Immunoglobulin V Sequences of Two Human Antiplatelet Monoclonal Autoantibodies Derived from B Cells of Normal Origin

Autoimmune thrombocytopenia has been attributed to the presence of antiplatelet autoantibodies which mediate platelet destruction. The derivation of these autoantibodies is presently unknown. While normal B cells do not produce these autoantibodies in vivo, it has been demonstrated in vitro by somatic cell hybridization that the B lymphocytes of non-thrombocytopenic individuals have the potential to produce antiplatelet autoantibodies. Antigen specificities of these antibodies are similar to those seen in autoimmune thrombocytopenic purpura and the lupus anticoagulant syndrome. The immunoglobulin V region genes encoding two such human monoclonal antiplatelet antibodies, and anti-GP IIb (STO 171) and an anti-phospholipid antibody (STO 103) derived from tonsillar lymphocytes of a non-thrombocytopenic male, have now been sequenced.These antiplatelet antibodies were found to be encoded by unmutated germline VH and VK genes. The third complementarity determining region (CDR3) of the genes encoding both of these antibodies have unique D regions with evidence of N-nucleotide additions, and the light chain genes show VK-JK junctional diversity. STO 103 is encoded by the VH4 V71-2 germline gene and a truncated JH4 gene. The light chain gene showed closest homology with the VK4 Humk18 gene and JK2 gene. STO 171 showed closest homology with the VH4.18 germline gene and had a complete germline JH6 gene. The light chain of STO 171 is encoded by the VK3 Humkv325 germline gene, which is also used by some rheumatoid factors and cold agglutinins, and a JK4 gene. Although these antibodies were not derived from circulating B cells or found to be actively producing antibody at the time they were harvested, it is possible that naturally occurring antibody producing B cells, similar to those represented here, are recruited for the development of pathogenic autoantibodies in immune thrombocytopenia. © 1994 Academic Press. All rights reserved

RhD Specific Antibodies Are Not Detectable in HLA-DRB1 Mice Challenged with Human RhD Positive Erythrocytes

The ability to study the immune response to the RhD antigen in the prevention of hemolytic disease of the fetus and newborn has been hampered by the lack of a mouse model of RhD immunization. However, the ability of transgenic mice expressing human HLA DRB1 to respond to immunization with purified RhD has allowed this question to be revisited. In this work we aimed at inducing anti-RhD antibodies by administering human RhD+ RBCs to mice transgenic for the human HLA DRB1 as well as to several standard inbred and outbred laboratory strains including C57BL/6, DBA1/J, CFW(SW), CD1(ICR), and NSA(CF-1). DRB1 mice were additionally immunized with putative extracellular immunogenic RhD peptides. DRB1 mice immunized with RhD+ erythrocytes developed an erythrocyte-reactive antibody response. Antibodies specific for RhD could not however be detected by flow cytometry. Despite this, DRB1 mice were capable of recognizing immunogenic sequences of Rh as injection with Rh peptides induced antibodies reactive with RhD sequences, consistent with the presence of B cell repertoires capable of recognizing RhD. We conclude that while HLA DRB1 transgenic mice may have the capability of responding to immunogenic sequences within RhD, an immune response to human RBC expressing RhD is not directly observed.Peer Reviewe

RhD Specific Antibodies Are Not Detectable in HLA-DRB1 * 1501 Mice Challenged with Human RhD Positive Erythrocytes

The ability to study the immune response to the RhD antigen in the prevention of hemolytic disease of the fetus and newborn has been hampered by the lack of a mouse model of RhD immunization. However, the ability of transgenic mice expressing human HLA DRB1 * 1501 to respond to immunization with purified RhD has allowed this question to be revisited. In this work we aimed at inducing anti-RhD antibodies by administering human RhD + RBCs to mice transgenic for the human HLA DRB1 * 1501 as well as to several standard inbred and outbred laboratory strains including C57BL/6, DBA1/J, CFW(SW), CD1(ICR), and NSA(CF-1). DRB1 * 1501 mice were additionally immunized with putative extracellular immunogenic RhD peptides. DRB1 * 1501 mice immunized with RhD + erythrocytes developed an erythrocyte-reactive antibody response. Antibodies specific for RhD could not however be detected by flow cytometry. Despite this, DRB1 * 1501 mice were capable of recognizing immunogenic sequences of Rh as injection with Rh peptides induced antibodies reactive with RhD sequences, consistent with the presence of B cell repertoires capable of recognizing RhD. We conclude that while HLA DRB1 * 1501 transgenic mice may have the capability of responding to immunogenic sequences within RhD, an immune response to human RBC expressing RhD is not directly observed

RhD Specific Antibodies Are Not Detectable in HLA-DRB1 1501

The ability to study the immune response to the RhD antigen in the prevention of hemolytic disease of the fetus and newborn has been hampered by the lack of a mouse model of RhD immunization. However, the ability of transgenic mice expressing human HLA DRB11501* to respond to immunization with purified RhD has allowed this question to be revisited. In this work we aimed at inducing anti-RhD antibodies by administering human RhD+ RBCs to mice transgenic for the human HLA DRB11501* as well as to several standard inbred and outbred laboratory strains including C57BL/6, DBA1/J, CFW(SW), CD1(ICR), and NSA(CF-1). DRB11501* mice were additionally immunized with putative extracellular immunogenic RhD peptides. DRB11501* mice immunized with RhD+ erythrocytes developed an erythrocyte-reactive antibody response. Antibodies specific for RhD could not however be detected by flow cytometry. Despite this, DRB11501* mice were capable of recognizing immunogenic sequences of Rh as injection with Rh peptides induced antibodies reactive with RhD sequences, consistent with the presence of B cell repertoires capable of recognizing RhD. We conclude that while HLA DRB11501* transgenic mice may have the capability of responding to immunogenic sequences within RhD, an immune response to human RBC expressing RhD is not directly observed

Immunoglobulin V region heavy and light chain gene sequences of the lymphoblastoid cell line GM 4672

GM 4672 is an IgGκ-producing lymphoblastoid cell line derived from a patient with multiple myeloma. It has been used by many laboratories as a fusion partner for the production of human-human hybridoma monoclonal antibodies. GM 4672 immunoglobulin variable region heavy and light chain family usage was originally assigned to VH1 and VK1, respectively. This assignment was based on the positions of [3H]leucine of the heavy and light chain proteins using the Edman degradation method. Using the polymerase chain reaction and variable region leader primers and constant region primers, we report here the immunoglobulin variable region gene sequence expressed by GM 4672. The VH region belongs to the VH4 family and is most homologous with the V71-2 (87.9%), Dk1, and JH4 germline genes. The entire heavy chain V region contained 41 mutations in 36 codons and included 11 N nucleotide additions flanking the D region. GM 4672 VK region contained a VK1 gene rearranged with a JK4 gene. The VK germline gene used by GM 4672 light chain was not identified but showed the most homology with Vb\u27 germline gene (87.7%). When compared to Vb\u27 and JK4 genes, there were 37 mutations in 30 codons with evidence of antigen selection as determined by the replacement to silent mutation ratio in the complementarity-determining regions. The high frequency of mutations in the V region genes of GM 4672 is comparable to the sequences of other myeloma proteins. © 1993 Butterworth–Heinemann