Mechanism and intervention of murine transfusion-related acute lung injury caused by anti-CD36 antibodies.

Anti-CD36 Abs have been suggested to induce transfusion-related acute lung injury (TRALI) upon blood transfusion, particularly in Asian populations. However, little is known about the pathological mechanism of anti-CD36 Ab-mediated TRALI, and potential therapies have not yet been identified. Here, we developed a murine model of anti-CD36 Ab-mediated TRALI to address these questions. Administration of mouse mAb against CD36 (mAb GZ1) or human anti-CD36 IgG, but not GZ1 F(ab')2 fragments, induced severe TRALI in Cd36+/+ male mice. Predepletion of recipient monocytes or complement, but not neutrophils or platelets, prevented the development of murine TRALI. Moreover, plasma C5a levels after TRALI induction by anti-CD36 Abs increased more than 3-fold, implying a critical role of complement C5 activation in the mechanism of Fc-dependent anti-CD36-mediated TRALI. Administration of GZ1 F(ab')2, antioxidant (N-acetyl cysteine, NAC), or C5 blocker (mAb BB5.1) before TRALI induction completely protected mice from anti-CD36-mediated TRALI. Although no significant amelioration in TRALI was observed when mice were injected with GZ1 F(ab')2 after TRALI induction, significant improvement was achieved when mice were treated postinduction with NAC or anti-C5. Importantly, anti-C5 treatment completely rescued mice from TRALI, suggesting the potential role of existing anti-C5 drugs in the treatment of patients with TRALI caused by anti-CD36.

Improvement of Anti-CD36 Antibody Detection via Monoclonal Antibody Immobilization of Platelet Antigens Assay by Using Selected Monoclonal Antibodies.

Antibodies against human CD36 are responsible for several immune-mediated disorders. The detection of anti-CD36 antibodies using the standard monoclonal antibody (mAb) immobilization of platelet antigens (MAIPA) assay is hampered by a high frequency of false-negative results, most likely due to competitive inhibition of the mAb used as the capture antibody. We generated a panel of mouse mAbs against CD36 and seven hybridomas (GZ-3, GZ-13, GZ-70, GZ-143, GZ-413, GZ-507, and GZ-608), which were selected for MAIPA assays, as they reacted with mouse and human CD36. Fourteen anti-CD36 sera were assayed; all of which showed a positive reaction in a PakPlus (Immucor GTI Diagnostics, Inc., Waukesha, WI, USA) ELISA-based screening (optical density: 0.257-2.292). When the reference anti-CD36 mAb FA6-152 was used in the MAIPA assay, only 6/14 (42.9%) sera displayed a positive reaction. In contrast, anti-CD36 antibodies were detected in 13/14 (92.9%) sera when GZ-70 and GZ-608 mAbs were used. This significant improvement resulted in the identification of anti-CD36 antibodies by an antigen capture assay. Since patient's platelets possibly carrying rare native antigens are used, this method will facilitate the identification of new platelet antibodies against CD36 that are involved in immune-mediated thrombocytopenia and other diseases, such as transfusion-related acute lung injury.

Successful prenatal therapy for anti-CD36-mediated severe FNAIT by deglycosylated antibodies in a novel murine model.

Recent studies have shown that maternal anti-CD36 antibodies represent a frequent cause of fetal/neonatal alloimmune thrombocytopenia (FNAIT) in Asian and African populations. However, little is known about the pathomechanism and antenatal treatment of anti-CD36-mediated FNAIT. Here, we established a novel animal model to examine the clinical features of pups from immunized Cd36-/- female mice after breeding with wild-type male mice. Mild thrombocytopenia was observed, but high pup mortality was also documented (40.26%). Administration of intravenous immunoglobulin (IVIG) (1 g/kg) on days 7, 12, and 17 to immunized Cd36-/- mothers after breeding reduced fetal death (12.70%). However, delaying the IVIG administration series on days 10, 15, and 20 did not reduce fetal death (40.00%). In contrast, injection of deglycosylated anti-CD36 (deg-anti-CD36) polyclonal antibodies (5 mg/kg) on days 10, 15, and 20 significantly reduced fetal death (5.26%). Subsequently, monoclonal antibodies (mAbs) against mouse CD36 were developed, and one clone producing high-affinity anti-CD36 (termed 32-106) effectively inhibited maternal antibody binding and was therefore selected. Using the same approach of deg-anti-CD36, the administration of deg-32-106 significantly reduced fetal death (2.17%). Furthermore, immunized Cd36-/- mothers exhibited placental deficiency. Accordingly, maternal anti-CD36 antibodies inhibited angiogenesis of placenta endothelial cells, which could be restored by deg-32-106. In summary, maternal anti-CD36 antibodies caused a high frequency of fetal death in our animal model, associated with placental dysfunction. This deleterious effect could be diminished by the antenatal administration of IVIG and deg-mAb 32-106. Interestingly, treatment with deg-32-106 seems more beneficial considering the lower dose, later start of treatment, and therapy success.

[Construction of eukaryotic expression vector for human platelet CD36 gene 220C>T and 429+4insg variants and analysis of their expressions in HEK293T cells].

OBJECTIVE: To construct eukaryotic expression vectors for human platelet CD36 gene 220 C>T and 429+4insg variants and analyze their expressions in HEK293T cells. METHODS: RNA was isolated from human platelets and reversely transcribed into cDNA. Sequences of 220C>T and 429+4insg variants were derived by PCR amplification. The target sequence was ligated into a pcDNA3.1/V5-His-TOPO vector by TA cloning, which was transformed into TOP10 E. coli. Positive plasmids were screened by blue-white selection. After sequencing, plasmid DNA carrying 220C>T or 429+4insg variant was used to transfect HEK293T cells with the help of effectene. Expression of CD36 protein was then analyzed by flow cytometry and Western blotting. RESULTS: An eukaryotic expression vector pcDNA3.1/V5-His-CD36 (220C>T/429+4insg) was constructed by TA cloning. After transfected into HEK293T cells, the 220C>T and 429+4insg variants resulted in CD36 deficiency in HEK cells, which was confirmed by flow cytometry and Western blotting. CONCLUSION: The 220C>T and 429+4insg variants can cause CD36 deficiency in human platelets. This system may be used for assessing the effect of 220C>T, 429+4insg, and other variants on the expression of CD36.

Successful management of a hydropic fetus with severe anemia and thrombocytopenia caused by anti-CD36 antibody.

Cases of CD36 deficiency are not rare in Asian populations, foetal and neonatal alloimmune thrombocytopenia (FNAIT) caused by anti-CD36 isoantibodies appears more frequent than other HPA alloantibodies. However, little is known about the treatment of anti-CD36 mediated FNAIT in this region. A Chinese male foetus, whose mother had a history of multiple intrauterine foetal demise and/or hydrops, was diagnosed with severe FNAIT at 27 weeks of gestational age. Immunological analysis revealed total absence of CD36 on platelets and monocytes from mother, caused by a 329-330delAC mutation of the CD36 gene. Anti-CD36 and anti-HLA class I antibodies were detected in the maternal serum, whereas only anti-CD36 isoantibodies were detectable in the foetal blood sample. Serial intrauterine transfusions with red blood cells (RBC) and platelets from a CD36null donor were performed to improve the severe anaemia and thrombocytopenia. The baby (2250 g; Apgar scores 10) was delivered vaginally at 32 weeks of gestation with normal haemoglobin (186 g/L) but low platelet count (48 × 109/L). After 2 days the platelet count rose to 121 × 109/L. This report suggests that intrauterine transfusions with compatible RBC and CD36null platelets are useful in preventing the deleterious clinical effects of anti-CD36-mediated severe FNAIT.

Simultaneous genotyping of HPA-17w to -21w by PCR-SSP in Chinese Cantonese.

Studies have reported the polymorphism of human platelet antigen (HPA)-17w, -18w, -19w, -20w, and -21w. However, the distribution of these five antigens in Chinese Cantonese is still unknown. In this study, we designed new sequence-specific primers for HPA-19w to -21w and used published primers for HPA-17w and -18w to develop a polymerase chain reaction with the sequence-specific primers (PCR-SSP) method for simultaneously genotyping HPA-17w to -21w. A total of 820 unrelated Cantonese apheresis platelet donors in Guangzhou were involved in this study. Among the five HPAs, complete a/a homozygosity was observed for HPA-17w to -20w with an allele frequency of 1.0000. For HPA-21w, nine individuals (9/820, 1.10%) were found to be HPA-21a/bw heterozygous and the allele frequencies of HPA-21a and HPA-21bw were 0.9945 (1631/1640) and 0.0055 (9/1640), respectively. The reliability of the PCR-SSP method was determined by comparing with the genotyping results by DNA sequencing, and no inconsistencies were observed between the two methods. This study provides a reliable PCR-SSP method for simultaneously genotyping HPA-17w to -21w and could improve HPA-matched platelet transfusion in Chinese Cantonese.

[A novel human leukocyte antigen-A*33:44 allele revealed by sequence analysis].

OBJECTIVE: To analyze the sequence of a novel human leukocyte antigen (HLA)-A*33:44 allele. METHODS: A novel HLA-A allele was found by double-stranded sequencing combined with single-stranded sequencing. The frequency of the novel allele was determined by population survey. RESULTS: Genomic sequence of this novel HLA-A*33:44 allele (accession No. HQ873871) has differed from HLA-B*33:03:01 by one nucleotide in exon 4, which resulted in nt 866 G→ A substitution, which results in an amino acid substitution from Gly(GGT) to Asp(GAT) at codon 265. This alternation is a new single nucleotide polymorphism compared with other HLA-A alleles. The frequency of this new allele is less than 0.0003 in Chinese Han population. CONCLUSION: A mutation has been found in exon 4 of the novel HLA-A*33:44 allele, which may provide more information for HLA gene study.

Studies on CD36 deficiency in South China: Two cases demonstrating the clinical impact of anti-CD36 antibodies.

CD36 (also known as GPIV) deficiency is known to be responsible for the production of anti-Nak(a) antibodies in different clinical settings such as fetal/neonatal alloimmune thrombocytopenia (FNAIT), platelet transfusion refractoriness (PTR) and post-transfusion purpura (PTP). However, no data regarding the relevance of CD36 immunisation is currently available for China. In this study, healthy blood donors were typed for CD36 deficiency using flow cytometry. Nucleotide sequencing was performed to identify the molecular basis underlying the CD36 deficiency. Anti-Nak(a) antibodies in CD36-deficient individuals were analysed by ELISA and flow cytometry. By analysis of 998 healthy blood donors, 18 individuals failed to express CD36 on their platelets. In 5/12 individuals no CD36 expression was detected both on platelets and monocytes. This result suggested that the frequencies of type I CD36 deficiency (platelets and monocytes) and type II CD36 deficiency (platelets only) are approximately 0.5 and 1.3%, respectively. Nucleotide sequencing analysis of type I CD36 deficient individuals revealed eight different mutations; four of them were not described so far. However, 1228-1239del ATTGTGCCTATT and 329-330delAC appear to be the most common mutations related to type I CD36 deficiency in South Chinese population. Further analysis showed that 1/5 type I CD36 deficient individuals developed anti-Nak(a) antibodies. In addition, anti-Nak(a) antibodies could be identified in two cases of thrombocytopenia associated with FNAIT and PTR. In conclusion, more than 0.5% of CD36 type I-deficient individuals are at risk to be immunised through blood transfusion or pregnancy in China. Testing of anti-Nak(a) antibodies should be considered in FNAIT and PTR suspected cases. A registry of CD36-deficient donors should be established to allow treatment of immune-mediated bleeding disorders caused by anti-Nak(a) antibodies.

Distribution of MICA haplotypes in a Chinese Han population.

The MICA gene encodes nonclassical major histocompatibility complex class I molecules, centromeric to HLA-B and telomeric to HLA-DRB1. The MICA genes are polymorphic. The immune response against MICA may correlate with a decrease in graft survival after transplantation. However, data on the frequency of MICA polymorphisms in different populations are limited. In this study, we determined MICA allelic frequencies in a Han population living in Guangdong Province in south China. A total of 15 MICA alleles were identified using sequence-based typing. The most frequent allele was MICA*010 (22.22%), followed by MICA*002:01(18.56%), MICA*008:01(16.32%), and MICA*019(14.93%). The MICA null gene (MICA*Del) exhibited a frequency of 1.743% in this population. MICA and HLA, MICA-HLA-B, and MICA-HLA-A/HLA-B/HLA-DRB1 haplotype frequencies were estimated. The most common 2-, 3- and 4-locus haplotypes were HLA-B*40:01-MICA*008:01 (13.70%), HLA-A*11:01-B*40:01-MICA*008:01(8.25%), and HLA-A*33:03-B*58:01-DRB1*03:01-MICA*002:01(5.22%). A new MICA allele, MICA*061, was identified and appears to be evolutionarily related to MICA*012:01. This study provides high-resolution information on the distribution of haplotypes with MICA, HLA-A, HLA-B, and HLA-DRB1 in China. This information should help determine the mechanisms underlying diseases and allotransplant rejection associated with MICA polymorphisms in the southern Chinese Han population.

The frequencies of human neutrophil alloantigens in the Chinese Han population of Guangzhou.

BACKGROUND: Antibodies against polymorphic structures on human neutrophil antigens (HNAs) play a role in alloimmune-mediated neutropenia and are the leading cause of antibody-mediated transfusion-related acute lung injury (TRALI). This study aimed to determine the frequencies of HNAs in the major Han ethnic group living in Guangdong Province, Southern China. STUDY DESIGN AND METHODS: A total of 493 healthy Chinese Han blood donors from Guangzhou were recruited. DNA samples were isolated and typed for all five HNA-1, -2, -3, -4, and -5 systems using allele-specific polymerase chain reaction approaches. Results were compared with available data from other Chinese cohorts and other Asian and Caucasian populations. RESULTS: In this cohort, the gene frequency for HNA-1a (0.667) was approximately twice that of HNA-1b (0.333). In contrast to Caucasian populations, HNA-1a represents the most frequent allele in the Chinese population. HNA-3 system genotyping revealed comparable frequencies for HNA-3a (0.738) and -3b (0.262) in Chinese and Caucasian populations. Homozygous HNA-3 bb individuals were found in 5.64% of our cohort. HNA-4 genotyping revealed no HNA-4 bb homozygous individuals. In contrast, HNA-5 bb homozygous individuals represented 2.43% of the population. Typing the HNA-2 system for the single-nucleotide polymorphism C42G showed that the C-allele (69%) is overrepresented and is associated with an increased number of HNA-2a-positive neutrophil subpopulations. CONCLUSION: This study describes for the first time the frequencies of all HNA systems, including the newly identified HNA-3, within one cohort of Chinese Han population. Comparison with Caucasian populations may allow assessment of anti-HNA alloimmunization and estimation of alloimmune neutropenia and TRALI incidence in Chinese populations.

[Study of the platelet GP specific antibodies and HLA antibodies expression in platelet transfusion refractoriness patients].

OBJECTIVE: To investigate the correlation between the platelet GP specific antibodies/HLA antibodies and platelet transfusion refractoriness (PTR). METHODS: Sixty-five patients with PTR were selected in this study and were genotyped for HLA-A and HLA-B as well as HPA systems by standard PCR-SSP assays. The platelet GP specific antibodies and HLA antibodies in serum and platelet elution were tested with a solid phase ELISA. RESULTS: The HLA-A/B antigens and the frequencies of HPA-1, 2, 4, 5, 6, 9, 15 antigens in PTR patients had no difference from those in healthy donors. The freguencies of HPA-3a and 3b were 0.65 and 0.35, respectively. There was statistical difference between the 65 PTR patients and the healthy donors in HPA-3 freguencies (P < 0.05). Twenty-four patients (36.9 %) only expressed HLA antibodies, and 14 (21.5%) expressed HLA and platelet GP specific antibodies. The highest expression of anti-HLA-A/B specific antibodies was -A*9(46.2 %)/-B*40(33.6%), respectively. In serum, GPIIb/IIIa was expressed (26.2%), followed by GPIa/IIa (21.5 %). In platelet elution, GPIIb/IIIa was expressed of 41.5% and GPIb/IX 41.5%. Pedigree study was carried out for 2 patients. The results showed that the platelet GP specific antibody/HLA antibody developed in PTR patients was highly related to the mismatch with the platelet antigen/HLA antigen in their parents. CONCLUSION: The expressions of the HLA and platelet GP specific antibodies are the most important reason in PTR, it's meaningful to explore the correlation between PTR and HLA and HLA-A/B antigen in guiding platelet transfusion.

[Expression of anti-platelet glycoprotein specific antibodies and anti-HLA antibodies in idiopathic thrombocytopenic purpura].

In order to investigate the expression of the anti-platelet glycoprotein specific antibodies and anti-HLA antibodies in idiopathic thrombocytopenic purpura (ITP), 45 patients with ITP were selected in this study. An easy PCR-SSP assay was used to detect single-nucleotide polymorphisms or deletion in HPA and HLA systems. The anti-platelet glycoprotein specific antibodies and anti-HLA antibodies in plasma or platelet eluate were tested with a solid phase ELISA. The results indicated that the anti-platelet glycoprotein specific antibodies were detected in plasma or platelet eluate of 45 patients, among which anti-GPIIb/IIIa/and anti-GpIb/IX were most common. Both the anti-platelet glycoprotein specific antibodies and anti-HLA antibodies were found in plasma of 11 patients. Pedigree investigation in 2 patients (case 37 and case 40) was carried out, the results showed that anti-platelet glycoprotein specific antibodies and anti-HLA antibodies detected in 2 patients closely related to incompatibility with platelet antigens and HLA antigens in parents. In conclusion, the results suggested that detection of the anti-platelet glycoprotein specific antibodies and anti-HLA antibodies in plasma or platelet eluate in combination with investigation of clinical manifestation of patients is important for diagnosis of idiopathic thrombocytopenic purpura.

[Biological appraisal of human bone marrow mesenchymal stem cells during ex-vivo expansion].

This study was aimed to investigate the characteristics of human bone marrow mesenchymal stem cells during ex-vivo expansion, MSCs were isolated from human bone marrow. At each passage, the characteristics of proliferation kinetics, osteogenic and adipogenic differentiation potential were analyzed, and cell morphology, surface markers were investigated as well. The karyotype analysis was done in different passage cells. The infection HIV, HCV, HBV and TP were detected by ELISA. Mycoplasma contamination in vitro was detected by PCR method. HLA-SBT was used to reanalyze the results of HLA antigens and alleles. STR genetic loci were detected by PCR in the MSC1, MSC2, MSC3 and MSC4. The results indicated that the proliferative ability and osteogenic potential decreased with the increase of passage number during culture expansion. The multiple differentiation potential of MSCs was maintained during their life span. Karyotype analysis showed that MSCs from 4 groups before passage 8 were normal. The expression of CD29, CD44, CD105, CD166 and CD73 were positive. The expression of CD14, CD34, CD45, CD80, CD86 were all negative. SBT was used to identify HLA-A, B, Cw, DRB1, DRPB1, DQ alleles in the MSC1, MSC2, MSC3, MSC4. The genetype of STR in the MSC1, MSC2, MSC3, MSC4 was different. MSC 3 was examined by TP-ELISA to confirm the infectious disease of TP. MSC2 was contaminated by mycoplasma at passage 5. It is concluded that culture expansion causes MSCs to gradually lose their stem cell properties. During ex-vivo expansion of MSCs, the osteogenic differentiation potential is decreased. MSCs before passage 8 can be a valuable subject for basic research and clinical application.