The Impact of Using Genotyped Reagent Red Blood Cells in Antibody Identification.

BACKGROUND: The detection and identification of antibodies to red blood cell (RBC) antigens is one of the most important and challenging issues in transfusion medicine. Up to date there are 354 RBC antigens recognized by the International Society of Blood Transfusion (ISBT). The reagent RBCs used in commercial antibody screening and identification panels however are usually serologically typed for up to 40 clinically important antigens. Thus the identification of many antibody specificities remains impossible when using reagent RBCs with only limited information about their antigens. To improve the pre-transfusion diagnostics, we developed antibody identification panels with reagent RBCs serologically typed for 26 antigens and additionally genotyped for 30 blood group alleles. METHODS: The reagent RBCs in the panels were characterized serologically for the clinically most significant 'standard' antigens. The reagent RBC donors were additionally genotyped by using in-house PCR-SSP methods. The antibody identification was performed in the indirect antiglobulin test using untreated and papain-treated RBCs in the gel technique. Antibodies identified due to the genotype information were confirmed by serology using appropriate reference RBCs. RESULTS: Within a time period of 3 years and 8 months, 16,878 blood samples from 8,467 patients were tested in our reference laboratory. In total, 21 different antibodies from 10 different blood group systems could be identified in 126 patients (1.5%) due to the genotype information obtained for the reagent RBCs. Antibodies to antigens from the Knops system (53 patients; 42%, 8 patients with anti-Knb) and to Cartwright antigens (31 patients; 25%) were the most frequent. CONCLUSION: The use of genotyped reagent RBCs in antibody identification panels extends the range of detectable antibody specificities, accelerates the antibody identification, and improves the pre-transfusion diagnostics.

A Novel Variant B Allele of the ABO Blood Group Gene Associated with Lack of B Antigen Expression.

SUMMARY: BACKGROUND: The gene locus for the ABO blood group system encodes a glycosyltransferase. Alterations in the DNA sequence are associated with the blood groups and the expression levels of antigens on red blood cells. A number of ABO alleles have been described as the molecular basis of weak A or B antigens. PATIENTS AND METHODS: Here, we describe a novel variant B allele in a blood donor with discrepant results in routine forward (group A) and reverse (very weak anti-B isoagglutinins) ABO blood grouping. RESULTS: Determination of the ABO genotype using polymerase chain reaction-sequence-specific primers (PCR-SSP) indicated blood group A(2)B. Sequencing of the ABO gene exons 6 and 7 showed for 1 allele a G insertion into the GGGGGG sequence at position 811-816 of exon 7. The 816insG mutation (designated ABO*Bw20) led to a frame shift of the coding sequence and subsequent alteration of the protein sequence. The location of the mutation on a B allele was proven by PCR-SSP. Screening for the novel mutation in 211 blood donors with regular ABO phenotypes indicated that *Bw20 is a rare variant. CONCLUSIONS: The low levels of anti-B isoagglutinins associated with this novel variant indicate that residual undetectable amounts of B antigen may be present on red blood cells. The serological and molecular analysis of members of the blood donor's family further proved the phenotype-genotype correlation of the *Bw20 allele with antigen O and individually variable levels of anti-B isoagglutinins. The characterization of novel alleles associated with ABO subgroups may ensure the correct determination of blood groups in which serological methods are combined with molecular genetic approaches.

Chlamydophila pneumoniae induces expression of toll-like receptor 4 and release of TNF-alpha and MIP-2 via an NF-kappaB pathway in rat type II pneumocytes.

BACKGROUND: The role of alveolar type II cells in the regulation of innate and adaptive immunity is unclear. Toll-like receptors (TLRs) have been implicated in host defense. The purpose of the present study was to investigate whether Chlamydophila pneumoniae (I) alters the expression of TLR2 and/orTLR4 in type II cells in a (II) Rho-GTPase- and (III) NF-kappaB-dependent pathway, subsequently (IV) leading to the production of (IV) pro-inflammatory TNF-alpha and MIP-2. METHODS: Isolated rat type II pneumocytes were incubated with C. pneumoniae after pre-treatment with calcium chelator BAPTA-AM, inhibitors of NF-kappaB (parthenolide, SN50) or with a specific inhibitor of the Rho-GTPase (mevastatin). TLR2 and TLR4 mRNA expressions were analyzed by PCR. Activation of TLR4, Rac1, RhoA protein and NF-kappaB was determined by Western blotting and confocal laser scan microscopy (CLSM) and TNF-alpha and MIP-2 release by ELISA. RESULTS: Type II cells constitutively expressed TLR4 and TLR2 mRNA. A prominent induction of TLR4 but not TLR2 mRNA was detected after 2 hours of incubation with C. pneumoniae. The TLR4 protein expression reached a peak at 30 min, began to decrease within 1-2 hours and peaked again at 3 hours. Incubation of cells with heat-inactivated bacteria (56 degrees C for 30 min) significantly reduced the TLR4 expression. Treated bacteria with polymyxin B (2 mug/ml) did not alter TLR4 expression. C. pneumoniae-induced NF-kappaB activity was blocked by TLR4 blocking antibodies. TLR4 mRNA and protein expression were inhibited in the presence of BAPTA-AM, SN50 or parthenolide. TNF-alpha and MIP-2 release was increased in type II cells in response to C. pneumoniae, whereas BAPTA-AM, SN50 or parthenolide decreased the C. pneumoniae-induced TNF-alpha and MIP-2 release. Mevastatin inhibited C. pneumoniae-mediated Rac1, RhoA and TLR4 expression. CONCLUSION: The TLR4 protein expression in rat type II cells is likely to be mediated by a heat-sensitive C. pneumoniae protein that induces a fast Ca2+-mediated NF-kappaB activity, necessary for maintenance of TLR4 expression and TNF-alpha and MIP-2 release through possibly Rac and Rho protein-dependent mechanism. These results indicate that type II pneumocytes play an important role in the innate pulmonary immune system and in inflammatory response mechanism of the alveolus.

Review of the quality monitoring methods used by countries using or implementing universal leukoreduction.

Several countries are implementing or have implemented universal leukoreduction (ULR). Specifications, leukocyte counting, and monitoring methods were essential elements in achieving process confidence and conformance. A review of these protocols is presented. A questionnaire was prepared, agreed, and circulated, and responses were collated. Different specifications have been adopted as well as disparate approaches to leukocyte counting and residual leukocyte monitoring. Parametric, nonparametric, and pass-rate methods of analysis were used. Despite these differences, users were satisfied that the methodologies were providing assurance of component quality.

Molecular basis of the JAHK (RH53) antigen.

BACKGROUND: The JAHK antigen was first described in 1995 as a low-frequency red blood cell antigen. Family studies confirmed the association of the antigen with the rare r(G) phenotype of the Rh blood group system, which is associated with weak expression of C and e, but normal G expression. JAHK was allocated the Rh number RH53. The serologic findings indicated the location of the antigen on the RhCE protein, although the molecular basis for JAHK has not been known. STUDY DESIGN AND METHODS: The RHCE gene of eight persons from three unrelated families was analyzed by exon amplification and direct sequencing. Four of the samples were JAHK+ the remaining four were JAHK-. In one JAHK+ sample, the entire RHCE gene was sequenced. The remaining samples were sequenced for exons 1 to 3. A polymerase chain reaction procedure with sequence specific primers was developed for the specific detection of the JAHK allele. RESULTS: Analysis of the entire RHCE gene of one JAHK+ sample showed the expected CcEe-specific nucleotide sequences and revealed an additional nucleotide change (365C>T) in exon 3. This change represented a missense mutation, which led to an amino acid substitution from serine to leucine at position 122 of the RhCE protein. Three JAHK+ samples from two other unrelated families showed the 365C>T mutation and confirmed the association of the Ser122Leu substitution with the JAHK+ phenotype. CONCLUSION: The molecular basis of the JAHK antigen (RH53) is defined by a 365C>T mutation in exon 3 of the RHCE gene leading to the amino acid substitution Ser122Leu. Because the position 122 is predicted to be located in the transmembrane region adjacent to the second loop, the substitution of the neutral serine by the hydrophobic leucine seems to be the cause of the JAHK antigen by a conformational change of the RhCE protein. This structural change may also cause the weakened expression of the C and e antigens observed in JAHK+ individuals. Based on our results it is concluded that the JAHK-specific mutation is associated with a dCe haplotype.