A mouse monoclonal antibody detecting the allospecificity HLA-A3

Recognition of HLA-A1 by murine monoclonal antibodies

Balb/c mice were immunized with cells from the mouse mastocytoma line P815 transfected with an HLA-A1 gene. The splenocytes of the immunized mice were fused with cells from the murine myeloma NS-1. In an initial screening, supernatants of growing cultures were tested for their binding capacity to the immunizing P815/A1+ cells as well as to P815/A2+ cells. Three out of 756 hybrids produced antibodies which bound to P815/A1+ cells only. They were cloned and further analyzed for their binding reactivity to reference B-lymphoblastoid cells from the Tenth International Histocompatibility Workshop. One monoclonal antibody, designated 6B11, reacted only with HLA-A1+ cells, while the two other antibodies, 3G3 and 7F10, appeared to detect antigenic determinants shared by HLA-A1, A3, A11, A26, and A30 (3G3) and by HLA-A1, A3, A11, A26, A28 and A30 (7F10). Flow cytometric studies on B-lymphoblastoid cell lines as well as on a series of tumor cell lines, including melanoma and colon carcinoma lines, confirmed the specificity of these antibodies. Monoclonal antibodies 7F10 and 6B11 were found to be of the IgM class and 3G3 of the IgG1 class. By complement-dependent 51Cr release experiments it was further shown that the two IgM antibodies 7F10 and 6B11 were able to lyse all cell lines of the HLA-A1 haplotype tested.

Two cytotoxic human-human hybridoma antibodies to HLA: TrAH10 (anti A3.1) and TrAG2 (anti B7, Bw42)

Two cytotoxic human-human hybridoma IgM antibodies to HLA were generated by EBV transformation of PBMC from multiparous women and fusion of EBV transformed cells with the human fusion partners KR4 or KR12. Both mAbs required the sensitive immunomagnetic cytotoxicity method to display killing of freshly prepared PBMC. One mAb (TrAH10) was specific for HLA-A3. Strikingly, TrAH10 reacted much more strongly with lymphoblastoid cell lines of HLA-A3.1 than of the rare variant HLA-A3.2, previously detected by cytotoxic T cells. Thus, in the microcytotoxicity test, the titer of concentrated TrAH10 was approximately 2000 times higher for A3.1 as compared to A3.2, and a clear difference was also observed in radioimmunoassay. Since the two HLA-A3 variants differ by only two amino acids at positions 152 and 156 of the alpha 2-domain's alpha-helix, the epitopes defined by the mAb TrAH10 and HLA-A3.1 specific cytotoxic T cells must be closely related. The observations with TrAH10 suggest that the HLA polymorphism detected by human mAbs may turn out to be as extensive as the T-cell defined HLA polymorphism. The other mAb (TrAG2) bound B7 and Bw42 with equal strength, and in addition bound weakly to some cells that were Bw22 or B39. Magnetic polymerbeads coated with affinity purified human mAbs TrAH10 or TrAG2 formed rosettes with EBV transformed cells carrying relevant HLA antigens; however, rosette formation with freshly isolated PBMC was very weak and unsuitable as a typing assay.

Anti-BoLA-w8 monoclonal antibody: production of a tissue typing reagent after blocking monomorphic sites on bovine mononuclear cells

A murine monoclonal antibody, WIM-8 with specificity for BoLA-w8, was generated after using an immunization protocol designed to reduce the response to bovine monomorphic determinants. BoLA-w8/w9 peripheral blood mononuclear (PBM) cells were incubated with an antiserum from mice immunized with BoLA-w10/w20 PBM cells. Splenocytes from a mouse that received three intravenous injections of the treated cells were fused with murine myelomas. A hybridoma supernatant with alloreactivity in ELISA against BoLA-w8 positive but not BoLA-w8 negative PBM cells was tested for lymphocytotoxicity in parallel with parous alloantisera. WIM-8, an IgG2b monoclonal antibody, identified the 44,000 dalton protein of the bovine MHC class I molecule present on Bos taurus and Bos indicus animals.

Generation and characterization of three new monoclonal antibodies detecting the allospecificities HLA-A2,w69, HLA-A3 and HLA-B13

Immunization of balb/c mice with peripheral blood mononuclear cells of a leukemic patient possessing the antigens HLA-A2,3; B7,35 resulted in the polymorphic monoclonal antibody (moab) UL-101/68 (IgM) defining HLA-A3. Immunization of a second group of balb/c mice with the lymphoblastoid cell line BER homozygous for HLA-A2; B13 revealed two polymorphic moabs UL-39/10 (IgG3) specific for HLA-B13 and UL-39/24 (IgG2b) defining HLA-A2,w69. Immunoprecipitation and polyacrylamide gel electrophoresis with the two moabs of the IgG isotype confirmed the class I structure of the recognized antigens.

Further antigenic determinants on HLA-A molecules

Monoclonal antibodies detect a new polymorphic antigenic determinant shared by HLA-A2, 3, 28, 29, 30, 31 and w33. This was demonstrated by population and family studies, including an HLA-A,B recombinant family, and by lysostrip experiments. Competition experiments, measuring the binding of 125I labelled MoAbs to B lymphoblastoid cell lines coated with anti-HLA conventional alloantisera and MoAbs showed that this new epitope is spatially distant from other known epitopes of A3 molecules and from monomorphic and polymorphic determinants of A2 molecules detected by monoclonal antibodies. On the other hand, anti-HLA-A2 polyclonal alloantisera are able to inhibit binding.

A cytotoxic anti-HLA-AB monoclonal antibody which in dilution becomes specific to HLA-A3 crossreacting group

XI 20.4 monoclonal antibody belongs to the IgM class. It precipitates two polypeptide chains characteristic of HLA Class I antigens. At the highest dilutions it is cytotoxic against lymphocytes carrying antigens of the HLA-A3 crossreacting group. Lysostrip experiments show that, at the lowest dilutions, the antibody reacts either with HLA-A, or B antigens.