the serotonergic system in asthma pathophysiology.

Transient pseudothrombocytopenia (PTCP) in the neonate due to the mother

Thrombocytopenia with platelet count <50×10⁹/L is common laboratory finding in a severely ill newborn in neonatal intensive care units (ICU). Neonates with severe thrombocytopenia are at risk of bleeding. Most dangerous is intracerebral hemorrhage (ICH) frequently leading to death or lifelong neurological sequels. Pseudothrombocytopenia (PTCP) is a rare in vitro phenomenon of falsely low platelet count determined on hematology analyzers due to platelet clumping in ethylenediaminetetraacetic acid (EDTA) anticoagulated blood. PTCP was also reported in pregnant women with isolated thrombocytopenia. EDTA-PTCP in the neonate due to the transplacental transmission of maternal antibodies has been reported only in a few cases. Although PTCP is rare phenomenon, it should always be excluded in newborns with isolated thrombocytopenia to avoid erroneous interpretation of platelet and leukocyte count, unnecessary laboratory investigation of false positive antiplatelet antibodies and needless platelet transfusions. We report on two cases of transient PTCP in a neonate due to transplacental transfer of maternal EDTA-dependent autoantibodies of IgG class from the same mother.

RhD alloimmunization by DEL variant missed in donor testing

INTRODUCTION

Exposure to normal or variably expressed RhD antigens in an antigen-negative individual can elicit an immune response and lead to the formation of clinically significant anti-D alloantibodies. We present the case of anti-D alloimmunization by DEL variant missed in routine blood donor screening.

MATERIAL AND METHODS

Blood donors were typed for D antigen using the direct serologic micromethod. Nonreactive samples were confirmed in the indirect antiglobulin method with an IgM/IgG anti-D monoclonal reagent. Genomic DNA was extracted using a commercial QIAamp DNA Blood Mini kit on the QIAcube device (Qiaqen, Germany). RHD genotyping was performed using the PCR-SSP genotyping kits- Ready Gene D weak, Ready Gene D weak screen, Ready Gene CDE, and Ready Gene D AddOn (Inno-Train, Germany). Unidentified alleles were sent for DNA genome sequencing.

RESULTS

After identifying DEL positive blood units in RhD negative blood donor pool, a look-back study was performed to determine if their previous donations caused alloimmunization in recipients. Out of 40 D negative recipients, one developed anti-D alloantibody after 45 days. The patient did not receive other RhD positive blood products. Blood donor typed D negative in direct and indirect agglutination method. RHD screening was positive, but RHD genotyping and DNA sequencing showed no mutation indicating the normal genotype.

CONCLUSION

Currently used methods in RHD genotyping are insufficient to identify many variant alleles, especially intronic variations. We suggest additional gene investigation including yet unexplored regions of regulation and intron regions to justify our serological finding.

Plasma Brain-Derived Neurotrophic Factor (BDNF) Concentration and BDNF/TrkB Gene Polymorphisms in Croatian Adults with Asthma

Brain-derived neurotrophic factor (BDNF) and its tropomyosin-related kinase B (TrkB) receptor might contribute to normal lung functioning and immune responses; however, their role in asthma remains unclear. Plasma BDNF concentrations, as well as BDNF and NTRK2 (TrkB gene) polymorphisms, were investigated in 120 asthma patients and 120 healthy individuals using enzyme-linked immunosorbent assay and polymerase chain reaction, respectively. The genotype and allele frequencies of BDNF Val66Met (rs6265) and NTRK2 rs1439050 polymorphisms did not differ between healthy individuals and asthma patients, nor between patients grouped according to severity or different asthma phenotypes. Although plasma BDNF concentrations were higher among healthy subjects carrying the BDNF Val66Met GG genotype compared to the A allele carriers, such differences were not detected in asthma patients, suggesting the influences of other factors. Plasma BDNF concentration was not affected by NTRK2 rs1439050 polymorphism. Asthma patients had higher plasma BDNF concentrations than control subjects; however, no differences were found between patients subdivided according to asthma severity, or Type-2, allergic, and eosinophilic asthma. Higher plasma BDNF levels were observed in asthma patients with aspirin sensitivity and aspirin-exacerbated respiratory disease. These results suggest that plasma BDNF may serve as a potential peripheral biomarker for asthma, particularly asthma with aspirin sensitivity.

Warm red blood cell autoantibodies and clinical diagnoses in patients with or without autoimmune hemolysis

OBJECTIVES

Red blood cell autoantibodies (RBC autoAbs) of IgG class are found in the majority of patients with warm autoimmune hemolytic anemia (wAIHA) but sometimes also during the pretransfusion testing of patients with different diagnoses but without hemolysis. The aim of the study was to identify the main differences between these two groups of patients according to age, gender, subclass and titer of IgG RBC autoAbs and diagnosis.

MATERIAL AND METHODS

In the 9-year retrospective study, data were collected from records of 291 patients with IgG RBC autoAbs detected by gel technique, from which 111 with wAIHA.

RESULTS

More than 85% of patients in both groups were over 40 years old, with male to female ratio 1:1.9 in wAIHA vs 1:1.3 in patients without hemolysis (P=0.0916). The main characteristics of patients with wAIHA vs patients without hemolysis were: IgG only 38% vs 70%, IgG+Complement 62% vs 30%, total IgG1 79% vs 55%, IgG1+IgG3 35% vs 11%, titer of 100 for IgG1+IgG3 17% vs 3% (P<0.0001), respectively, while titer of 100 for IgG1 18% vs 9% (P=0.0241). The underlying diagnosis in wAIHA vs patients without hemolysis: hematologic disorders 41% vs 22% (P=0.0006), autoimmune disorders 12% vs 13% (P=0.8033), solid tumors 5% vs 14% (P=0.0154) and surgery procedures 6% vs 26% (P<0.0001).

CONCLUSION

We observed more wAIHA patients with high titer of IgG1 and high prevalence of IgG1+IgG3 and consider that patients without hemolysis having identical results might be interesting to find out how they are protected from damage by RBC autoAbs.

Anti-D reagents should be chosen accordingly to the prevalence of D variants in the obstetric population

BACKGROUND

Resolving ambiguous results of D antigen typing is crucial for appropriate and rational administration of anti-D immunoprophylaxis and transfusion practice in obstetric population. The aim of the study was to establish selection criteria of anti-D reagents for our population.

METHODS

A total of 12 689 samples from primiparous women in Split-Dalmatia County, Croatia, were typed for RhD antigen during the period of 5 years. Ambiguous results were submitted to additional serologic investigation and genotyping. RHD genotyping was performed by commercial genotyping kits (Ready Gene weak D ^® and Ready gene CDE, Inno-Train, Kronberg, Germany). Relative frequencies and accompanying 95% confidence intervals were used to estimate the prevalence of variants.

RESULTS

The prevalence of D variants was 0.42% (95% CI 0.31; 0.53). The most common partial D variant was D Va (RHD*05.05), with the prevalence of 0.08% (95% CI 0.03; 0.13). All weak D variants were weak D types 1, 2 and 3 (RHD*weak D type 1, RHD*weak D type 2, RHD*weak D type 3). Weak D samples were distinguishable from partial D in routine typing due to the difference in reactivity of partial D samples with clones D7B8 and RUM-1. Cell line RUM-1 gives weak or negative reactions with partial DVa category.

CONCLUSION

The most common partial D variant in our population is DVa. It is recommended to use cell lines which do not strongly agglutinate DVa variant in routine RhD typing. The appropriate choice of reagents will enable the serology methods to recognize the cases in which RHD genotyping is required.

Three-Year Experience in NAT Screening of Blood Donors for Transfusion Transmitted Viruses in Croatia

Background

Croatia implemented individual donation (ID)-NAT testing of blood donors in 2013 for three viruses HBV, HCV, and HIV-1 as a mandatory test for all blood donors. This study assessed the impact of NAT screening 3 years after its implementation.

Methods

A total of 545,463 donations were collected and screened for HBV, HCV, and HIV-1 using the Procleix Ultrio Plus Assay. All initially reactive (IR) NAT samples were retested in triplicate and, if repeatedly reactive (RR), NAT discriminatory assay (dNAT) was performed. ID-NAT positive donations were confirmed by RT-PCR on the COBAS AmpliPrep/TaqMan platform.

Results

Out of 545,463 samples tested, 108 (0.02%) were RR in NAT. There were 82 (75,9%) HBV reactive, 16 (14.8%) HCV reactive, and 10 (9.3%) HIV-1 reactive samples. 51 (47.2%) samples were ID-NAT positive only. Out of these 51 NAT yield cases, 1 window period HIV-1 and 50 occult HBV infections (OBI) were determined. There were only two potential HBV DNA transmissions from OBI donors.

Conclusion

The implementation of NAT screening for three viruses has improved blood safety in Croatia. During the 3-year period, 1 window period HIV-1 and a number of occult HBV donations were identified.

Anti-D Antibodies in Pregnant D Variant Antigen Carriers Initially Typed as RhD

BACKGROUND

To evaluate the incidence, the consequences, and the prevention strategy of anti-D alloimmunizations of D variant carriers in the obstetric population of Split-Dalmatia County, Croatia.

METHODS

RhD immunization events were evaluated retrospectively for the period between 1993 and 2012. Women were tested for RhD antigen and irregular antibodies. Those with anti-D antibody who were not serologically D- were genotyped for RHD. They were evaluated for their obstetric and transfusion history and their titer of anti-D. The neonates were evaluated for RhD status, direct antiglobulin test (DAT), hemoglobin and bilirubin levels, transfusion therapy as well as phototherapy and outcome.

RESULTS

Out of 104,884 live births 102,982 women were tested for RhD antigen. Anti-D immunization occurred in 184 women which accounts for 0.9% of individuals at risk of anti-D formation. 181 cases occurred in women serologically typed as D-. Three women were partial D carriers (DVa n = 2, DNB n = 1), initially typed RhD+, and recognized as D variant carriers after the immunization occurred. Anti-D titer varied from 1:1 to 1:16. Six children were RhD+, four had positive DAT, and two underwent phototherapy.

CONCLUSION

Anti-D immunization occurred in pregnant partial D carriers (DVa, DNB). RhD+ children had serologic markers of hemolytic disease of the fetus and newborn (HDFN), with no cases of severe HDFN.

ABO blood groups and genetic risk factors for thrombosis in Croatian population

AIM

To assess the association between ABO blood group genotypes and genetic risk factors for thrombosis (FV Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations) in the Croatian population and to determine whether genetic predisposition to thrombotic risk is higher in non-OO blood group genotypes than in OO blood group genotypes.

METHODS

The study included 154 patients with thrombosis and 200 asymptomatic blood donors as a control group. Genotyping to 5 common alleles of ABO blood groups was performed by polymerase chain reaction with sequence specific primers (PCR-SSP). FV Leiden was determined by PCR-SSP, while prothrombin and methylenetetrahydrofolate reductase were determined by PCR and restriction fragment length polymorphism (PCR-RFLP).

RESULTS

There was an association between non-OO blood group genotypes and the risk of thrombosis (odds ratio [OR] 2.08, 95% confidence interval [CI], 1.32-3.27). The strongest association with thrombotic risk was recorded for A1B/A2B blood group genotypes (OR, 2.73; 95% CI, 1.10-6.74), followed by BB/O1B/O2B (OR, 2.29; 95% CI, 1.25-4.21) and O1A1/O2A1 (OR, 1.95; 95% CI, 1.15-3.31). FV Leiden increased the risk of thrombosis 31-fold in the group of OO carriers and fourfold in the group of non-OO carriers. There was no significant difference in the risk of thrombosis between OO and non-OO blood groups associated with prothrombin mutation. Non-OO carriers positive for methylenetetrahydrofolate reductase had a 5.7 times greater risk of thrombosis than that recorded in OO carriers negative for methylenetetrahydrofolate reductase.

CONCLUSION

Study results confirmed the association of non-OO blood group genotypes with an increased risk of thrombosis in Croatia.

Frequency of HPA-15a and HPA-15b (Gov a/b) Human Platelet Alloantigens in the Croatian Population

BACKGROUND

Human platelet antigen (HPA) genotyping is important for epidemiological studies because the prevalence of particular HPA allotypes differs among various populations and plays a major role in the occurrence of HPA alloimmunization. In Caucasians, antibodies to HPA-1a are the most important causes of neonatal alloimmune thrombocytopenia (NATP). Recent studies suggest that anti-HPA 15a/15b (Gov b, Gov a) might be the most likely candidate antibodies following anti-HPA-1a in inducing NATP.

METHODS

In the present study, HPA-15 system genotype was determined by PCR-SSP method in 279 unrelated subjects from the Croatian population, yielding an HPA-15a and HPA-15b frequency of 0.53 and 0.47, respectively.

RESULTS

Retrograde testing for the presence of anti-HPA-15 antibodies by use of MAIPA in 39 frozen serum samples from serologically negative cases of clinically suspect NATP produced negative results.

CONCLUSION

The clinical role of anti-HPA-15 alloantibodies was unable to be confirmed.

Dynamics of serum hepatitis C virus load and quasispecies complexity during antiviral therapy in patients with chronic hepatitis C

BACKGROUND

Hepatitis C virus (HCV) infection is a dynamic process during which viral genetic variants continuously develop as a result of the virus adaptation to the host's immune system. The level of viremia and the complexity of the hypervariable region 1 (HVR 1) quasispecies of hepatitis C virus during antiviral therapy reflect the dynamic balance between the viral and host components in response to therapy.

OBJECTIVE

The aim of the study was to evaluate the dynamics of HCV viremia and the complexity of the HVR 1 quasispecies during the induction phase of a triple combination therapy regimen in nonresponders to earlier anti-HCV treatment.

STUDY DESIGN

Ten patients with chronic hepatitis C undergoing antiviral combination therapy with interferon-alpha, ribavirin, and amantadine were studied. The serum HCV RNA level was monitored by a quantitative RT-PCR assay up to 3 months after start of treatment. The HVR 1 quasispecies complexity was analysed by an "in house" nested RT-PCR mediated single-strand conformation polymorphism (SSCP) assay.

RESULTS

Baseline serum HCV RNA levels ranged from 1.94x10(6) to 5.53x10(6) copies/ml. In all patients, HCV subtype 1b was found. At the start of therapy, the SSCP assay revealed a high complexity pattern (at least six SSCP bands) in all patients. None of the patients responded within 4 weeks of treatment, however, the serum HCV RNA level decreased by one to two logs in eight patients. At week 4 after start of treatment, there was a decrease of SSCP bands in five patients. In four patients, SSCP bands remained unchanged and in one patient SSCP bands increased. At month 3 after start of treatment, serum HCV RNA was not detectable in one patient.

CONCLUSION

Because of the low number of patients involved in this study, prediction of therapeutical success based on the quasispecies complexity was not possible. Larger studies are urgently needed.

Mapping of mhc class I and class II regions to different linkage groups in the zebrafish, Danio rerio

The mammalian major histocompatibility complex (Mhc) consists of three closely linked regions, I, II, and III, occupying a single chromosomal segment. The class I loci in region I and the class II loci in region II are related in their structure, function, and evolution. Region III, which is intercalated between regions I and II, contains loci unrelated to the class I and II loci, and to one another. There are indications that a similar Mhc organization exists in birds and amphibians. Here, we demonstrate that in the zebrafish (Danio rerio), a representative of the teleost fishes, the class II loci are divided between two linkage groups which are distinct from the linkage group containing the class I loci. The beta2-microglobulin-encoding gene is loosely linked to one of the class II loci. The gene coding for complement factor B, which is one of the region III genes in mammals, is linked neither to the class I nor to the class II loci in the zebrafish. These results, combined with preliminary data suggesting that the class I and class II regions in another order of teleost fish are also in different linkage groups, indicate that close linkage of the two regions is not necessary either for regulation of expression or for co-evolution of the class I and class II loci. They also raise the question of whether linkage of the class I and class II loci in tetrapods is a primitive or derived character.