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

Human monoclonal antibody with T-cell-like specificity recognizes MHC class I self-peptide presented by HLA-DR1 on activated cells

Alloreactive T cells recognize peptides presented in the binding groove of major histocompatibility complex molecules (MHCs), whereas B cells mainly recognize the MHCs independent of bound peptides. Here, we demonstrate that the human B-cell repertoire comprises B cells which can be stimulated during pregnancy to produce antibodies reacting with MHCs in a way similar to T cells. The human monoclonal antibody UL-5A1 recognizes DR1(DRA/DRB1*0101) molecules on lymphoblastoid cell lines only if they co-express HLA-A2 or if they have been loaded with HLA-A2-derived peptides. The effect of the HLA-A2 peptide 105-117 on UL-5A1 reactivity was specific, time and dose-dependent. Reactivity increased when naturally processed peptides were removed from DR1 molecules before the HLA-A2 peptide 105-117 was loaded. UL-5A1 reacted specifically with cells that had been activated. The results imply a role of activation of cells in peptide processing and/or loading.

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.

Generation of a human hybridoma producing a pure anti-HLA-A2 monoclonal antibody

We report the production and characterization of a human monoclonal IgM hybridoma antibody recognizing antigen HLA-A2. B lymphocytes obtained from the peripheral blood of a multiparous volunteer 1 week postpartum were transformed in vitro by Epstein-Barr virus, screened by a microlymphocytotoxicity assay, and electrofused with the heterohybridoma fusion partner, K6H6/B5. A specifically anti-A2 secreting hybridoma cell line. MBW1, was then identified and cloned. The cytotoxic IgM antibody produced showed complete correlation (r = 1.00) with the A2 antigen on a large panel of unrelated donors' lymphocytes, and no cross-reactivity with A28, Aw68, or Aw69 antigens was observed.

Monoclonal antibody to a supertypic determinant associated with HLA-DRw52

A cytotoxic mouse monoclonal antibody UL-52 (IgG2b) was obtained after immunization of a BALB/c mouse with the lymphoblastoid cell line STA homozygous for HLA-A3, B8, Cw7, DR3, DRw52, DQw2, DPw2. Fluorescence analysis on a panel of B lymphoblastoid cell lines from the 10th International Histocompatibility Workshop 1987 showed almost exact concordance of UL-52 reactivity with the presence of the HLA-DRw52 antigen. Cytotoxicity testing of UL-52 on mononuclear cells of HLA-typed individuals revealed a pattern of reactivity closely associated with the HLA-DRw52 specificity as defined by conventional alloantisera (R = 0.77). UL-52 precipitated appropriate 29,000- and 33,000-dalton bands on SDS- polyacrylamide gels under reducing conditions from an HLA-DRw52 positive B lymphoblastoid cell line. Thus, by serological and biochemical criteria UL-52 defines a supertypic determinant associated with HLA-DRw52. In contrast to most DRw52- like monoclonal antibodies, UL-52 binds to DRw8 positive cells.