The role of nanoparticle size in hemocompatibility.

It is expected that nanoparticular matters will be increasingly used for industrial and medical applications. Since it is known that nanoparticles exhibit unique and potential hazardous properties due to their small size, toxicity studies, risk assessment and risk management are of great interest. We focussed on adverse effects on human blood. Processes which warrant special attention are clotting, reactions triggering inflammatory and immune responses and hemolysis. Starting with the determination of size and surface charge in different media we assessed the effect of size and surface charge on induction of coagulation, thrombocyte activation, complement activation, granulocyte activation and hemolysis. We used polystyrene particles as model because they are available in different sizes but constant surface charges. The presence of salts and of protein in the dispersion solution increased particle size and neutralized surface charge. Positively charged particles formed aggregates in buffered solution. Interference of the particles with assays based on fluorescence associated cell sorting was identified. Positive surface charge induced activation of complement. Small size caused thrombocyte and granulocyte activation, and hemolysis. A characterization of particle size and surface charge in the solutions used for the experiments appears important for interpretation of the results. The size dependency of adverse effects in human blood is not linear; negatively charged particles larger than 60 nm hydrodynamic diameter appear to be considerably less hematotoxic than smaller ones.

Genetic diversity of KELnull and KELel: a nationwide Austrian survey.

BACKGROUND: Besides ABO and RH, the KEL blood group system, including the two antithetical antigens KEL1 and KEL2, is the most important owing to the frequent appearance of anti-KEL alloantibodies and their considerable clinical significance. So far, only limited information was available on KEL variant alleles determining the rare silent KELnull and KELel phenotypes with absent or diminished KEL antigen expression detected only by adsorption-elution techniques, respectively. STUDY DESIGN AND METHODS: For a systematic investigation of the KELnull and KELel phenotypes, 401 KEL:1,-2 samples (representing 2.6% of all Austrian KEL:1,-2 samples) and 811 KEL:1,2 samples were genotyped for the KEL*1/KEL*2-specific single-nucleotide polymorphism. All heterozygous KEL*1/KEL*2 and 4 additional KELnull samples were subjected to detailed immunohematologic examination and allele-specific sequencing. RESULTS: In 14 KEL:1,-2 samples, discrepant KEL*1/KEL*2 heterozygosity was observed, indicating the presence of silent or barely expressed KEL*2 alleles, whereas all KEL:1,2 individuals were homozygous for KEL*2. In the course of further molecular analysis, 8 novel KEL*2null and 2 KEL*2el alleles were discovered, representing 67 and 33 percent of previously known KEL*2null- and KEL*2el-encoding alleles, respectively. In addition, two different known KEL*2null and KEL*2el alleles each were confirmed. The immunohematologic properties of KEL variant red blood cells were defined by extended KEL phenotyping and flow cytometric KEL1, KEL2, KEL4, and KEL7 antigen as well as total Kell protein quantification. CONCLUSION: For the first time, exact KELnull and KELel population frequencies could be established in this population.

Anti-D immunization by DEL red blood cells.

BACKGROUND: No data are available on the immunogenicity of extremely weak D variants called DEL. Evaluation of alloanti-D formation in a D- female patient after transfusion of apparently D- blood from an Austrian donor led to discovery of a so far unknown DEL type. STUDY DESIGN AND METHODS: Standard blood group serologic methods were applied. Molecular typing, RHD sequencing, and D epitope mapping was performed and the absolute D antigen density determined. RESULTS: After transfusion of RBCs typed D- by routine serology, the recipient developed alloanti-D. Further evaluation with an indirect antiglobulin test confirmed donor RBCs to be D-. Molecular typing, however, demonstrated the presence of the RHD gene in one donor, and RHD sequencing revealed a deletion of four nucleotides in RHD intron 5 (RHD IVS5-38del4) as the only difference compared to the normal RHD gene. Adsorption-elution techniques demonstrated a DEL phenotype without apparent loss of D epitopes. CONCLUSION: This study documents the clinical significance of the DEL phenotype in blood units that was capable of inducing anti-D in a recipient. Qualitative data are provided on D epitope expression in DEL RBCs.

Tetragametic chimerism detected in a healthy woman with mixed-field agglutination reactions in ABO blood grouping.

BACKGROUND: The case of a healthy woman with serologic blood group AB and her biologic father showing blood group O was investigated. Further analysis, including blood, buccal swabs, and nail clippings, revealed a tetragametic chimerism. STUDY DESIGN AND METHODS: Blood grouping was performed with standard gel centrifugation test cards, ABO genotyping by sequence-specific primers (SSPs) and sequence-based typing, and HLA Class I and II typing by standard NIH cytotoxicity testing and SSP. Additionally, short-tandem-repeat (STR) and variable-number tandem-repeat (VNTR) typing was performed on blood, nail clippings, and buccal swab samples. The karyotype was analyzed by G-banded chromosomes. RESULTS: The proposita's RBCs were typed AB with a mixed-field agglutination whereas in molecular typing A, B, and O alleles were found. One paternal and two maternal haplotypes were determined by use of HLA typing. Interestingly, both paternal alleles were detected in 4 of 23 tested STR and VNTR loci only, with whole blood, nail clippings, and buccal swabs. The karyotype was identified as 46XX. The family members including the proposita's healthy twin children displayed no abnormal findings in tests performed. CONCLUSION: By investigation of DNA polymorphisms, it was possible to determine a rare case of tetragametic chimerism being the result of double parental contribution of nuclei.