1/4. Neonatal alloimmune thrombocytopenia caused by human leucocyte antigen-B27 antibody.Neonatal alloimmune thrombocytopenia (NAIT) occurs when maternal alloantibodies to antigens presented on foetal platelets cause their immune destruction. Whether human leucocyte antigen (HLA) antibodies can cause NAIT is controversial. Here, a patient was described who suffered from a NAIT caused by an HLA-B27 antibody. Sera from the mother and the newborn were tested for human platelet antigen antibodies and HLA antibodies by monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay, solid phase-linked immunosorbent assay (ELISA), lymphocytotoxicity assay (LCT) and flow cytometric analysis. No antibodies against cluster designation (CD)109 and platelet glycoproteins of the father were found in patient's and mother's serum. However, HLA ELISA was used to identify HLA antibody in both sera. The antibody was specified as HLA-B27 antibody. Typing results showed that the father descended hla-b27 antigen on patient and his brother. The mother was HLA-B27 negative. It is most conceivable that the previous pregnancy of the mother induced the production of anti-HLA-B27 antibody, which crossed the placenta and subsequently caused an NAIT in the case presented.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/4. Increased severity of fetal hemolytic disease with known rhesus alloimmunization after first-trimester transcervical chorionic villus biopsy.Fetomaternal hemorrhage secondary to chorionic villus biopsy has the potential to accelerate fetal hemolytic disease in the pregnant patient previously sensitized to red cell antigens. A case of poor fetal outcome after first-trimester transcervical chorionic villus sampling in an alloimmunized patient is reported. An increase in antibody titers was associated with the demise of a hydropic fetus early in the second trimester. Maternal red cell alloimmunization is suggested as an absolute contraindication for chorionic villus sampling performed for genetic indications.- - - - - - - - - - ranking = 0.11111111111111keywords = antigen (Clic here for more details about this article) |
3/4. HPA-10w(b) (La(a)): genetic determination of a new platelet-specific alloantigen on glycoprotein IIIa and its expression in COS-7 cells.The heterodimeric complex glycoprotein (GP)IIb-IIIa, the fibrinogen receptor of platelets, carries numerous alloantigen systems. These polymorphisms are responsible for the immune response after transfusion or during pregnancy. In the latter case, the mother develops an antibody against an epitope present on fetal platelets, and this results in platelet destruction in the fetus. In this report, we describe the molecular characterization of a new alloantigen (La(a)) on GPIIIa responsible for neonatal alloimmune thrombocytopenia (NAIT). Using polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) and dna sequencing, we found a point mutation (G to A) in a heterozygous state on the GPIIIa gene leading to amino acid substitution Arg to Gln at position 62 of the mature protein. Transient expression of GPIIb-IIIa complexes in Cos-7 cells using wild-type or mutated GPIIIa cDNA allowed us to demonstrate that this mutation was responsible for expression of the La(a) epitope.- - - - - - - - - - ranking = 0.66666666666667keywords = antigen (Clic here for more details about this article) |
4/4. Neonatal alloimmune thrombocytopenia associated with maternal anti-HLA antibody: a case report.PURPOSE: Although neonatal alloimmune thrombocytopenia (NAIT) due to maternal sensitization to human platelet antigens is well described, the role of maternal anti-human lymphocyte antigen (HLA) antibodies in NAIT is not yet firmly established. PATIENT: A 31-week-old girl born prematurely to a G2POA1 mother was noted to have thrombocytopenia which lasted 18 days without any evidence of infection. MATERIALS AND methods: Platelet-associated IgG, anti-platelet antibody, and platelet PL(A1) antigen typing were determined using a commercial solid-phase red cell adherent test. antibodies to platelet glycoproteins human platelet antigen (HPA) 1 to 5 were determined using a commercial ELISA. Anti-HLA antibodies were assayed using a standard lymphocytotoxicity test. Activities and IgG subclass of anti-HLA antibodies in plasma of the mother and other postpartum mothers were measured using purified hla antigens in an enzyme linked immunoassay. RESULTS: Both mother and infant were positive for HPA-1 (PL(A1)) antigens. The mother's HLA phenotype was A3, A31, B7, B27. The level of platelet-associated IgG was not increased on maternal platelets; however, increased platelet-associated IgG was detected on the infant's platelets. antibodies to platelet glycoproteins HPA1 to 5 were not detectable in the maternal plasma. Maternal serum was positive for anti-HLA antibodies, which reacted to 23 of 27 panel cells. The presence of HLA antibodies was confirmed by enzyme-linked immunoassay. Of note, the maternal antibodies reacted positively to the infant's platelets and anti-IgG anti-HLA antibodies were detected in the serum sample from the infant collected at birth. When the activity and IgG subclass of the maternal anti-HLA antibodies were compared with those of other mothers known to have high anti-HLA antibody activity, no differences were noted. CONCLUSION: This report documents a patient with neonatal thrombocytopenia induced by maternal IgG anti-HLA antibody. Neither activity nor IgG subclass could explain the occurrence of NAIT. The factors that contribute to NAIT induced by maternal anti-HLA antibodies remain to be identified.- - - - - - - - - - ranking = 0.66666666666667keywords = antigen (Clic here for more details about this article) |